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Electronics => Projects, Designs, and Technical Stuff => Topic started by: uski on November 24, 2015, 09:44:48 pm

Title: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uski on November 24, 2015, 09:44:48 pm
Hi there !

I wanted to share the latest addition to my lab, a GPSDO :)

First I acquired a surplus used Symmetricom GPSDO PCB off eBay.
(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=183589;image)
Had to buy the corresponding pigtails separately.
The board had a oily and smelly (organic solvent ?) liquid on it so I had to wash it with IPA and let it dry... the wonders of Chinese surplus parts...

Then I made a little case using a Hammond box :
(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=183585;image)

I mounted the PCB with adhesive stand-offs :
(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=183591;image)
The PCB sits at the top of the box because I put the adhesive feets on the removable panel - not sure if it's wise as I don't know if the adhesive will be strong enough. If I have issues I'll revert the labels and everything.

There is a 1 PPS and a 10 MHz output, GPS antenna input, and a 5V 3A power supply input, all on the back :
(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=183587;image)

I moved the status LEDs which were on the PCB to the front panel ; there are two switches that I didn't move as their purpose is not fully understood and they don't seem to be needed for operation.
(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=183593;image)
(I think I know what the RST switch does... but if anyone knows what the MACT switch does, let me know !)

These units seem very similar to various other GPSDOs I've seen used in the time-nuts community.

The GPS receiver is a Furuno GT-8031 module (http://www.furuno.com/en/products/gnss-module/GT-8031) and a +5VDC bias is provided at the antenna port.
It is a 16-channel GPS timing module that supports T-RAIM and SBAS, not the latest generation but not as old as the modules used in many other GPSDOs.
This particular GPSDO unit has been first powered on in 2009 or 2011 (can't remember - logs have since been cleared) so it's pretty recent.

There is a console port (RS232 levels, and it's possible to tap into 3.3V signals before the level shifter chip, some cousin of MAX3232) which I connected to a DB9 port for diagnosis, I didn't make a hole for it yet since I'm not sure I'll keep it a DB9 or I'll put an integrated RS232-to-USB converter or even a small LCD with an arduino or similar, showing basic status information. But the LEDs are mostly enough.

So while I decide what to do with the console, I made a little adapter that I can use for initial setup and testing :
(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=183595;image)

The features are decent, for instance the unit will generate an alarm (and light up the corresponding LED) if the GPS antenna is disconnected so I guess it does a bit of self-monitoring.
If it goes into holdover for too long (for instance, something is jamming the GPS signals but the antenna is still there), then it will generate an alarm too. I think the time it waits before setting an alarm can be changed.

Settings are 57600 8N1 no flow control and the commands look like SCPI.
 
Sending a question mark ? then pressing ENTER gives a list of the supported commands :
Code: [Select]
UCCM-P > ?
*IDN?
ALARm:HARDware?
ALARm:OPERation?
DIAGnostic:OUTPut ON|OFF
OUTPut:ACTive:ENABle
OUTPut:ACTive:DISable
OUTPut:ACTive:HOLDover:DURation:THReshold <seconds>
OUTPut:ACTive:HOLDover:DURation:THReshold?
OUTPut:INACTive
OUTPut:INACTive?
OUTPut:STATe?
SYNChronization:HOLDover:DURation:STATus:THReshold <seconds>
SYSTem:PRESet
SYNChronization:TFOMerit?
LED:GPSLock?
SYNChronization:FFOMerit?
GPS:POSition N or S,<deg>,<min>,<sec>,E or W,<deg>,<min>,<sec>,<height>
GPS:POSition?
GPS:POSition:HOLD:LAST?
GPS:REFerence:ADELay <numeric value>
GPS:REFerence:ADELay?
GPS:SATellite:TRACking:COUNt?
GPS:SATellite:TRACking?
DIAGnostic:ROSCillator:EFControl:RELative?
SYNChronization:TINTerval?
DIAGnostic:LOG:READ:ALL?
DIAGnostic:LOG:CLEar
SYSTem:PON
OUTPut:MODE?
SYSTem:STATus?
SYSTem:COMMunication:SERial1:BAUD 9600|19200|38400|57600
SYSTem:COMMunication:SERial1:BAUD?
SYSTem:COMMunication:SERial1:PRESet
SYSTem:COMMunication:SERial2:BAUD 9600|19200|38400|57600
SYSTem:COMMunication:SERial2:BAUD?
SYSTem:COMMunication:SERial2:PRESet
OUTPut:STANby:THReshold <seconds>
changeSN
SYNChronization:REFerence:ENABLE LINK|GPS
SYNChronization:REFerence:DISABLE LINK|GPS
SYNChronization:REFerence:ENABLE?
STATus
POSSTATus
TOD EN|DI
TIME:STRing?
REFerence:TYPE GPS|LINK
REFerence:TYPE?
PULLINRANGE 0|1|2|...|254|255
PULLINRNAGE?
DIAGnostic:LOOP?
DIAGnostic:ROSCillator:EFControl:DATA GPS|<value>
DIAGnostic:ROSCillator:EFControl:DATA?
OUTPut:TP:SELection PP1S|PP2S
OUTPut:TP:SELection?
GPSystem:SATellite:TRACking:EMANgle <degrees>
GPSystem:SATellite:TRACking:EMANgle?
DIAGnostic:TCODe:STATus:AMASk
DIAGnostic:TCODe:STATus:OMASk
DIAGnostic:TCODe:ERRor:AMASk
DIAGnostic:TCODe:ERRor:OMASk
DIAGnostic:HOLDover:DELay
DIAGnostic:HOLDover:DELay?
GPS:SATellite:TRACking:IGNore <PRN>, ...,<PRN>
GPS:SATellite:TRACking:IGNore?
GPS:SATellite:TRACking:INCLude <PRN>, ...,<PRN>
GPS:SATellite:TRACking:INCLude?
GPS:SATellite:TRACking:<select>:ALL
Command Complete
UCCM-P >

The prompt is UCCM-P>

The identification is (I blanked the last 4 digits of the serial) :
Code: [Select]
UCCM-P > *IDN?
Symmetricom,090-03861-03,W56094xxxx,1.0.0.2-01
Command Complete

I believe these were used in GSM/UMTS/CDMA base stations. There was a log in my unit, latest GPS fix was located at the top of a high building in Japan.

At bootup it goes through several states :
OCXO WARMUP
OCXO WARM
ACTIVE

The ACT LED corresponds to the PLL lock :
Green solid : PLL unlocked
Green flashing slowly : PLL locking ("adjusting freq" then "syncing")
Green flashing fast : PLL locked to GPS
While the PLL locks I can see the frequency change slightly on the output.

In parallel, at power on, the receiver starts doing an initial GPS survey by averaging the GPS positions, takes 2 hours to finish and needs good GPS signal quality.
If GPS signal quality gets too low (low elevation or not enough sats in view), the survey will be paused and will resume later.

Boot prompt is :
Code: [Select]
Symmetricom Boot Code ver. 1.01.01


Press Enter to go to boot
Image1: [1.0.0.2] [454535 bytes] [valid checksum:0x20AFA24] [timestamp:3]
Image2: [1.0.0.1] [454535 bytes] [valid checksum:0x2142B89] [timestamp:2]

Loading Image1
UCCM-P >

There are a few status commands :

Code: [Select]
UCCM-P > SYST:STAT?
-------------------------------------------------------------------------------
090-03861-03   serial number W56094xxxx   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]                         
                                              TFOM     2             FFOM     0
                                              UCCM-P Status[ACTIVE]
                                             
>> GPS: [phase:  2.77e-08]                   
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 10 ____   Not Tracking: 1 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      19:08:57     24 NOV 2015
  5  22  87   36    10  Not OK                GPS      Synchronized to UTC
 13  53  56   37                              ANT DLY  +0.000E+00
 15  83 160   42                              Position ________________________
 18  36 282   38                              MODE     Hold
 20  73  60   40                             
 21  56 295   39                              LAT      N  45:29:xx.xxx
 24  16 162   34                              LON      W  73:33:xx.xxx
 27   5 331   32                              HGT               +84.80 m  (MSL)
 29  20 212   35                             
 30  10  34   33                             
                                             
                                             
ELEV MASK  5 deg                             
-------------------------------------------------------------------------------

Command Complete

And that one too :

Code: [Select]
UCCM-P > STATus

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [Master]
1-2. #Before ACTIVE STATUS ------------- [Master Holdover]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [NORMAL 2 MODE]
Command Complete

It's interesting, it says "UCCM slot" so UCCM is probably the product name, and it was used in slots, which apparently could be linked together for redundancy, probably through the ribbon cable connector which can be seen on the PCB picture above.

There is also a GPS-specific status command :

Code: [Select]
UCCM-P > POSSTATus
-----------------------------------------------------------------------------
11/24/2015 19:11:26
-----------------------------------------------------------------------------
 Position : LAT(N 45:29:xx.xxx) LON(W 73:33:xx.xxx) H(84.80 m MSL)
-----------------------------------------------------------------------------
 Geometry : PDOP(0.0) HDOP(0.0) VDOP(0.0)
-----------------------------------------------------------------------------
 Channel Status
   num of visible sats > 11
   num of sats tracked > 10
   ------ Receiver Channel State ------
     CH 0 >  SateID(5) TrackMode(pos avail) SigValue(39)
     CH 1 >  SateID(13) TrackMode(pos avail) SigValue(40)
     CH 2 >  SateID(15) TrackMode(pos avail) SigValue(44)
     CH 3 >  SateID(18) TrackMode(pos avail) SigValue(41)
     CH 4 >  SateID(20) TrackMode(pos avail) SigValue(41)
     CH 5 >  SateID(21) TrackMode(pos avail) SigValue(40)
     CH 6 >  SateID(24) TrackMode(pos avail) SigValue(35)
     CH 7 >  SateID(27) TrackMode(pos avail) SigValue(36)
     CH 8 >  SateID(29) TrackMode(pos avail) SigValue(36)
     CH 9 >  SateID(30) TrackMode(pos avail) SigValue(33)
     CH 10 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 11 >  SateID(0) TrackMode(code search) SigValue(0)
-----------------------------------------------------------------------------
  Rcvr Status(2) :
-----------------------------------------------------------------------------
  Antenna Voltage: 4794 mV,  Antenna Current: 10 mA
-----------------------------------------------------------------------------
Command Complete

And the best one, the timing loop status :

Code: [Select]
UCCM-P > DIAGnostic:LOOP?
-------------------------------------------------------------------------------
11/24/2015 19:12:19
-------------------------------------------------------------------------------

   LOS      MEAS       NCO STATUS WEIGHT PBUC FBUC DBUC LBUC IBUC G  M TC
-------------------------------------------------------------------------------
 0:  1  0.000e+00  0.000e+00 0x07AC   0   700  700    0    0    2  2  4 29
 1:  1  0.000e+00  0.000e+00 0x068C   0   700  700    0    0    0  2 14 226
GPS: 0 -3.037e-08 -7.041e-09 0x0000   1  ---- 1000 1000 ---- ----  3  6 31
-------------------------------------------------------------------------------
freq cor  = -7.041106e-09
phase cor = -2.000000e-11
gps phase = 2.033333e-08
temp cor  = -3.383123e-11
Command Complete

If anybody can help me make sense of that data, please feel free to do so ! I understand 0 and 1 are probably inputs to daisy chain the units so I'm not very interested in these, but what's MEAS (measured phase noise ??), NCO (??), and the TFOM and FFOM saw in the first status command above ? Any other information ? Anyone knows what kind of precision I can expect from that kind of GPSDO ? I don't care about alignment of the frequency output and PPS output to the UTC second but I care about frequency drifts (which should be 0 long term, but what about short term ?).

It's definitely a very good and useful lab instrument, I used it to calibrate a HP 5334A counter. Build one too ! :)
Title: Re: A look at my Symmetricom GPSDO (OCXO + Furuno receiver)
Post by: TheSteve on November 24, 2015, 09:55:33 pm
Excellent post - your box is very similar to mine but I used the Trimble equivalent model. Mine is also mounted inside a Hammond box.
I used the proper connector pigtails with mine but for someone looking to save even more money you could solder the coax direct to the bottom of the Trimble board and then direct to chassis mount BNC etc connectors.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Brainbox on November 29, 2015, 08:31:53 am
First, my name is Ko and I am new in this group.
I bought one of those Trimble boards from EBay and was looking for some information about this device.
A first inspection of the board learned me that one capacitor came lose frome the board and was only connected by one leg.
The seller made his excuses and I became a partial refund for this.
Because of the complete lack of info from the seller I had to find out everything by myself.
Thanks to Your postings I got it to work  and now building a nice enclosure around it.
There it was that someting strange showed up.
Without the case it works fine, but build into the metal housing the ouput changed dramatically.
Taking it out of  the enclosure output changed to normal again.
I found that the metal pads around the four mounting holes are not all connected to ground, but only two of them.
Now I mounted the two other pads with nylon screws to isolate them and that seems to solve the problem.

To @Uski; I found that the MACT switch forces it to generate an output, even with no antenna attched.
So it seems to mean Manual_Activate and shows a alternating red and green activity LED by doing this.


Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Theboel on December 01, 2015, 11:01:04 pm
Hello,
do you have manual for your symetricom UCCM board ?
the price is very appealing but I like to know if it posible to extract NMEA data from this board.
Thank You
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on December 01, 2015, 11:44:58 pm
Thanks for the post, I'm contemplating buying one of these modules. What is the main connector pinout?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on December 02, 2015, 05:06:42 am
I have not found or seen any official documentation for this board or the Trimble equivalents.(you can google for Trimble 63090 or 73090)
You can enable a once per second string but it is hex data string, not NMEA data.

As Brainbox mentioned the 4 mounting holes are not all ground - one of them is connected to the 5 volt regulator.

The M-act button does manually enable the 10 MHz output even if no GPS lock has been achieved. In the case of the my Trimble which has been running for months constantly it is very accurate in the short term from a cold start. With no GPS connected after the oven is warm it is currently within 4 mHz of proper 10 MHz. So if you had to take the unit out of the lab and just needed a quick reference it would do quite nicely even without GPS lock.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uski on December 03, 2015, 06:07:48 am
Hi everybody !

Sorry for the lack of replies from me, I didn't see I wasn't subscribed to the thread !

First, my name is Ko and I am new in this group.
I bought one of those Trimble boards from EBay and was looking for some information about this device.
A first inspection of the board learned me that one capacitor came lose frome the board and was only connected by one leg.
The seller made his excuses and I became a partial refund for this.

I had a similar problem. Those boards are probably scrap yard pulls and have probably seen pretty bad days.
It's a very good thing to inspect them before powering them up and to watch out for magic smoke at first power up (damage can often be limited if power is turned off quickly in case of apparent issue).

Because of the complete lack of info from the seller I had to find out everything by myself.
Thanks to Your postings I got it to work  and now building a nice enclosure around it.

Glad it helped, let me know if you have more specific questions :)

There it was that someting strange showed up.
Without the case it works fine, but build into the metal housing the ouput changed dramatically.
Taking it out of  the enclosure output changed to normal again.
I found that the metal pads around the four mounting holes are not all connected to ground, but only two of them.
Now I mounted the two other pads with nylon screws to isolate them and that seems to solve the problem.

I used adhesive nylon standoffs everywhere so I didn't know that. Thank for the info, it should help others :)

To @Uski; I found that the MACT switch forces it to generate an output, even with no antenna attched.
So it seems to mean Manual_Activate and shows a alternating red and green activity LED by doing this.

Great, thanks !

Hello,
do you have manual for your symetricom UCCM board ?
the price is very appealing but I like to know if it posible to extract NMEA data from this board.
Thank You

The official documentation of the Furuno receiver used shows that it uses a "NMEA like" protocol. That's probably standard NMEA with additional proprietary messages.

What application do you have in mind ? If you want to use it as a GPS receiver, I'd say, just get a dedicated GPS receiver. Unless you need a low jitter PPS output, you can get a cheap GPS receiver on eBay. If you want a more precise PPS output, then yes, you need a timing GPS receiver like this one. There is the good uBlox LEA-6T for this, or even the newer (multi-GNSS) LEA-8T.

Thanks for the post, I'm contemplating buying one of these modules. What is the main connector pinout?

I have absolutely no idea :D I didn't connect anything to it. I connected the +5V input to the fuse directly and to ground, I guessed their location from looking at the power supply layout.

The colorful ribbon you see if for the LEDs, I soldered the wires on the back of the PCB to each LED. The ribbon is not connected to the main flex connector which has tens of pins.

The power supply is also connected to the main ribbon connector.

There are definitely more possible options when using the main connector, specifically linking several of these boards together to get redundancy, but you'd have to find the pinout.

If you want to try to contact Symmetricom to get the info, feel free to do it and share the result ! :)

The M-act button does manually enable the 10 MHz output even if no GPS lock has been achieved. In the case of the my Trimble which has been running for months constantly it is very accurate in the short term from a cold start. With no GPS connected after the oven is warm it is currently within 4 mHz of proper 10 MHz. So if you had to take the unit out of the lab and just needed a quick reference it would do quite nicely even without GPS lock.

That's a pretty good info. I guess it stores OCXO calibration data in some kind of NVM to make it ready for a cold start.
I used my GPSDO today to calibrate other equipment. It's really a useful piece of hardware.

I like your case - you're right it looks pretty similar to mine ! :)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on December 03, 2015, 06:16:25 am
Ran my Trimble for 24 hours without GPS - it did very well and was still 4 mHz or less from my other GPS reference. In fact when I connected the GPS antenna a much larger error was introduced for quite a while as it re-synchronized. If anything the OCXO is over-controlled by software and made less stable in the short term. This isn't generally an issue as I leave it running 24/7. I've wanted to order the Symmetricom version to compare them for quite some time but haven't found an extra 50 dollars to throw at it as I already have two GPSDO's. When I bought my Trimble they were under 50 dollars shipped on ebay - for now the Symmetricom at under 50 is the best buy.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Deathwish on December 03, 2015, 06:32:35 am
I'm still waiting for my symetricon to arrive, I think it lost its GPS bearings between China and the UK
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Deathwish on December 03, 2015, 07:32:07 am
http://www.ko4bb.com/manuals/81.156.83.21/Furuno_GT8031_Protocol_Specification_Rev1.pdf (http://www.ko4bb.com/manuals/81.156.83.21/Furuno_GT8031_Protocol_Specification_Rev1.pdf)

http://www.ko4bb.com/manuals/81.156.83.21/Furuno_GT8031_Hardware_Specification_2005.04.28.pdf (http://www.ko4bb.com/manuals/81.156.83.21/Furuno_GT8031_Hardware_Specification_2005.04.28.pdf)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 03, 2015, 08:36:55 pm
Hi,

    I'm also building a GPSDO using this Symmetricom card.
Today I probed the Furuno pins to get the NMEA frames (Pin#2, next to the square pad one). So that's great.
But, since I want to use a GPS display module developed by another Ham (F4CTZ: http://www.f4ctz.fr/?page_id=692 (http://www.f4ctz.fr/?page_id=692)), but the little problem with this is that NMEA frames doesn't have checksum field.
I've currently modified the source code of the GPS display module to handle that kind of frames, but I have to wait for a friend to reflash the PIC.

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on December 10, 2015, 09:20:52 pm
Just to let us Symmetricon fanboys know, the MACT button does indeed enable the 10MHz output without a GPS signal. This is also possible using the serial command

DIAGnostic:OUTPut ON|OFF
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on December 11, 2015, 08:04:04 pm
Received mine yesterday, same seller I guess because it also included the oil  ;)
http://www.ebay.com/itm/121761130751 (http://www.ebay.com/itm/121761130751)

Also ordered this antenna from the same seller, it works ok:
http://www.ebay.com/itm/111734469938 (http://www.ebay.com/itm/111734469938)

And a handful of pigtails from here:
http://www.ebay.com/itm/281313869844 (http://www.ebay.com/itm/281313869844)

Looks like it lived on this building from October 2011 to at least (last log entry) April 2014:
https://www.google.com/maps/@35.361216,139.6222302,42m/data= (https://www.google.com/maps/@35.361216,139.6222302,42m/data=)!3m1!1e3

I wonder if the seller did test these, there's no evidence in the log that it was ever powered on between the building and my house.
Code: [Select]
L485:1980-01-06 00:00:02:Power On
L486:1980-01-06 00:00:36:Survey mode started
L487:1980-01-06 00:01:48:Time set to GPS
L488:2014-04-24 01:45:50:Time set to GPS
L489:2014-04-24 01:49:04:GPS lock started
L490:2014-04-24 03:44:48:Position hold mode started
L491:2014-04-24 03:44:48:Lat: N,+35,+21,+40.5
L492:2014-04-24 03:44:48:Long: E,+139,+37,+20.4
L493:2014-04-24 03:44:48:Height: +67.5
L494:1980-01-06 00:00:02:Power On
L496:1980-01-06 00:00:36:Survey mode started
L497:1980-01-06 00:07:54:Time set to GPS
L498:2015-12-11 19:10:14:Time set to GPS
L499:2015-12-11 19:11:11:GPS lock started

Initial current at 5V was 1.8A, dropping to 0.8A after the OCXO warms up.
Now to find a nice spot for the antenna and put it in a box...

Edit: The forum doesn't like links with a ! in it, so if you want to see the building copy the full link to your browser or click 'earth'.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Deathwish on December 12, 2015, 09:09:22 am
Mine is well overdue from him, ordered the same antenna from another seller, so glad to hear it works ok.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 12, 2015, 11:02:39 pm
Hi I have just ordered the symetricon and the trimble gpsdo from the same seller,i hope they work ok,
I am going to lock my kenwood ts-2000 and my 4 meter transverter and test gear with then,
how long do these take to settle at 10.000000MHZ,and what is the max voltage it can be run from?
what is the sensitivity like from the gps rx,and what number of sats do you need to be receiving for good 10mhz stability, 
what size is the unit so I can start looking for a box to fit it in,
Thanks Dave 2E0DMB 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on December 12, 2015, 11:40:48 pm
The Symmetricom and the Trimble versions of these should run at >5V-5.5V with a 2A supply no problem, PSU lead losses accounted for. Don't go too much over 5V as the supply is directly sent (minus a diode drop) to the external antenna, which are usually 3-5V.

The Symmetricom has a 12V OCXO and uses a TI PTN4050C boost converter while I understand the Trimble uses a 5V OCXO so doesn't need this.

My Symmetricom boost converter was DOA, as was the missing MCX antenna socket and the broken MACT switch.

The seller gave me the runaround and eventually pretended to send me a replacement board out and try and get me to "wait for it" one week after the ebay dispute timeout period. Of course with my simple notification that I would involve ebay he refunded me at the 11th hour.

I'm now using a cheap XL6009 instead. There are some other issues with starting this Symmetricom board with less than 1.7A too...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 13, 2015, 11:14:41 am
Hi thanks for the info,i will post when I receive them,
Thanks Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 13, 2015, 03:07:09 pm

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)

« Reply #10 on: December 04, 2015, 07:36:55 AM »


Quote

 

Hi,

    I'm also building a GPSDO using this Symmetricom card.
Today I probed the Furuno pins to get the NMEA frames (Pin#2, next to the square pad one). So that's great.
But, since I want to use a GPS display module developed by another Ham (F4CTZ: http://www.f4ctz.fr/?page_id=692 (http://www.f4ctz.fr/?page_id=692)), but the little problem with this is that NMEA frames doesn't have checksum field.
I've currently modified the source code of the GPS display module to handle that kind of frames, but I have to wait for a friend to reflash the PIC.

Cheers.
---
Daniel

Hi Daniel
Could you please The modified Hex code/File as I would like to build this display,
you say the output is on pin 2 is that in rs232 or TTL level?
Thanks Dave 2E0DMB


Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 13, 2015, 03:23:52 pm
Hi Daniel
Could you please The modified Hex code/File as I would like to build this display,
you say the output is on pin 2 is that in rs232 or TTL level?
Thanks Dave 2E0DMB

Yeah, sure.

The level is TTL.

On the display module, you have to change two components:
T1 from 2N2222 to MMBT2907 (or equivalent), and the base resistor R3, from 10k to 4k7.

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: KD0CAC John on December 13, 2015, 04:23:21 pm
Those links are not connecting for me ?







http://www.ko4bb.com/manuals/81.156.83.21/Furuno_GT8031_Protocol_Specification_Rev1.pdf (http://www.ko4bb.com/manuals/81.156.83.21/Furuno_GT8031_Protocol_Specification_Rev1.pdf)

http://www.ko4bb.com/manuals/81.156.83.21/Furuno_GT8031_Hardware_Specification_2005.04.28.pdf (http://www.ko4bb.com/manuals/81.156.83.21/Furuno_GT8031_Hardware_Specification_2005.04.28.pdf)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 13, 2015, 04:25:25 pm
Hi,

http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=02_GPS_Timing/Furuno (http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=02_GPS_Timing/Furuno) works

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 13, 2015, 04:35:24 pm
Hi Daniel
Thanks for that,I will Wait until I have the unit,
have you made your display?
would I be able to use a different display as I would like to make it on vero board,
This is one of the things I am going to use the 10mhz ref for,  http://www.vk3hz.net/XRef/XRef_Home.html (http://www.vk3hz.net/XRef/XRef_Home.html)
I have the one for the kenwood ts-2000 and I had him make me a 10mhz to 42mhz unit with a tcxo for when the 10mhz ref is not plugged in for my 4 meter transverter, the units took about 1 week to arrive in the uk
Thanks Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 13, 2015, 04:38:48 pm
Hi Dave,

 No, I didn't etched the PCB, with 2 Ham friends we ordered the last 3 kits from F4CTZ some time ago.
Maybe you could ask him if he have some new kits available.

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on December 13, 2015, 05:54:24 pm
...and the TFOM and FFOM saw in the first status command above ? Any other information ?
I just found this one.

TFOM (Time Figure of Merit) is the accuracy of the 1 PPS signal, with 0 < 1ns, 1= 1 to 10 ns, 2 = 10 to 100 ns, 3 = 100ns to 1us, ... 9 > 1ms
FFOM (Frequency Figure of Merit) is the stability of the 10MHz signal. 0 = PLL stable, 1 = stabilizing, 2 = holdover, 3 = unlocked (do not use as 10MHz out of spec)

You can use the commands SYNC:TFOM? and SYNC:FFOM? to get a description of the current state.
e.g.
Code: [Select]
UCCM-P > sync:tfom?
10-100 ns
Command Complete
UCCM-P > sync:ffom?
PLL stabilized
Command Complete

I'm trying to find other stuff and can't find the manual for this particular unit, but other symmetricom and HP GPSDO manuals seem to have similar information in them.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 13, 2015, 07:25:55 pm
Hi I did email F4CTZ: http://www.f4ctz.fr/?page_id=692 (http://www.f4ctz.fr/?page_id=692)),
about the nmea v2 gps display kit, and I got a reply from him saying that if 10 or more people want to buy the display  kit he will produce the kit again,i have asked for the price of the kit
I will post when I get the info
Thanks Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uski on December 13, 2015, 08:17:35 pm
Hi,

...and the TFOM and FFOM saw in the first status command above ? Any other information ?
I just found this one.

TFOM (Time Figure of Merit) is the accuracy of the 1 PPS signal, with 0 < 1ns, 1= 1 to 10 ns, 2 = 10 to 100 ns, 3 = 100ns to 1us, ... 9 > 1ms
FFOM (Frequency Figure of Merit) is the stability of the 10MHz signal. 0 = PLL stable, 1 = stabilizing, 2 = holdover, 3 = unlocked (do not use as 10MHz out of spec)

You can use the commands SYNC:TFOM? and SYNC:FFOM? to get a description of the current state.
e.g.
Code: [Select]
UCCM-P > sync:tfom?
10-100 ns
Command Complete
UCCM-P > sync:ffom?
PLL stabilized
Command Complete

I'm trying to find other stuff and can't find the manual for this particular unit, but other symmetricom and HP GPSDO manuals seem to have similar information in them.

That's great info, many thanks !

Hi I did email F4CTZ: http://www.f4ctz.fr/?page_id=692 (http://www.f4ctz.fr/?page_id=692)),
about the nmea v2 gps display kit, and I got a reply from him saying that if 10 or more people want to buy the display  kit he will produce the kit again,i have asked for the price of the kit
I will post when I get the info

What's the point of this ? I mean, this is a GPSDO. I think the stats you'd want would be about timing related stuff (TFOM, FFOM, ...), OCXO status, PLL status, maybe GPS time, but why display lat/long ?

I started a display PCB for my GPSDO. It's very low priority so not sure I'll finish it, but if I do i'll let you all know. Basically it's just a PCB with a 4x20 LCD and a MCU.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 13, 2015, 09:46:17 pm
Hi,

...and the TFOM and FFOM saw in the first status command above ? Any other information ?
I just found this one.

TFOM (Time Figure of Merit) is the accuracy of the 1 PPS signal, with 0 < 1ns, 1= 1 to 10 ns, 2 = 10 to 100 ns, 3 = 100ns to 1us, ... 9 > 1ms
FFOM (Frequency Figure of Merit) is the stability of the 10MHz signal. 0 = PLL stable, 1 = stabilizing, 2 = holdover, 3 = unlocked (do not use as 10MHz out of spec)

You can use the commands SYNC:TFOM? and SYNC:FFOM? to get a description of the current state.
e.g.
Code: [Select]
UCCM-P > sync:tfom?
10-100 ns
Command Complete
UCCM-P > sync:ffom?
PLL stabilized
Command Complete

I'm trying to find other stuff and can't find the manual for this particular unit, but other symmetricom and HP GPSDO manuals seem to have similar information in them.

That's great info, many thanks !

Hi I did email F4CTZ: http://www.f4ctz.fr/?page_id=692 (http://www.f4ctz.fr/?page_id=692)),
about the nmea v2 gps display kit, and I got a reply from him saying that if 10 or more people want to buy the display  kit he will produce the kit again,i have asked for the price of the kit
I will post when I get the info

What's the point of this ? I mean, this is a GPSDO. I think the stats you'd want would be about timing related stuff (TFOM, FFOM, ...), OCXO status, PLL status, maybe GPS time, but why display lat/long ?

I started a display PCB for my GPSDO. It's very low priority so not sure I'll finish it, but if I do i'll let you all know. Basically it's just a PCB with a 4x20 LCD and a MCU.
Think about Ham activities, in  the field, really useful to have such informations. Also the F4CTZ display can help you tracking the sun and moon.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Theboel on December 14, 2015, 12:49:30 am
I like to have display for my GPSDO box because I like to see the signal strength from the satellite I receive for some situation like difficult outdoor antenna installation it will very helpful.
 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on December 14, 2015, 02:11:04 am
Yes, the LAT/LON seem to be a pretty minor thing to display compared to GPS or UTC time and date. Lock, 10MHz, 1PPS status etc is more important still. These things are not meant to be mobile but in a fixed location. Any old GPS could be used for a LAT/LON position. Once a survey is complete that LAT/LON will never change display (hopefully - but I think even earthquakes, landslides, sinkholes will take a long time to correct!  :-DD )

Now I still have to make a Nixie clock and this thing is ideal - a combined desk clock, Stratum-1 (a Ras Pi) NTP server for my network, and distributed 10MHz and 1PPS too all in one box  :-+

I warn you all, my ebay last second (microsecond?) sniping will reach a whole new level of evil I tell you! automated by my Stratum-1 Raspberry Pi Bidsniper! >:D  :-DD
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Deathwish on December 14, 2015, 02:31:31 am
I warn you all, my ebay last second (microsecond?) sniping will reach a whole new level of evil I tell you! automated by my Stratum-1 Raspberry Pi Bidsniper! >:D  :-DD

And then at the last picosecond the internet fell out, muahaha
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 14, 2015, 02:34:02 am
Hi you could fit a cheap Bluetooth board on to it and use a Bluetooth gps app on your phone
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on December 14, 2015, 02:55:02 am
Yes, the LAT/LON seem to be a pretty minor thing to display compared to GPS or UTC time and date. Lock, 10MHz, 1PPS status etc is more important still. These things are not meant to be mobile but in a fixed location. Any old GPS could be used for a LAT/LON position. Once a survey is complete that LAT/LON will never change display (hopefully - but I think even earthquakes, landslides, sinkholes will take a long time to correct!  :-DD )

Now I still have to make a Nixie clock and this thing is ideal - a combined desk clock, Stratum-1 (a Ras Pi) NTP server for my network, and distributed 10MHz and 1PPS too all in one box  :-+

I warn you all, my ebay last second (microsecond?) sniping will reach a whole new level of evil I tell you! automated by my Stratum-1 Raspberry Pi Bidsniper! >:D  :-DD

You assume ebay has accurate time, - good luck with that.

btw, here is a scope shot showing 24 hours with infinite persistence enabled comparing my Nortel GPSDO and my Trimble UCCM. So either they are both bang on 10 MHz or both incorrect. A good thing overall as the one BG7TBL GPSDO was not really running at 10 MHz.

Also I have checked on my Trimble and have never seen lower then 10-100 nsec for the TFOM

UCCM >SYNChronization:TFOMerit?
10-100nsec
Command complete
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on December 14, 2015, 03:07:44 am
Hi you could fit a cheap Bluetooth board on to it and use a Bluetooth gps app on your phone
Dave 2E0DMB
your best bet would be to look into one of the ublox alternatives. The 8m/n receivers are much more powerful than the Furuno in the Symmetricom unit. The Furuno is a 16ch unit, that can track 12. The Ublox 8 series is a 72 ch gps/glonass/beidou receiver.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 14, 2015, 04:06:21 am
Hi I meant to use your phone or tablet as a display not as a gps source
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 14, 2015, 04:16:20 am
Hi Steve can you test one of those against the BG7TBL GPSDO,
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on December 14, 2015, 04:26:02 am
Hi Steve can you test one of those against the BG7TBL GPSDO,
Dave 2E0DMB

I would if I had one, only have these two at the moment - just enough to never know which one is better!

btw, I did generate a 10.000000001 MHz signal(referenced to one of the GPSDO's) and feed it into a third channel, it didn't take long to see the error with persistence set to infinite.

I now have a 10.0000000001 MHz signal on channel 3 and will let it run for a while to see the error show up.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 14, 2015, 05:10:53 am
Hi Steve I have a  BG7TBL GPSDO with the ublox 6m, so when I get my other ones I will do a test
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on December 14, 2015, 06:25:37 am
Here is two hours with the two GPSDO's, the third channel(bottom) is a frequency generator referenced to the top GPSDO outputting 10.000,000,000,1 MHz - error of 100 microHz. So it shows how easy it is to see a small error with the scope over time. The frequency counter is also referenced to the same GPSDO as the frequency generator.


EDIT - added a third picture which is the same configuration as above except the frequency generator has been set to 9.999,999,999,8 MHz which is the approximate frequency of the original BG7TBL GPSDO, elapsed time was only 30 minutes. Within an hour it would just be a purple smear on the screen. So if you do have one this is what you can expect.

btw, with the frequency generator set to 10 MHz exactly there is zero drift as it is referenced to a GPSDO. I think that original BG7TBL GPSDO would drive me nuts - I'd always know it isn't really 10 MHz.

I wish I had the Symmetricom version of the UCCM to compare but I expect it to be similar to the Trimble as they were designed to the same specs for whatever cell system they were installed in.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 14, 2015, 01:49:27 pm
Hi F4CTZ has got back to me
if 10 kits are orderd the price would be 50 euros and 30-40 kits are orderd price will be 30-35euros that's +P&P
I have orderd the parts to make mine on vero board lcd from china will not need smt connectors,i have the pic SDIP,coming from rs tomorrow,
the bg7tbl gpsdo I have has the 16-4-2015 pcb fitted, last night I pluged in a rs232 Bluetooth serial adapter in to the DB9 nd have been running Bluetooth gps app on my android phone to see the number of sats and levels, and I have found out were I live :)
I am going to wire in a TTL level blutooth adapter to the ublox tx line to be left in the unit,
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 16, 2015, 08:55:02 pm
Hi,

@davebb: That sounds great, let us know your progress.

So, I just finished my enclosure.

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on December 16, 2015, 09:08:15 pm
Looks great - do you have more info on your distribution amplifier?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 16, 2015, 09:11:24 pm
Looks great - do you have more info on your distribution amplifier?

Thanks ;-)

Yeah, I used the DF9NP's fanout 1:10 schematic, then changed two things. If you're interested, I can provide my schematic, eagle files and so on.

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on December 16, 2015, 09:23:22 pm
 :-+ great job.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 16, 2015, 09:49:37 pm
Hi Daniel that looks really good
I fitted a Bluetooth module in the bg7tbl,the range is not very good I have put it on the back pcb panel
I wired it to the TTL tx in on the max3232 so its on the output of the microcontroller so it wont upset anything,

I got my pic16f2620 is/dip but when I try and program it I get configuration error, can you tell me are there any settings I have to change in the configuration of the program ie, oscillator etc
Thanks Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 16, 2015, 10:10:21 pm
Hi again Daniel
so is your display wired strait to the TX pin on the gps module
Thanks Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on December 16, 2015, 11:14:18 pm
I have to admit I have no real interest in the immediate GPS output of the Furuno, because better engineers than me have sorted that stuff out into the Symmetricom GPSDO with a FFOM of at least 2.

I would like to know what the TOD data packets are, like when you enable TOD EN on SER2. There is also the SER1 output which I haven't probed yet but is most likely the TOD output in binary from what others have stated.

An interesting serial request is PTIME:TCODE? - this is not listed when you issue the ? help command, but is in other Symmetricom documentation.

T1xxxxxxxxtlfrvcc
xxxxxxxx is the date and time of the next 1PPS pulse, referenced to GPS time as number of seconds since 1980/01/06 00:00:00

There can sometimes be a little delay when you issue this command, no doubt to make sure it doesn't respond too early as it is the predicted time of the next 1PPS pulse.

ETA: My ebay bidding sniper wars require such accuracy  :-DD But seriously, I suspect all the banksters "high frequency trading" must rely on this stuff.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uski on December 17, 2015, 01:03:31 am
Looks great - do you have more info on your distribution amplifier?
Yeah, I used the DF9NP's fanout 1:10 schematic, then changed two things. If you're interested, I can provide my schematic, eagle files and so on.

Hi Daniel ! Your box looks awesome, i'm jealous :-+

I could totally use your Eagle files for the splitter too. Please share ! :)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 17, 2015, 08:09:32 am
Hi Dave,

Hi Daniel that looks really good
I fitted a Bluetooth module in the bg7tbl,the range is not very good I have put it on the back pcb panel
I wired it to the TTL tx in on the max3232 so its on the output of the microcontroller so it wont upset anything,

I got my pic16f2620 is/dip but when I try and program it I get configuration error, can you tell me are there any settings I have to change in the configuration of the program ie, oscillator etc
Thanks Dave 2E0DMB

It's a PIC18F ;-)

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 17, 2015, 08:11:29 am
Hi,

Hi again Daniel
so is your display wired strait to the TX pin on the gps module
Thanks Dave 2E0DMB

Yes, since both are TTL. Pin #1 on J1 connector.

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 17, 2015, 08:17:31 am
Hi,

Looks great - do you have more info on your distribution amplifier?
Yeah, I used the DF9NP's fanout 1:10 schematic, then changed two things. If you're interested, I can provide my schematic, eagle files and so on.

Hi Daniel ! Your box looks awesome, i'm jealous :-+

I could totally use your Eagle files for the splitter too. Please share ! :)

Happy you like it ;-)

Here they are. Bear in mind that's DF9NP's work, I modified it for my personnal requirements (Symmetricom output level, power supply input voltage and filtering).

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 17, 2015, 10:27:16 am
Yes sorry I did mean 18f2620 DIP
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on December 17, 2015, 10:32:46 am
Yes sorry I did mean 18f2620 DIP
Thanks Dave
Ah, okay. Well, I have no clue about your problem. Configuration are stored inside the hex.
Is your pic programmer recognize the chip? Are you able to erase it?

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 17, 2015, 02:30:40 pm
Hi Dan
Yes I have done both,i will play with it more when the display arrives,like I say you have done a brilliant job on your unit,
The only difference is that I am usinga S/P DIL chip not a smt device,
Thanks Dave 2E0DMB 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Deathwish on December 21, 2015, 11:55:14 am
Gave up waiting for mine to come,so demanded a refund, went to aliexpress and got a trimble for £46.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: jackenhack on December 21, 2015, 05:03:05 pm
Yes, the LAT/LON seem to be a pretty minor thing to display compared to GPS or UTC time and date. Lock, 10MHz, 1PPS status etc is more important still. These things are not meant to be mobile but in a fixed location. Any old GPS could be used for a LAT/LON position. Once a survey is complete that LAT/LON will never change display (hopefully - but I think even earthquakes, landslides, sinkholes will take a long time to correct!  :-DD )

Now I still have to make a Nixie clock and this thing is ideal - a combined desk clock, Stratum-1 (a Ras Pi) NTP server for my network, and distributed 10MHz and 1PPS too all in one box  :-+

I warn you all, my ebay last second (microsecond?) sniping will reach a whole new level of evil I tell you! automated by my Stratum-1 Raspberry Pi Bidsniper! >:D  :-DD

I've just finished building a Raspberry Pi Stratum-1 NTP server. I'm currently using a U-Blox 7M GPS module, because my Trimble GPSDO's 1 PPS output have too short output pulse width.
(https://dl.dropboxusercontent.com/u/261736/Images/1pps_timepulse.png)
Seems like the PPS kernel driver needs a longer pulse to work. But I'm going to build this to lengthen the pulse, because I want to use the Trimble's output.
(https://dl.dropboxusercontent.com/u/261736/Images/ppm-schematic.png)
This will give approximately 250ms pulse which should be enough.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on December 21, 2015, 07:30:27 pm
@jackenhack. Thanks, yes the pulse width is very narrow. Thanks for that, I probably would have wasted hours debugging it  :palm:
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: jackenhack on December 21, 2015, 08:04:34 pm
@jackenhack. Thanks, yes the pulse width is very narrow. Thanks for that, I probably would have wasted hours debugging it  :palm:

Getting the 74HC123 tomorrow, so I'll keep you posted on if it works.

Added a rudimentary display to the NTP server so I could get the time, and also get some status so I know when the network goes down and it switches to GPS/PPS only. It's no Nixie clock but it's something.   :)

https://dl.dropboxusercontent.com/u/261736/Images/ntp-server-display.mov (https://dl.dropboxusercontent.com/u/261736/Images/ntp-server-display.mov)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on December 21, 2015, 11:09:09 pm
But are you taking into account the 1/4 second delay by triggering on the falling edge?

I quite like my earlier alluded to PTIME:TCODE? serial query, and then I would use an interrupt rather than polling to snatch that 1PPS just within that 10us period. Also, don't forget you have to program in the antenna delay too - use GPS:REF:ADELAY <seconds>, e.g. 25E-9 for 25ns (5 meters cable)  - ok that would help with the 10MHz more so ;)

But maybe the TOD output takes account of a lot of this. Like it should take account of baud rate, etc. No exact documentation to go on, so ???
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: jackenhack on December 22, 2015, 09:28:18 pm
But are you taking into account the 1/4 second delay by triggering on the falling edge?

I quite like my earlier alluded to PTIME:TCODE? serial query, and then I would use an interrupt rather than polling to snatch that 1PPS just within that 10us period. Also, don't forget you have to program in the antenna delay too - use GPS:REF:ADELAY <seconds>, e.g. 25E-9 for 25ns (5 meters cable)  - ok that would help with the 10MHz more so ;)

But maybe the TOD output takes account of a lot of this. Like it should take account of baud rate, etc. No exact documentation to go on, so ???

There shouldn't be a delay. The circuit resets and waits for the next rising edge. You can adjust the time with R1 and C1. With these values, you should get about 250ms.

Yup, have measured the length of my cable, even checking the speed the HUBER+SUHNER cable propagates signals and added the delay. :-)

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Deathwish on December 23, 2015, 05:09:41 pm
does anyone have the pin outs for that symmetricom units ribbon cable
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 24, 2015, 01:48:01 pm
Hi Steve
I received my trimble from China the same as yours Today 12 days to the uk,
Can You please tell me how to get the list of commands
I have treid sending ?
but that is not recognised,i can send STAT and that works,
also when I powered it on  it does output the 10mhz,i read I can change this to only output when gps is active?
and how do I change the ELV from 5deg on start up survey
Thanks Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on December 24, 2015, 03:32:33 pm
I can See most of the commands for the Symmetricom GPSDO / 10MHz, work
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on January 04, 2016, 10:13:50 pm
So i bought 2 units,  but they were not described as in good shape.
Lets see how they are, when they arrive.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 06, 2016, 09:02:04 pm
Hi The Trimble I orded came on the 24/12, I am still waiting for my Symmetricom GPSDO / 10MHz that I orded 2 days after the trimble,
the ones I orded were not advertised as working just good condition,
the trimble works fine but I did fined a solder bridge mod to reduce the output level,that I removed and now is working very well,i just need to get the antenna outside with some lmr400 coax,
 I also have picked up a Working HP 4port N-type amp with 3 ports DC blocked from china that came in 1week
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 06, 2016, 09:47:22 pm
LMR400 - you're going all out! I save the good stuff for my antenna's that connect to the ham rigs. I have two Trimble GPS antennas mounted on my tower, both use surplus RG62 coax - yep it is 75 ohms and introduces an impedance mismatch but there is plenty of signal. It seems it was even a recommended practice by Trimble in the past as a cost effective feed line choice.

btw, hope your IC7000 sale goes well(I'm on the mailing list)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 06, 2016, 11:17:30 pm
Hi Steve
Yes a bit over the top, I got 100m of ultraflex for a good price,i also have about 70m of 9913 I will use that,
I was just playing the u-blox 6m was getting 14 sats,and the trimble was getting 5-6,that was both running of the same inside antenna
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 06, 2016, 11:33:21 pm
LMR400 - you're going all out! I save the good stuff for my antenna's that connect to the ham rigs. I have two Trimble GPS antennas mounted on my tower, both use surplus RG62 coax - yep it is 75 ohms and introduces an impedance mismatch but there is plenty of signal. It seems it was even a recommended practice by Trimble in the past as a cost effective feed line choice.

btw, hope your IC7000 sale goes well(I'm on the mailing list)

Hi Steve,

Actually, RG62 (was that a typo?) is 93 ohm cable, but since it works I guess it doesn't matter!  You are correct that Trimble recommends RG6 cable.  In the manual for the Thunderbolt they basically say "Yes, there's a mismatch but it doesn't matter so quit whining and use it!" or words to that effect.  ;)  The Thunderbolt actually has an F connector for the antenna to make it easy to use CATV cable.

Ed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 06, 2016, 11:37:35 pm
Hi Steve
I am surprised The 7000 has not sold so far,i mite change some of the photos,I just wanted to show power output on HF/VHF/UHF as I know They Can Have problems,
I can not believe some people buy radios on ebay when sellers just say that it switches on and it all lights up
and that is the only test that they can do,and the radio sells for a good working price
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 07, 2016, 04:44:42 pm
My Symmetricom GPSDO / 10MHz Came today,its not good news+
I can see 3 component's have been ripped off the board c108,c52,and u25
,The Main problem is When U25 was ripped off it has damaged The Tracks on the pcb
if anyone can tell me what Value The caps are,and What U25 is and if anyone can tell me were it is wired to
as I would like to fix this
Thanks Dave 2E0DMB 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on January 07, 2016, 05:05:36 pm
U25 is the same as U24 labelled Z04B on mine

The caps I can't get any valid in circuit measurements, sorry.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 07, 2016, 05:46:50 pm
Hi Thanks Macbeth
That helps a lot
this is what I found,that it is a inverter, one of the tracks that's missing is not connected as I found out on y=the data sheet
NC7SZ04P5X

Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 07, 2016, 05:49:50 pm
LMR400 - you're going all out! I save the good stuff for my antenna's that connect to the ham rigs. I have two Trimble GPS antennas mounted on my tower, both use surplus RG62 coax - yep it is 75 ohms and introduces an impedance mismatch but there is plenty of signal. It seems it was even a recommended practice by Trimble in the past as a cost effective feed line choice.

btw, hope your IC7000 sale goes well(I'm on the mailing list)

Hi Steve,

Actually, RG62 (was that a typo?) is 93 ohm cable, but since it works I guess it doesn't matter!  You are correct that Trimble recommends RG6 cable.  In the manual for the Thunderbolt they basically say "Yes, there's a mismatch but it doesn't matter so quit whining and use it!" or words to that effect.  ;)  The Thunderbolt actually has an F connector for the antenna to make it easy to use CATV cable.

Ed

A typo indeed - that 2 got in there somewhere. I am using RG6 cable.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 09, 2016, 04:14:27 pm
I Have fitted a new inverter and played fitting different value caps in were the broken ones, and found another broken one C103 ,still not working
my cat is trying to help as well
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on January 09, 2016, 04:59:39 pm
Cute cat   ^-^
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 09, 2016, 05:53:06 pm
Hi Yes he is a good boy, always wants to see what I am doing,He will only do what he wants to do
Hi can be a pain,but I would not change Him and he is very talkative
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 09, 2016, 11:51:04 pm
TiN bought a Trimble GPSDO with the 73090 OCXO but it should be pretty similar - he took excellent high res pics you can see here:
https://www.eevblog.com/forum/repair/repair-temexspectratime-lpfrslpro-10mhz-rb-generator-%28drifting-like-mad%29/60/ (https://www.eevblog.com/forum/repair/repair-temexspectratime-lpfrslpro-10mhz-rb-generator-%28drifting-like-mad%29/60/)

Maybe they can help you find any other faults.

btw, mine also had one capacitor crushed, but it was a bypass cap so I just soldered in a 0.1 uF.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 11, 2016, 10:51:53 pm
Hi Steve They are good photos but I am trying to fix my Symmetricom, the seller did ask if I wanted a replacement,and I said yes, we will see how that goes
Thanks Dave,
I have also sold my Icom-7000
 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on January 11, 2016, 11:14:08 pm
Hi Steve They are good photos but I am trying to fix my Symmetricom, the seller did ask if I wanted a replacement,and I said yes, we will see how that goes
Thanks Dave,
I have also sold my Icom-7000
 
If it's the same seller as mine then don't waste your time. He makes you wait to the ebay limit and asks you to wait a few days extra when it's clear he didn't send a replacement out at all...

Just ask for a refund and be done with it. In fact logically there is no more reasonable option - get the refund, then just buy another one if you trust the seller. Allowing them the option to have an extra month while holding on to your money encourages them to try all their Won Hung Lo tricks of deception taught by no other than Fu Manchu himself  :box:  >:(
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on January 16, 2016, 05:37:34 pm
Also got a symmetricom today. Bought from flyxy2015. Arrived fast. It was clearly DOA, the xtal was not on the pcb but was separate in the plastic bag. Don't think it happened during shipping, packaging was fine. Also the housing of the coil next to it was damaged. Later i found a tiny cap on the pcb which had shifted and was only connected on one side.

Futher testing reveiled that the DC to DC converter doesn't work :(
These things are clearly shipped without any checking  :--
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 17, 2016, 12:25:29 am
Also got a symmetricom today. Bought from flyxy2015. Arrived fast. It was clearly DOA, the xtal was not on the pcb but was separate in the plastic bag. Don't think it happened during shipping, packaging was fine. Also the housing of the coil next to it was damaged. Later i found a tiny cap on the pcb which had shifted and was only connected on one side.

Futher testing reveiled that the DC to DC converter doesn't work :(
These things are clearly shipped without any checking  :--

Take pictures and file for a refund. As was previously stated only ask for a refund, don't let them tell you they will ship you another because they never will.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: radar_macgyver on January 17, 2016, 12:56:42 am
Possibly naive question: if so many units are arriving with components ripped off the board, etc., clearly these units have taken a beating. I can imagine they were literally ripped out of some base station equipment for scrap. If this is the case, would the OCXOs have suffered damage too? If so, how would one determine this?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 17, 2016, 01:52:28 am
Possibly naive question: if so many units are arriving with components ripped off the board, etc., clearly these units have taken a beating. I can imagine they were literally ripped out of some base station equipment for scrap. If this is the case, would the OCXOs have suffered damage too? If so, how would one determine this?

All of these surplus OCXOs, GPSDOs, Rubidium Standards, etc. are potentially junk because of the way they've been (mis)handled.  That's why they're priced at a fraction of their original value.  The only thing you can do is cross your fingers and hit the 'buy' button.  I suspect some of the sellers just ship them out and if there's a problem, they ship another.  As long as the percentage of bad units is low, everyone wins - eventually.

If an OCXO was damaged by being beat up you could see one or more of the following:
- totally dead
- off frequency
- high harmonics
- high phase noise
- oven dead
- oven stuck on
- assorted intermittents

You get the idea.

Ed

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on January 17, 2016, 08:32:17 pm
yeah, it's surplus stuff. Formally used in e-bay terms means that it should be working. But most of my gear needed work after buying, this GPS unit is quite modern for me :)

I got the serial port working and let it run for a while. It locked without problems. Compared my home-brew TXCO/GPS unit with this one on the scope. Looked good, which is more or less a confirmation that the home-brew unit is not that bad.

I need to get a better GPS antenna. Now using small ones behind a window. Not ideal.
And i would like to put a micro on the serial port to show the status on a display.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: shempe on January 20, 2016, 10:53:23 pm
My Unit arrived today, not unharmed.

Have not checked it yet.
First I need to clean it, and I am waiting for new IPA.

 
(http://i.imgur.com/3WWCRfLl.jpg) (http://imgur.com/3WWCRfL)

(http://i.imgur.com/sOOHc9Ql.jpg) (http://imgur.com/sOOHc9Q)

edit: fixt picture provider
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on January 20, 2016, 11:11:10 pm
My Unit arrived today, not unharmed.
Looks a lot like my one - the GPS connector has been ripped off the board. I can't view the higher res pics because for some reason FLICKR thinks this is "adult content" and I am not going to sign up for that.

I wish people would just use imgur.com (http://imgur.com/) which is totally anonymous, no ads, no signups and is free. Or just use eevblogs forum image upload for smaller stuff in the right format.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on January 20, 2016, 11:42:36 pm
I think they just hired some brutes to rip the cables out of these things. I mean, there is no excuse for ripping the GPS antenna MCX socket off, the cable isn't even screwed into it.

My own one had a failed 5V to 12V booster module (the TI PTN04050C). You can get them on AliExpress but they aren't cheap. I got an ebay XL6009 booster to do the job instead. But beware - If you do not supply enough amps to begin with @ 5-5.5V then it goes into some weird PSU current sinking destruction mode! In fact I can't run my board with my DP832 no matter what initial amps I set it, while it will run fine on other PSU's providing enough current is used to start it (1.6A @ 5V).  :wtf:
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: shempe on January 21, 2016, 02:38:02 pm
yes brutes ...
I looked at the pcb today and it looks like only the MCX for the GPS antenna is not there, and a ripped of cap in the lower left corner. Could be worse.
I bought a few pigtail, GPS antenna, and a few dc step up modules just in case, this should arrive in the next days.

Thank´s for the info about current sinking destruction mode I hope my old HP 6267B is up for the task.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 21, 2016, 09:40:32 pm
Hi due to the brilliant photos that shempe posted it looks as i now have mine working,it is running a Survey,when i looked at u25 to l17 in the photo i could see there was a track going to the 2 caps to the left of u25 that i had left out as my u25 inverter had been ripped off the board,
thanks Dave

Command Complete
UCCM-P > SYSTem:STATus?
-------------------------------------------------------------------------------
090-03861-03   serial number W561028299   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     2             FFOM     0
                                              UCCM-P Status[ACTIVE]

>> GPS: [phase:  1.33e-08]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 6 ____   Not Tracking: 2 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      21:27:39     21 JAN 2016
  2  27  83   40    24  23 135                GPS      Synchronized to UTC
  6  17  41   35    31  31 303                ANT DLY  +0.000E+00
 12  47  71   43                              Position ________________________
 14  43 245   42                              MODE     Survey:   13.6% complete
 25  82 332   35
 29  41 193   37                              AVG LAT  N  50:51:38.301
                                              AVG LON  W   0:56:00.451
                                              AVG HGT           +16.08 m  (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------

Command Complete
UCCM-P >

Command Complete
UCCM-P > POSSTATus
-----------------------------------------------------------------------------
1/21/2016 21:37:30
-----------------------------------------------------------------------------
 Position : LAT(N 50:51:38.202) LON(W 0:56:0.300) H(23.20 m MSL)
-----------------------------------------------------------------------------
 Geometry : PDOP(28.0) HDOP(17.5) VDOP(17.5)
-----------------------------------------------------------------------------
 Channel Status
   num of visible sats > 8
   num of sats tracked > 6
   ------ Receiver Channel State ------
     CH 0 >  SateID(2) TrackMode(pos avail) SigValue(39)
     CH 1 >  SateID(6) TrackMode(pos avail) SigValue(34)
     CH 2 >  SateID(12) TrackMode(pos avail) SigValue(41)
     CH 3 >  SateID(14) TrackMode(pos avail) SigValue(41)
     CH 4 >  SateID(25) TrackMode(pos avail) SigValue(39)
     CH 5 >  SateID(29) TrackMode(pos avail) SigValue(44)
     CH 6 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 7 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 8 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 9 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 10 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 11 >  SateID(0) TrackMode(code search) SigValue(0)
-----------------------------------------------------------------------------
  Rcvr Status(1) :
-----------------------------------------------------------------------------
  Antenna Voltage: 5088 mV,  Antenna Current: 28 mA
----------------------
UCCM-P > STATus

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [Master]
1-2. #Before ACTIVE STATUS ------------- [Master Holdover]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [NORMAL 2 MODE]
Command Complete
UCCM-P >
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 22, 2016, 11:44:34 am
Hi my Symmetricom is doing a survey when ever the power is switched off is there a command to stop this,as my trimble only did this once when i first powerd it up when i received it
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 22, 2016, 10:46:08 pm
Hi if I connect 2.1-3.6v batt to pin 7 vbck ,on the gps module would it stop the unit from doing a Survey every time it is powered off then back on,
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 22, 2016, 11:25:20 pm
Its interesting the Trimble and Symmetricom modules don't behave exactly the same being they were clearly designed to be swapped in place of each other.  Obviously when in commercial basestation cellular use they would be expected to never lose power.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on January 22, 2016, 11:53:59 pm
Indeed. Also the power input being protected with a 10A SMD fuse... WTF? I've found anything over 1.6A is good enough to kickstart it and it then drops immediately to a much lower power consumption. However, the input at the 10A fuse goes through a 8A schottky rectifier and right on to the powering up of the external GPS antenna. I guess they use much more demanding antennas than my "GPS mouse 3.3-5V" in the original application ???
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 23, 2016, 12:11:15 am
Hi Steve
yes I was surprised to see that,i would like to know that others are getting the same results as there was a lot of damage to the board,it does seem to be working well now,when I fitted a new u25 inverter ic I used kaynar wire then put hot glue over the top of u25, also I have now found the 1pps signal on both units,like you say the pulse width is short, the u-blox gps 1pps is a lot easier to see, the Symmetricom gps seems a bit more sensitive then the trimble unit
Thanks Dave
 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 23, 2016, 12:35:34 am
Hi Macbeth
Does your Symmetricom do a Survey every time it is powered off then back on
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on January 23, 2016, 12:57:34 am
davebb, Yes it does... Takes a couple of hours...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 23, 2016, 01:12:40 am
ok thanks for that, I may try fitting a batt to the pin 7 then that should do it I hope,unless it is just in the Symmetricom firmware to run the Survey after main power out,
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 23, 2016, 02:29:56 am
Other then perhaps receive sensitivity it sounds like the better unit to get is the Trimble. No high inrush current, no DC to DC boost supply to fail and it remembers where it is. My Trimble is also plenty sensitive and 12 channel, my Nortel/Trimble unit is 8 channel as is my HP 58540A. I would still like a Symmetricom to compare to but 3 GPSDO's is probably enough.
btw, they all report the same location but only the HP gets the correct elevation, both Trimble designed units are 20 meters off.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 23, 2016, 02:03:08 pm
Hi I just fitted a 3v cr2032 batt as a gps batt backup to pin 7 on the gps ,and it did not stop the unit doing a Survey after power out
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on January 23, 2016, 06:18:28 pm
Does anyone know the value(something acceptable would work) and size of c108. It is missing, and would be my first smd component i have worked with.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 23, 2016, 06:59:04 pm
Hi for c108 I used a 1nf (102) as that's what I had laying around and its working fine,
and you don't have to use a smt cap just use a std cap and solder that to the pads then use some hot glue over it
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on January 23, 2016, 07:55:27 pm
Thanks, I lost afew caps/ resistors when cleaning off the board. Ill let you know what else is missing.
im amazed how tiny the overall board is.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 23, 2016, 11:01:08 pm
Hi are you shore it was your cleaning that did it, as I had some caps missing/broken and U25 5 pin inverter was ripped of the board with the tracks,
good luck we are all here to help,spend a lot of time looking at the board and the photos on here to see if you have missed anything,
I have just made a display board to show the gps data, http://www.f4ctz.fr/?page_id=692 (http://www.f4ctz.fr/?page_id=692)
and the moded HEX file from Daniel F1RMB
I made mine on some vero board,i have just powerd it up and so far it is all working I just need to wire up the NMEA data to it from the Symmetricom gps
Let us all know haw you are getting on with your board
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on January 24, 2016, 04:49:47 am
On unit 1; replaced the cap. Powered it up, draws 2.2A @5.4v.the dc/dc converter is whining, 5v is present at the 5v test point, the ocxo is only getting 9.6v.
unit 2: there is 1 missing cap, c30, but there are 2 loose caps floating on the board. Hmm, better start looking for others.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 24, 2016, 05:50:22 am
Sheesh, they really were just tossed on the scrape pile when salvaged weren't they. Should be 10 bucks each in the condition they're in.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 24, 2016, 10:13:38 am
Hi you say that your input voltage is 5.4v,is that under load? as I found that the dc-dc do scream when just under volts,i am using a cheap adjustable dcdc powering mine so I can use a 12v supply,so I set it up with out load and when I  connected my Symmetricom  the dcdc on the  Symmetricom screamed and the output voltage wwas low like yours,so I then set it up under load and all was fine
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: hs3 on January 24, 2016, 02:01:17 pm
To satisfy my curiosity I also got one of these Symmetricom modules a while ago.

While testing I noticed that it seems to take a bit of a current spike when powering up.

Here are some examples at couple different input voltages. Power supply here was Rigol DP832 set to 3A current limit.

First 6V supply voltage:

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=196396)


5.5V supply voltage. Here the module was already warm. I think I had trouble powering it up also with 5.5V voltage in the past when it was cold. Same whining sound as with 5V when that happened.

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=196398)


5V supply voltage. Not starting, there is that whining sound from the board.

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=196400)


I have not tested how much larger the current spikes might be with a power supply without current limiting.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on January 24, 2016, 03:57:53 pm
The 5.4v is under load, i will turn it up a few hundred mV.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 24, 2016, 04:13:52 pm
Hi it should be up to voltage at that try another 100 or 200mv,reflow the solder joints on the dcdc,you will probably fine another 100mv will do it,you could allways get a cheap new dcdc adjustable buck boost new from china £1-2,

anyway I got my display working, the only thing it does not show all of my ,LON  W   0:56:00.451
what is good for us hams is it shows the locator
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on January 24, 2016, 04:57:00 pm
Hi it should be up to voltage at that try another 100 or 200mv,reflow the solder joints on the dcdc,you will probably fine another 100mv will do it,you could allways get a cheap new dcdc adjustable buck boost new from china £1-2,

anyway I got my display working, the only thing it does not show all of my ,LON  W   0:56:00.451
what is good for us hams is it shows the locator
Dave 2E0DMB

Yeah, I guess there's a bug in the original code: badly handling negative (W & S). If you want, I can build you another HEX file for testing purpose.

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 24, 2016, 05:11:18 pm
Hi Daniel
Yes please that would be brill,i wish I could do that,
Thanks Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on January 24, 2016, 05:42:25 pm
Hi Daniel
Yes please that would be brill,i wish I could do that,
Thanks Dave 2E0DMB

Here it is. Please tell me if it works, this way I can send the fix to the original author.


Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 24, 2016, 05:52:08 pm
That was fast,just going to try it thanks
,Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 24, 2016, 06:14:45 pm
Hi Daniel
All tested and working well  :-+
I just need a case now to put it all in, were did you find yours,
Thanks For your Help.
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on January 24, 2016, 06:19:51 pm
Hi Daniel
All tested and working well  :-+
I just need a case now to put it all in, were did you find yours,
Thanks For your Help.
Dave 2E0DMB

Great, this is a great news.

Well, I bought my case from an old stock in an old (closing) shop, locally (the packaging was looking from the 70's ;-) ).

BTW, where did you find your LCD display, do you have any URL ?

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 24, 2016, 07:14:24 pm
http://www.ebay.co.uk/itm/121111769872?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D121111769872%26_rdc%3D1 (http://www.ebay.co.uk/itm/121111769872?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D121111769872%26_rdc%3D1)
was not that fast, took about 1 month,

another one,

http://www.ebay.co.uk/itm/12232-LCD-Dots-Matrix-Display-Module-122x32-Yellow-Green-LED-Backlight-New/221671035094?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3D97cf7a6697c74435b9cc233dd4320cbe%26pid%3D100033%26rk%3D2%26rkt%3D4%26sd%3D121111769872 (http://www.ebay.co.uk/itm/12232-LCD-Dots-Matrix-Display-Module-122x32-Yellow-Green-LED-Backlight-New/221671035094?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3D97cf7a6697c74435b9cc233dd4320cbe%26pid%3D100033%26rk%3D2%26rkt%3D4%26sd%3D121111769872)

And one the same as yours

http://www.ebay.co.uk/itm/122-x-32-GRAPHICS-LCD-DISPLAY-MODULE-BARGAIN-fbd3a-/120837788676?hash=item1c227e5404:g:YvEAAOSwaNBUjxCb (http://www.ebay.co.uk/itm/122-x-32-GRAPHICS-LCD-DISPLAY-MODULE-BARGAIN-fbd3a-/120837788676?hash=item1c227e5404:g:YvEAAOSwaNBUjxCb)

Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on January 24, 2016, 07:32:04 pm
http://www.ebay.co.uk/itm/121111769872?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D121111769872%26_rdc%3D1 (http://www.ebay.co.uk/itm/121111769872?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D121111769872%26_rdc%3D1)
was not that fast, took about 1 month,

another one,

http://www.ebay.co.uk/itm/12232-LCD-Dots-Matrix-Display-Module-122x32-Yellow-Green-LED-Backlight-New/221671035094?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3D97cf7a6697c74435b9cc233dd4320cbe%26pid%3D100033%26rk%3D2%26rkt%3D4%26sd%3D121111769872 (http://www.ebay.co.uk/itm/12232-LCD-Dots-Matrix-Display-Module-122x32-Yellow-Green-LED-Backlight-New/221671035094?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3D97cf7a6697c74435b9cc233dd4320cbe%26pid%3D100033%26rk%3D2%26rkt%3D4%26sd%3D121111769872)

And one the same as yours

http://www.ebay.co.uk/itm/122-x-32-GRAPHICS-LCD-DISPLAY-MODULE-BARGAIN-fbd3a-/120837788676?hash=item1c227e5404:g:YvEAAOSwaNBUjxCb (http://www.ebay.co.uk/itm/122-x-32-GRAPHICS-LCD-DISPLAY-MODULE-BARGAIN-fbd3a-/120837788676?hash=item1c227e5404:g:YvEAAOSwaNBUjxCb)

Thanks Dave
Many thanks Dave.

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 24, 2016, 08:00:03 pm
No thank You,for all of your help,Daniel
can you please re write the original HEX file for the STD NMEA  SO I CAN USE IT WITH THE U-BLOX gps in the BG7TBL gpsdo so it displays all the LON in my loc,as I have another pic so I can make another one
Thanks Dave 2E0DMB
Have you stll got your ft817, I must get out with my one,
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on January 24, 2016, 08:04:37 pm
No thank You,for all of your help,Daniel
can you please re write the original HEX file for the STD NMEA  SO I CAN USE IT WITH THE U-BLOX gps in the BG7TBL gpsdo so it displays all the LON in my loc,as I have another pic so I can make another one
Thanks Dave 2E0DMB
Have you stll got your ft817, I must get out with my one,
Thanks Dave

Okay, but I'll do that tomorrow (I think F4CTZ will made a similar update on his website).

Yeah, I still have my 817, it's really a nice piece of equipment :-) (and even much more with the BHI audio DSP module).

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 24, 2016, 08:14:59 pm
Thanks No rush,
Yes the BHI dsp works very well I fitted one in my old 817 that I sold,
But then I got another 817 and I do miss the dsp, but I do have the 10w dsp speaker from them,
Are you going to gpsdo lock your 817 :-+
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on January 24, 2016, 08:19:33 pm
Thanks No rush,
Yes the BHI dsp works very well I fitted one in my old 817 that I sold,
But then I got another 817 and I do miss the dsp, but I do have the 10w dsp speaker from them,
Are you going to gpsdo lock your 817 :-+
Thanks Dave

I don't think so ;-) I fitted a TCXO-9 already, enough for HF bands ;-)

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 24, 2016, 08:45:04 pm
Yes I know but,
Same here for the 817,
like I posted I am going to fit it to my TS-2000 and I have locked my 4m transverter, very overkill,
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on January 24, 2016, 08:51:10 pm
Here is the "original" version, decoding real NMEA sentences.


Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 24, 2016, 09:08:54 pm
Thanks ,You know your Stuff,
I am only a prototype Wireman
We will Have to Talk on 20 OR 40meters
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on January 24, 2016, 09:17:49 pm
Thanks ,You know your Stuff,
I am only a prototype Wireman
We will Have to Talk on 20 OR 40meters
Thanks Dave

Why not ;-)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 24, 2016, 09:54:57 pm
Has anyone considered using TOD serial data the Symmetricom/Trimble GPSDO's can output every 2 seconds instead of the raw data?

btw, I have an FT817ND too, great rig.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on January 25, 2016, 08:14:16 am
Looks like both modules work(at least power on correctly), need to order some mcx to sma connectors.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on January 25, 2016, 11:51:54 am
That's good news
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on January 26, 2016, 11:34:38 pm
Took an old pic (16F627A) out of the stash and hooked it up with a MAX232 to the serial port. And connected an LCD.
The port we are talking to is serial2. Got the basics working using a 3.6864MHz xtal (get an exact baudrate).
I'm becoming old fart, so no arduino :) Just MPLAB, assembly and an USBEE for debugging.

For now i'm sending a command string and then dump the response on the LCD until a Carriage Return occurs. Since the GPS also replies the command string (echo), i'm only starting after the LF of the command string has passed. Took some tweaking, but it works now.

So "sync:ffom?" to the UCCM and e.g. "PLL stabilized" on the LCD.

Since i'm writing each received byte individually to the LCD after reception, i had to slow down the UCCM.
Switched it to 9600 baud. You can use only capitals: SYST:COMM:SER2:BAUD 9600.

I'm planning on using a 4 line LCD to display some interesting status lines.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on January 27, 2016, 12:18:37 am
Switched it to 9600 baud. You can use only capitals: SYST:COMM:SER2:BAUD 9600.
Are you using 8,N,1 ? I can certainly use lower case with mine. With the baud rate I quickly found I had to issue that SYST:COMM:SER2 command to drop it from 57600 default to 19200 instead as otherwise I get a lot of ascii corruption. This could just be the crappy CH340 USB adaptor and equally crappy hub I am using on my PC though  >:(
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on January 27, 2016, 12:34:45 am
What is the current draw of your units, one takes about 2.2A, while the other takes 2.6A. I think thst one might have an unhappy dc/dc converter. Its inductor gets pretty hot, when it(ocxo) is warming up.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on January 27, 2016, 11:16:59 am
Should have said "only the capitals". So you can use "SYST:COMM:SER2:BAUD 9600" instead of "SYSTem:COMMunication:SERial1:BAUD 9600". So less characters to send to the unit.

Communication works fine, either with the pic or with my pc (pentium with win98 and putty :)). The only problem i had was that there was not enough time to write a character to the LCD (too lazy to first buffer the string in an array, i'm just writing a received character to the display). So switch the unit to 9600 and there is time enough for that (i'm using interrupts, so it was not a receiver buffer overflow, but i was still writing on the display while a character was received and then already overwritten by the next one). Maybe i could have optimized the LCD routines, but this was also an option. Note the UCCM and pic must be powered at the same time; the pic assumes that the unit starts talking 57600. The UCCM does not remember a change to 9600 when powered off.

Now that the basics are working, it is only a matter of extracting the interesting data. E.g. issue POSSTAT and wait for "visible stat" and display the number behind it (until the CR). Same for "tracked".

I'll probably use LED:GPSLock? to read the status of the LED and use it to switch on a LED via the pic ;) And make a button to switch to DIAG mode and back and maybe another one to switch the output on/off. That kind of stuff. See what goodies are availabe. Note i don't care about GPS time and position; i'm only in it for the 10MHz out in my 'lab'.

No idea about current; the step-up converter in mine was DOA. I'm now doing development without powering the OCXO.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on January 28, 2016, 02:34:12 pm
Hi all,

I'm looking at this GPSDO also to put in my lab, but have a few questions:

What is the OCXO model?
It's worth to change it by an MV89A, since it's a Double OCXO?

It's only for the 10MHz, later will add an amplifier to split the signal to more equipment's,so for now no LCD.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on January 28, 2016, 03:30:57 pm
51x40x19.,it predates the rakon acquisition of c-mac. So it could either be a c-mac or temex oscillator.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on January 28, 2016, 10:41:28 pm

You can see the OCXO number in the picture on the first page. Symmetricom part.

Had a look on the internet and found manuals for similar units. Tried a few extra commands (shown with answer):
I'll have another go at it to find the useful stuff.

Don't know how useful the first two test commands are, since i get no errors without antenna and +12V supply to the TCXO. I'll probably use the error request once at start-up.

And i got an LCD with 4 lines today at the local electronics shop (dump). 4x40 :) So more than enough space to display parameters.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on January 29, 2016, 12:52:30 am

You can see the OCXO number in the picture on the first page. Symmetricom .
Its closest equivalent is the Rakon ROX5242T2. The reason for going with rakon is in the model designator 'stp' which was used on both rakon and c-mac ocxo's.  Plus the datecode, frequency output"fo" are similiar.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on January 29, 2016, 10:58:14 pm
Copied all commands out of the manual of the HP5803B to try them (not all, skipped serial settings and firmware upgrade commands for obvious reasons). Found some more interesting commands:

DIAGnostic:LIFetime:COUNt?   value returned represents 3 hours in the HP, that would be nearly 4 years for mine

GPS:INITial:DATE 2016,1,29
GPS:INITial:TIME 23,59,01
GPS:INITial:POSition N,1,1,1,E,1,1,1,0  (not sure yet what the difference is with GPS:POSition)

you can set date/time and/or position to speed up the survey. I'm planning to use it only here in the lab, so i probably poke the coordinates of my house at startup  :)

Other stuff:
GPS:POSition:SURVey:PROGress?                     +0
SYNChronization:HOLDover:DURation?                  +0.00000E+00,0
SYNChronization:HOLDover:DURation:THReshold 123
SYNChronization:HOLDover:DURation:THReshold?         +123
SYNChronization:HOLDover:INITiate                  "Data corrupt or stale"
SYNChronization:IMMediate                        "Execution error"
*CLS
SYSTem:LANGuage?                              "INSTALL"
DIAGnostic:QUERy:RESPonse?                        +123
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 30, 2016, 04:41:18 am
And if you're really adventurous, try this command

SYST:LANG "PFORTH"

It likely won't work, but if it does, it'll put you into the pFORTH interpreter that's underneath HP's Z38xx series of GPSDOs.  A few people have experimented with it, but there's very little info on it.

To exit from the interpreter the command is apparently 'halt'.  :-//

Ed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 03, 2016, 10:44:14 am
Hi today i was having a play as i just got a ftdi usb converter reddy for when i box the unit up
i just looked at
REFerence:TYPE?

and it was set to link, you can set it to GPS
WHAT should this be set to,should it be set to gps?
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on February 03, 2016, 06:36:26 pm
Was also looking at this. Made some printouts when locked:

STATUS:
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Ref Analyzing]

UCCM-P > sync:ref:enable?      GPS,LINK
UCCM-P > ref:type?         LINK

Since i have pll locked it seems not to matter that much. But i'll probably set this together with some other initial commands (initial location and 9600 baud). My assumption is that you can enable/disable GPS and LINK separately and ref type selects the primary. But i think that the other one is used as backup (so here GPS since there is no LINK connected). So i'll use:

REFerence:TYPE GPS
SYNChronization:REFerence:DISABLE LINK

But it seems to work fine without :)

I'm working on a pcb to control the UCCM (same size to put it under the unit) and drive a huge 40x4 display with status info. And then some buttons to enable/disable the output, force the output without lock etc. I'll make the oven 12V switchable (my DC to DC converter was DOA) and also the LCD backlight. So then i can switch it on for a while to achieve a decent gps lock and then switch on the oven one hour before usage or so. Save some energy while it is locking.

By the way, these alarms do something, so handy for the display:
ALARm:HARDware?     10MHz            (no 12V to the TCXO)
ALARm:OPERation?     Antenna Fail   (no GPS antenna)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on February 03, 2016, 06:48:01 pm
guido, that's an interesting project.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on February 03, 2016, 07:01:18 pm
Currently in breadboard stage. Need to make my mind up what features i want and then see if i put it on vero board or make a pcb.

Currently i'm using junk box parts: 16F627A, MAX232 and i will probably use an I2C I/O chip for driving the LEDs (not enough pins on the pic). I now have room for two pushbuttons (i'm using pin change interrupt). That's output on/off and force output. So no third one to switch between 1 and 2 PPS. But i guess i won't use that ever. There will be a switch, which will switch on a relay. With that the RS232 is switchable between the pic and a DB9 connector. So i can still hook up a pc. i'll probably also use the relay to switch power to the pic and lcd. No use having it running while there is no communication to the unit.

Guess i could use an arduino but i have more than enough (acient) parts available to do the job. And i like coding in assembler  :o
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on February 03, 2016, 07:29:31 pm
An UNO or Mini should do the job, specially the Minii at around 2€.

I guess Date, Hour, GPS: Doing fix/Nº of Sat's, the deviation from 10MHz in ppm if possible, should be enough.

If one like more stuff that is meaningful (and the GPS provide it) like operating voltages, alarms, etc, it could be enter in an menu system, where one button would toggle trough the menus.   
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 03, 2016, 08:20:19 pm
Hi Has anyone come up with how to stop the unit from doing a survey after the power has been off
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on February 03, 2016, 08:38:32 pm
Hi Has anyone come up with how to stop the unit from doing a survey after the power has been off
Thanks Dave
Nope. But I think that GPS:INITial:POSition overrides the default that seems to be somewhere in Japan and thus speed up the survey at least.

There must be some command to actually save this kind of data into FLASH, but I haven't found it yet.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 03, 2016, 09:33:23 pm
ok thanks
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on February 03, 2016, 09:51:49 pm
An UNO or Mini should do the job, specially the Minii at around 2€.

I guess Date, Hour, GPS: Doing fix/Nº of Sat's, the deviation from 10MHz in ppm if possible, should be enough.

If one like more stuff that is meaningful (and the GPS provide it) like operating voltages, alarms, etc, it could be enter in an menu system, where one button would toggle trough the menus.

I know. But i have the parts and tools available. And i also already have the software routines from other projects (lcd, serial, i2c). So it is more or less copy/paste. Just the button handling is new (but working now).

As to deviation from 10Mhz...? I would think that the output it generates is 10Mhz for what the device is concerned. Slaved to GPS to be as close as possible. It won't be off and then displaying the error. What you have is the PLL status, which you want to be "PLL stabilized" so the 10MHz out is exact (it won't a 100% but you'll get into time nuttery teritory).

Don't need menu's, 4x40 is enough to dump all relevant data :) Paid just 10 euros by the way, NOS at the local electronics shop. Just add a separate red LED which switches on if one of the alarm strings is not "NONE" or the output is switched off by the device or the status of the lock led is "off' etc. To make it highly visible that something is wrong.

I tried the GPS:INITIAL:POS (with google maps coordinates), still takes quite some time. But i did not yet compare it to a normal situation. I'm using EZGPIB in serial mode to run some commands every few seconds and log them in a file.

What you can do, if the device is stationary, is to read the coordinates it shows and then program a small micro to just issue the INIT command at power up. No need for the save command. What should also help is to set time and date apperantly.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 03, 2016, 10:05:49 pm
Hi guido
also the unit does monitor the current the TCXO is using, as when I got mine caps and ic u25  and tracks had broken, when I looked at the log record, it had logged a fault for wrong current reading from the tcxo,
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on February 04, 2016, 12:40:06 am
Yes. It is in the POSSTATUS printout at the bottom:

UCCM-P > posstatus
......
  Antenna Voltage: 4765 mV,  Antenna Current: 32 mA
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 04, 2016, 09:14:53 am
Hi guido 
I don't mean the Antenna Current: 32 mA,
I Do mean the TCXO Current, as you said that you was going to switch it,
Dave




Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on February 04, 2016, 01:20:45 pm
Sorry i misunderstood. As for this status, it is easier to just look at the HW alarm (process a single line of text). In case there is no power, it says "10MHz".
I'll probably combine both alarms and show something if one or both are not "NONE". And turn on the red LED :)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 08, 2016, 10:20:14 am
Hi I got another display for my NMEA Display, This time I got it from this ebay seller and it came to the uk in 2 weeks  :-+
http://www.ebay.co.uk/itm/12232-LCD-Dots-Matrix-Display-Module-122x32-Yellow-Green-LED-Backlight-New/221671035094?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3D97cf7a6697c74435b9cc233dd4320cbe%26pid%3D100033%26rk%3D2%26rkt%3D4%26sd%3D121111769872 (http://www.ebay.co.uk/itm/12232-LCD-Dots-Matrix-Display-Module-122x32-Yellow-Green-LED-Backlight-New/221671035094?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3D97cf7a6697c74435b9cc233dd4320cbe%26pid%3D100033%26rk%3D2%26rkt%3D4%26sd%3D121111769872)

Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on February 08, 2016, 10:47:27 am
Thanks for the URL Dave.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 08, 2016, 11:15:04 am
Thank you for redoing the HEX code
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 08, 2016, 11:29:29 am
I have got a nice Hammond case I am going to try to cut out for the display with a jig-saw and mount the leds
and sockets,i am going to use a usb rather then a 9way D,
I see that the  Symmetricom GPSDO Board uses a few alarm leds,i only want to use 2 alarm leds ,
what is the best 2 to wire to,
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 08, 2016, 12:20:04 pm
 Hi Daniel
one thing is that after some time the fix LED goes out and stays out,is this normal?
when the fix led on the display board is on,i have un-plugged the ant and it goes off,reconnected it and then it comes back on,so that bit works fine it is only when its been on some time
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on February 08, 2016, 01:23:53 pm
Hi Daniel
one thing is that after some time the fix LED goes out and stays out,is this normal?
when the fix led on the display board is on,i have un-plugged the ant and it goes off,reconnected it and then it comes back on,so that bit works fine it is only when its been on some time
Thanks Dave
I think it's because the board switch off the survey mode. I'll take a look for this (I've already made some tweaks for this in the code, but since I don't use the display led, I didn't noticed that).

Cheers.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 08, 2016, 02:07:52 pm
 Hi Daniel
ok,Thanks for the info
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on February 09, 2016, 12:26:20 pm
Mine arrived today, board was in good condition with no damage. Enclosed in a bag with the same oily film as others have described. A good cleaning with some acetone and IPA it was time to test. Hooked it up to a 5v 3A supply and it starts up at 1.8a and makes quite a loud buzzing sound from the DC-DC converter. The singing disappears or goes above my hearing range after the OXCO starts to warm up. Noticed it began to quieten around 1amp. Once the OCXO had warmed up fully and attained a lock current draw was 830ma and the board quiet.

Pressing the MACT switch as others have pointed out and it is put into some type of holdover mode and the output is 10MHZ. I wonder if the 10MHZ when the MACT switch is the OXCO undisciplined or the last point in the disciplining from the receiver. The latter would be great. The 10Mhz output  shows nothing except for some slight ripple until locked. Once it locks (took about 2 hours) then the 10Mhz output comes to life with a sine wave at 3.4 vpp and 800mv 50ohm terminated. The 1pps output works as well.

I want to hook up the RS232 but thought I should seek some advice first so as not to risk damaging the board or the PC. I assume that the output pins are receiving and transmitting at TTL levels?. If so than I can not hook the pins up to the serial port on my computer with out level shifting?.  I have one of these RS232 to TTL boards. Would this be what I need to do. Although it doesn't have a BT? pin. Or can I just hook it straight into the serial port connector on the PC.

Quote
There is a console port (RS232 levels, and it's possible to tap into 3.3V signals before the level shifter chip, some cousin of MAX3232) which I connected to a DB9 port for diagnosis, I didn't make a hole for it yet since I'm not sure I'll keep it a DB9 or I'll put an integrated RS232-to-USB converter or even a small LCD with an arduino or similar, showing basic status information. But the LEDs are mostly enough.

GPSDO  PC

RX->TX
TX->RX
Gnd->Gnd
BT->??
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on February 09, 2016, 12:33:50 pm
The serial port on the board is at RS232 level, so you can hook it up to your pc directly (Just RX, TX and GND). I have no idea what BT is.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on February 09, 2016, 12:53:04 pm
Thanks, BT is the silkscreen label beside the pin on the GPSDO, or maybe it is RT for RST?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on February 09, 2016, 01:15:52 pm
Thanks, BT is the silkscreen label beside the pin on the GPSDO, or maybe it is RT for RST?

Ok, I can't remember seeing that, but anyway leave it unconnected.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on February 14, 2016, 06:47:19 pm
Anybody got some recommendations on the power supplies? As the boost converter was broken on mine, i turned it around:

A mains to 12V 5A switcher (delta NL), with 5mVrms/20mVp-p ripple and 70mVrms/100mVp-p noise (BW=20MHz).
This will power the TXCO and an LM2676 based module (fabrimex) set for 5V (Ripple: 100mV @ nominal) It is 3.5A max, but i'll be using 1A or so (depending on the backlight of the huge lcd). This will power the UCCM PCB and my own electronics (pic, max232 and lcd). It's all based on parts i already have available.

I made a nice pcb to fit under the UCCM pcb. Same dimensions. I'm just wondering about the noise from the switchers affecting the 10MHz out. E.g. i could set both suppliers to a higher voltage output and add some low-drop regulators.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on February 14, 2016, 08:40:43 pm
@ Bryan : On mine when unlocked( I have 2 units) one reads 9.99999991MHz, while the other reads 9.9999992MHz.so reasonably close to the correct frequency.
@ guido : the ocxo should use less than 1amp of current. Not sure of the draw on the 5v rails.
Though it shoud be able to be powered with a heatsinked ldo.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on February 15, 2016, 07:15:48 pm

The UCCD without boost convertor for the TCXO is some 200mA. The LCD backlight 220mA and the rest some 30mA. So adding some LDOs should be possible.

The TCXO is some 8W (ROX5242T2), so 0.67A when warming up (say 1A). Also do-able i guess.

The big question, will it be an improvement for the 10MHz output. Another option would be to filter the output :)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on February 15, 2016, 09:23:22 pm
Some pictures. This is how it arrived. I was lucky that all the connectors were there. The boost convertor is now removed as it was kaput.

(http://members.home.nl/baltusg/UCCM1.jpg)

The ongoing project. Here the micro is communicating to te UCCM and is putting the sync:ffom? answer on a small LCD.
On the breadboard a pic and max232. The other pcb is my pic programmer  ^-^

(http://members.home.nl/baltusg/UCCM2.jpg)

The current pcb design with only the switcher. My pcb software is acient, so i have to do my own 3D rendering :-DD But there are good reasons to keep using it. Nearly all parts are from the junk box.

(http://members.home.nl/baltusg/UCCM3.jpg)

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: hs3 on February 15, 2016, 09:43:39 pm
I have seen several mentions about the boost converter being broken in these Symmetricom boards. I'm curious how did the broken boost converter behave? What happened when you tried to power on the board?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on February 16, 2016, 02:31:28 am
Does anyone know if there is a command to change the Satellite signal strength parameters. In Lady Heather with my Nortel I can adjust the AMU value to pick up satellites that don't have a strong signal. I think the equivalent for these units is the sigvalue(). Unfortunately I am on the ground floor of a condo facing North. It is tough to see more than 2 or 3 birds in the sky with this unit. The survey took me a whole day. Fortunately the elevation mask is at 5 degrees (default)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 17, 2016, 08:36:57 pm
Hi guido
are you going to post the diagram and hex code for this when your done developing all of this good stuff
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on February 18, 2016, 06:35:39 pm
I could. But it requires a 4x40 display. Would be good if anyone has an opinion on my question (?).
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on February 24, 2016, 06:54:04 am

An interesting serial request is PTIME:TCODE? - this is not listed when you issue the ? help command, but is in other Symmetricom documentation.


Macbeth:

Do you have a link to the other Symmetricom documentation. Would be interested in other commands that this board can utilize.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: jackenhack on February 24, 2016, 08:00:26 pm
I'm doing the finishing touches of my quick hack for getting status from my Trimble GPSDO (with the weird UCCM-P > prompt.) I'm using the front PPS output from one of the serial port to trigger an interrupt so I can synchronise the clock. I can then check the number of "ticks" and adjust everything synced to GPS time. Next up for implementation is to save the location after a survey and if the GPSDO resets, the controller automatically restores the coordinates from EEPROM. My version doesn't seem to store the survey data. Probably a unit where there was continuous power.

And naturally it dims the 7-segment LEDs at night and increases it in the morning.  :)
The cutout for the displays are really a botch job, but thankfully the box is dark so you have to get really close to see it.

(https://dl.dropboxusercontent.com/u/261736/Images/trimble-gpsdo-controller.jpg)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on February 26, 2016, 04:37:30 pm
Hi, all
Seeking connection assignment and everything in documentation (Schematics, assignment RS232 ...) for this motherboard :
http://www.ebay.de/itm/Used-SYMMETRICOM-UCCM-GPS-10MHz-Frequency-Time-Receiver-OCXO-/121761130751?hash=item1c598768ff:g:WZUAAOSw5ZBWF9jf (http://www.ebay.de/itm/Used-SYMMETRICOM-UCCM-GPS-10MHz-Frequency-Time-Receiver-OCXO-/121761130751?hash=item1c598768ff:g:WZUAAOSw5ZBWF9jf)

For info I would be grateful !
Greeting, Dieter
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 26, 2016, 05:24:18 pm
Hi read the 1st page and see the photos, all of the info is there
please ask again if your not shore
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 26, 2016, 06:02:18 pm
Hi Dieter , you may well have to fix it, but there are plenty of good photos on here
if it does not work the seller will tell you that he will send you another one, but he does not send it, you will have to put a clame  in with ebay, don't let me put you off as when they are working they work well
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ZigmundRat on February 28, 2016, 12:50:30 am
Could one or two of you guys please issue the DIAGnostic:LOG:READ:ALL? command and post the output? Maybe pastebin it if it's too long. My just received unit does not seem to be doing well, as all I receive is:

UCCM-P > DIAGnostic:LOG:READ:ALL?
Log status: 10 entries

L1:1980-01-06 00:07:11:Log cleared
L2:1980-01-06 00:07:11:SYST:PRESET performed
L3:1980-01-06 00:00:02:Power On [reset switch]
L4:1980-01-06 00:00:03:FPGA VCXO Alarm
L5:1980-01-06 00:00:03:OCXO Alarm
L6:1980-01-06 00:00:03:Funct Fail code: 00000208
L7:1980-01-06 00:00:03:Funct Fail OCXO curr: 201 mA
L8:1980-01-06 00:00:03:Funct Fail PDOP: 0.00
L9:1980-01-06 00:00:03:Funct Fail sat count: 0
L10:1980-01-06 00:00:03:Funct Fail TRAIM: 0 0
Command Complete

Status doesn't look too happy either:
UCCM-P > status

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [Alarm]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warmup]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [LINK0]
2-4. #Current Reference Status --------- [NOT SELECTED]
     #GPS STATUS ----------------------- [Unavailable]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ 10MHZ ]
     #Bad Quality ------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
Command Complete

Unit is running off solid 5V supply, good 3.3v out of the regulator and 11.98v on the OCXO. EFC is almost 0 and stuck there though. No GPS fix either. How long did it take to establish an initial fix? Antenna is good (I moved it from another GPSDO).

Note that this is not my first GPSDO, and I have 5 others currently running.

Thanks!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on February 28, 2016, 12:54:01 am
Hi

The "FPGA VCXO alarm" looks like the key. If it's not in range (EFC is pegged), nothing is going to be happy.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ZigmundRat on February 28, 2016, 01:03:55 am
Bob - I agree that doesn't look good. But I don't know if that's a transient startup error that is normally seen, or what. Hopefully we'll see some other logs and get some idea of what's normal and what's not. I'd like to quickly identify if this is a bad unit or not so I can get replacement/refund/credit if necessary.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on February 28, 2016, 01:09:53 am
Bob - I agree that doesn't look good. But I don't know if that's a transient startup error that is normally seen, or what. Hopefully we'll see some other logs and get some idea of what's normal and what's not. I'd like to quickly identify if this is a bad unit or not so I can get replacement/refund/credit if necessary.

Hi

If it runs for 5 minutes and still shows the FPGA VCXO alarm, its toast. The VCXO has a *much* wider range than the OCXO (after a few minutes warmup). There is no way it will unlock simply because the GPS has not done it's thing yet.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 28, 2016, 01:37:58 am
Hi I had this fault and I had some caps missing and U25 was ripped of the board , there are some very good photos that helped , good luck
Dave

see this page

 https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/75/ (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/75/)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 28, 2016, 02:01:46 am
Hi yes you have a bad unit , fly seller will tell you he will send another one but he will not send,tell him you want a refund, open a case with ebay, he asked me to close the case I opened as he said  he had sent another one,
I did not close the case, and ebay refunded me from his account , and the replacement unit never did arrive ,
still I did get the broken one working, as I put on a new u25 inverter chip and caps
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ZigmundRat on February 28, 2016, 06:34:36 am
I can confirm that it is toast. U25 is missing, ripped off the board. missing pads, etc. Also L17 but the pads are still there, and C45 is attached by one pad only. In the event that I am stuck with this, what was the original U25? I can't make out any part number in the picture and of course mine is missing :) Did you document your fix? I can make out the traces and where they go (thankfully does not look like directly to any vias) but would be nice to have confirmation. I don't imagine L17 is critical.

Message sent to the seller. I'd rather not have to repair it. We'll see what happens...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on February 28, 2016, 08:55:22 am
Hi Dieter , you may well have to fix it, but there are plenty of good photos on here
if it does not work the seller will tell you that he will send you another one, but he does not send it, you will have to put a clame  in with ebay, don't let me put you off as when they are working they work well
Dave
Thank you for your reply !
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 28, 2016, 09:03:18 am
 Hi U25 is, NC7SZ04P5X
 . Wired it up with 30awg single stand mod wire, I used a meter and found that what tracks I had left went to 
U25 is a 5 pin inverter chip
Only 4pins connected
Pin 3 of the chip goes to gnd,
Pin 2 of the chip goes to the round test point to the right of u25 writing that is also connected to the blue resistor to the Right of u25, top pad of the resistor,
Pin 4 of u25 goes to the bottom pad of that resistor,close to
The edge of the board,
Pin 5 of u25 is vcc, goes to right pad of L17, it looks as L17
Is there to filter the power
Then when it worked I then used hot glue over u25 as I only
Had one pad holding it.
Good Luck.
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 28, 2016, 09:16:12 am
See page 4 for good photos of the board
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on February 28, 2016, 09:28:35 am
Hopefully we'll see some other logs and get some idea of what's normal and what's not.

You already found out what the problem is but I posted a 'normal' log here:

https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg819369/#msg819369 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg819369/#msg819369)

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 28, 2016, 09:34:34 am
this is what I also found,

Hi due to the brilliant photos that shempe posted it looks as i now have mine working,it is running a Survey,when i looked at u25 to l17 in the photo i could see there was a track going to the 2 caps to the left of u25 that i had left out as my u25 inverter had been ripped off the board,
thanks Dave

Command Complete
UCCM-P > SYSTem:STATus?
-------------------------------------------------------------------------------
090-03861-03   serial number W561028299   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     2             FFOM     0
                                              UCCM-P Status[ACTIVE]

>> GPS: [phase:  1.33e-08]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 6 ____   Not Tracking: 2 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      21:27:39     21 JAN 2016
  2  27  83   40    24  23 135                GPS      Synchronized to UTC
  6  17  41   35    31  31 303                ANT DLY  +0.000E+00
 12  47  71   43                              Position ________________________
 14  43 245   42                              MODE     Survey:   13.6% complete
 25  82 332   35
 29  41 193   37                              AVG LAT  N  50:51:38.301
                                              AVG LON  W   0:56:00.451
                                              AVG HGT           +16.08 m  (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------

Command Complete
UCCM-P >

Command Complete
UCCM-P > POSSTATus
-----------------------------------------------------------------------------
1/21/2016 21:37:30
-----------------------------------------------------------------------------
 Position : LAT(N 50:51:38.202) LON(W 0:56:0.300) H(23.20 m MSL)
-----------------------------------------------------------------------------
 Geometry : PDOP(28.0) HDOP(17.5) VDOP(17.5)
-----------------------------------------------------------------------------
 Channel Status
   num of visible sats > 8
   num of sats tracked > 6
   ------ Receiver Channel State ------
     CH 0 >  SateID(2) TrackMode(pos avail) SigValue(39)
     CH 1 >  SateID(6) TrackMode(pos avail) SigValue(34)
     CH 2 >  SateID(12) TrackMode(pos avail) SigValue(41)
     CH 3 >  SateID(14) TrackMode(pos avail) SigValue(41)
     CH 4 >  SateID(25) TrackMode(pos avail) SigValue(39)
     CH 5 >  SateID(29) TrackMode(pos avail) SigValue(44)
     CH 6 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 7 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 8 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 9 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 10 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 11 >  SateID(0) TrackMode(code search) SigValue(0)
-----------------------------------------------------------------------------
  Rcvr Status(1) :
-----------------------------------------------------------------------------
  Antenna Voltage: 5088 mV,  Antenna Current: 28 mA
----------------------
UCCM-P > STATus

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [Master]
1-2. #Before ACTIVE STATUS ------------- [Master Holdover]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [NORMAL 2 MODE]
Command Complete
UCCM-P >
Modify message
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 28, 2016, 01:07:47 pm
Hi again
take photos of all the missing and damage parts/board and put them on ebay, this will help you when getting your money back from ebay, as the seller will not send a replacement, he says he will, do not believe him
get a refund, but do try and fix it, u25 is very small but you can do it,
get a flux pen to help with your soldering.
let us know how you get on.
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ZigmundRat on February 28, 2016, 09:12:37 pm
The seller responded, requested pics which were sent along with the diag log via eBay message. No further reply yet but I'm GMT-5 and he's in China so not worried at this point. In the mean time I'm investigating repair. I found a board with a donor Z04 so I will make an attempt. Nothing to loose here at this point. Thanks everyone for the tips, log copies and all the info!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on February 28, 2016, 09:53:25 pm
Hi

We are past the holidays in China so it's reasonable to expect a reply. Earlier this month a long delay might be the expected thing. If there is nothing back fairly soon, I'd escalate the issue.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 28, 2016, 10:08:00 pm
Hi
good luck, glad you had the chip on an old board,like I say in one of my posts there is a very fine track that goes to the 2 caps to the left of u25 that was also damaged on my unit,
good luck.
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on February 29, 2016, 12:24:07 am
If the seller is STILL selling these as good working boards, despite all the feedback he has been getting, and his ridiculous "why u not go fix it? u can fix cheap! jus' need soddering iron!?" then I don't think anyone should worry about obtaining ebay refunds. Just don't bother with the ebay option like I and many others have done in allowing him to send a replacement because he won't, he is just biding his time and hoping for ebay guarantee to time out.

Having said that they can be made good. Just order two and end up paying for one maybe?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ZigmundRat on February 29, 2016, 03:55:11 am
I find it curious that it was the same U25 an L17 that got ripped off (although I also had two other caps missing). Curious but serendipitous as I think it made sharing info easier. Thanks to davebb and everyone for the assist. Attached images of the before and after. Not my best work, but for crying out loud I used a .4mm tip and it was still too big :o ! It will have to do. My diag log now reads:
UCCM-P > DIAGnostic:LOG:READ:ALL?
Log status: 10 entries

L1:1980-01-06 00:01:20:Log cleared
L2:1980-01-06 00:00:02:Power On
L3:1980-01-06 00:00:37:Survey mode started
L4:1980-01-06 00:01:53:Time set to GPS
L5:2016-02-29 00:37:28:Time set to GPS
L6:2016-02-29 00:39:56:GPS lock started
L7:2016-02-29 02:35:42:Position hold mode started
L8:2016-02-29 02:35:42:Lat: N,+41,+37,+34.0
L9:2016-02-29 02:35:42:Long: W,+70,+39,+27.2
L10:2016-02-29 02:35:42:Height: +105.7
Command Complete
UCCM-P >

That's a little better!

AFA the seller: I didn't buy a 'for parts or as-is' piece of gear. There needs to be some accommodation.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on February 29, 2016, 11:11:22 am
that brilliant news :-+
it is strange it was the same u25, have you tested the 10mhz out
its good to help, as people have helped me,
my next project is to find a job? as I have gadgets to buy and bills to pay
Good luck Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Gork on March 04, 2016, 08:48:09 am
Hi
Thanks for an excellent thread.  Very good info.
I bought a Symmetricom GPSDO from ebay. Same seller as others bought from. Seems like i was lucky, as mine was complete, including oil.  :)
After cleaning i tested it, and it seems to work ok so far.  Ordered a cheap GPS mouse with SMA conn which seems to work ok.

Now i need to find out about the LED on the pcb, DS1-DS4. DS3, and DS4 are dual LED.
Do anyone know what function the LED's have ?  I can only find marking for DS3, which is ALM and ACT.



Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: haydenph on March 04, 2016, 10:35:16 am
Hi All,
I have been reading this thread with interest. I want to get a few of these boards, however I want to make sure they will be suitable for my application.

In one of the previous posts @davebb noted that the units go into a survey mode every time they are powered up. Someone else mentioned this is 2 hours. Does the OCXO onboard when warmed up output 10MHz? Or do I have to wait 2 hours for the GPS to do it's thing before I get a 10MHz output.

Also if GPS fix is lost, does the OCXO then take over until GPS is re-established?

Also does anyone recommend the Trimble units over the Symmerticom? The trimbles are a bit more expensive, but seeing most are the same seller, do they come busted up?

http://www.ebay.com/itm/Used-10MHz-Trimble-65256-GPS-OCXO-Precision-Clock-circuit-board-oscillator-/111770391613?hash=item1a0608d43d:g:dzcAAOSw9r1V9ORq (http://www.ebay.com/itm/Used-10MHz-Trimble-65256-GPS-OCXO-Precision-Clock-circuit-board-oscillator-/111770391613?hash=item1a0608d43d:g:dzcAAOSw9r1V9ORq)

My application only requires a stable 10MHz output. I require a 10MHz reference for a transmitter that is stable enough to keep it on frequency within 1Hz or so @50MHz. Obviously if it takes 2 hours every time the power goes off (not that it would under normal operation), this could be a pain.

Thanks


 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 04, 2016, 12:18:06 pm
Hi it will output 10mhz without gps fix , you can press the mach button
the gps is not doing the 10mhz it is the OCXO that gives the 10mhz, the gps  is linked to pro/pll to ajust frq of ocxo,
if you loose gps fix it goes into holdover to hold it stable,
if you get the Trimble unit,it only does survey mode once so it will not do it again after restart, so go with the trimble,
has your radio got 10mhz input or are you using a board to convert to the radios ref
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: haydenph on March 05, 2016, 10:43:41 am
Hi Dave,
Does the MACH button require pushing and holding? Or just a single press enables the 10MHz output?

OK on the trimble, that sounds good, but more expensive.

No this radio is a repeater for 6M with a 12MHz reference. I've done some calculations in the EPROM data for it to work with 10MHz.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on March 05, 2016, 10:52:39 am
Hi Dave,
Does the MACH button require pushing and holding? Or just a single press enables the 10MHz output?

OK on the trimble, that sounds good, but more expensive.

No this radio is a repeater for 6M with a 12MHz reference. I've done some calculations in the EPROM data for it to work with 10MHz.


I may be wrong, because I haven't thoroughly tested it but the MACH button does not do appear to do anything to the 10Mhz output as long as a antenna is detected and a satellite is in view. If the antenna is disconnected the Mach button when connected will output a 10Mhz signal, or when it is trying to do a survey. Not sure what it will do if it is in holdover?.

Note, you can also set the Mach button operation with software as well..
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: bseishen on March 08, 2016, 06:14:28 pm
Thank you all for all your information!. Just got my Symmetricom module in cant wait clean up all the oily slime off of it and to fire it up. Picked up a 19" video distribution amp dirt cheap that is basically empty inside. Will post some pics when its complete.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 08, 2016, 06:54:44 pm
Hello
I have a LCD of F4CTZ http://www.f4ctz.fr/?page_id=692# (http://www.f4ctz.fr/?page_id=692#) recreated what setting do I configure ??
I get no data displayed ?
where the signal for the display is tapped ?
Pin assignment GPS RX ?
 for example: SYST:COMM:SER2:BAUD 9600

Please Help, greeting Dieter
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on March 08, 2016, 07:41:21 pm
The LCD seems to be for decoding NMEA, some people connected the NMEA output from the GPS module to a decoder.

But the SER2 port is for communicating with the whole module, not the GPS receiver. There is no NMEA output on that serial port, you can issue the commands found in this thread. E.g. SYST:STAT?

It is also RS232, so if you connect a processor without RS232 chip it won't like that. Did not check, but i guess it's +/- 12V and not 0-5.


PS, waiting for the pcb from China  :)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 08, 2016, 08:40:18 pm
Yes it is 9600 you have to take it from the GPS module tx pin also have you changed the resister and transistor and Hex file as in previous post
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 08, 2016, 09:45:06 pm
I need to display on the bottom of the board directly on the gps rx connect?
(http://)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ZigmundRat on March 08, 2016, 09:54:13 pm
The MACT button is momentary. As I recall, when I pressed the MACT button before I had the oscillator locked to GPS, I got output. It was not exactly 10MHz, a bit off, and remained off even after GPS lock. OCXO was warmed up but frequency stayed the same. A SYST:PON reset the unit, and since everything was warm it synced up quickly and then the 10MHz was on frequency. It's almost like it locked the DAC voltage (but I didn't check).

The 4 pin serial port is RS232 with RS232 like levels. There is a level translator on the board. So you must use a real serial device - a TTL level adapter will not work on that port. I have not looked at the ports on the high density connector.

A couple tips for improving the operation of these units (at least the Symmetricom ones). Power up the unit and let it do it's survey and get all nice and stable. (Make sure SYST:STAT? shows Position MODE Hold). Then issue a GPS:POS:HOLD:LAST? command. The output will be your position:

UCCM-P > GPS:POSition:HOLD:LAST?
N,+42,+34,+3.40880E+01,W,+74,+39,+2.72220E+01,+1.10340E+02
Command Complete
UCCM-P >

The output is conveniently in the form used to manually set the position. Use these values in the future to skip the survey. We will also want to set some other parameters to optimize the operation. What you do is send the UCCM a series of initialization strings. I've posted the ones I use below. Send them with a terminal program, a micro-controller, whatever.

SYNC:REF:DISABLE LINK
SYNC:REF:ENABLE GPS
REF:TYPE GPS
OUTP:TP:SEL PP1S
GPS:SAT:TRAC:EMAN 20
GPS:POS N,+42,+34,+3.40880E+01,W,+74,+39,+2.72220E+01,+1.10340E+02

What all this does is turns off the other timing sources (which are unconnected but could still have influence) and using only GPS. It also makes sure the PPS output is 1 PPS and not 1 PP2S (1 per 2 seconds). The satellite elevation mask is change to 20 degrees to avoid multipath and other anomalies from satellites near the horizon. This improves the timing and frequency stability. Finally we set our position, which will skip the auto survey. Note that it doesn't seem to really like slamming the commands in. So wait for the UCCM prompt to come back before sending the next command.

I would bet there's a way to apply battery to the board and avoid all this, but I don't know what it is yet. It's easy enough to do this with a micro or just a script, but still slightly annoying.

Finally, here's a plot of the stability. Don't take it as gospel, it's just one sample.

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=206950;image)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 08, 2016, 10:02:15 pm
Hi

I would like to join the club please... not sure what the pin-outs are.... so I'm off to read this thread from start to finish.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on March 08, 2016, 10:23:37 pm
All of your useful pinout info is in this thread. Just make sure your psu can supply at least 2A.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 08, 2016, 10:58:32 pm
OK.  I've caught up with the thread...

on my board L20 is detached but present so I can reflow that back on

also the GPS antenna connector is missing as per shempe's board

There is a curly wire coming out of the GPS receiver which has a connector which is unplugged but hovering above J6.

Do I need to plug it back into J6 and look to source a GPS antenna connector to replace the missing one or can I just plug directly into the curly whirly wire?

From the thread it looks like you apply +5V to F1 as it comes in from the first pins of the ribbon cable.  Presumably GND supply to the top of C11 which is sitting across the supply.

There is mention of various bits of regulator circuitry not working... are there good points to test for voltages to see if these are working on my board?

Thanks in advance
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on March 08, 2016, 11:17:24 pm
@Nivag - You want to take the antenna connection from the board, because the board provides the power to your active GPS Antenna and the monitoring too.

I happened to have a connector available from an old duff GPS module and hot aired it on with some leaded solder and flux, but you may find it easier to just solder some coax to the centre pin and shield connections going to an external SMA, MCX, BNC or whatever connection your GPS antenna requires.

Quote
There is mention of various bits of regulator circuitry not working... are there good points to test for voltages to see if these are working on my board?

The top left of U14 is a pin marked PWR - this should be around 12V for powering the OCXO from the boost converter. There are also plenty of labelled testpoints for +5, +3.3, etc.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 08, 2016, 11:20:04 pm
because the board provides the power to your active GPS Antenna and the monitoring too.
I was wondering if that might be the case.  Thanks!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 09, 2016, 12:37:06 am
These posts are getting better great info from  :-+ZigmundRat  , can anyone write some code for a pic micro so at switch on the pic will write this info to the unit
SYNC:REF:DISABLE LINK
SYNC:REF:ENABLE GPS
REF:TYPE GPS
OUTP:TP:SEL PP1S
GPS:SAT:TRAC:EMAN 20
GPS:POS , we can change to our pos
I know it will be TTL so we can feed that in after the rs232 converter @
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 09, 2016, 01:00:31 am
Hi SHF
yes that is correct it is pin-3 that is the pin next to your Square Pin
you also have do these changes that Daniel f1rmb posted

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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)

« Reply #18 on: December 14, 2015, 02:23:52 AM »


Quote

 



Quote from: davebb on December 14, 2015, 02:07:09 AM

Hi Daniel
Could you please The modified Hex code/File as I would like to build this display,
you say the output is on pin 2 is that in rs232 or TTL level?
Thanks Dave 2E0DMB




Yeah, sure.

The level is TTL.

On the display module, you have to change two components:
T1 from 2N2222 to MMBT2907 (or equivalent), and the base resistor R3, from 10k to 4k7.

Cheers.
---
Daniel

* F4CTZ-GPS_Display-Symmetricom-Furuno.hex.zip (36.55 kB - downloaded 32 times.)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 09, 2016, 01:17:03 am
SHF , PIN 3 IS GPS TX
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Mr.B on March 09, 2016, 04:06:26 am
Bookmarked.
Thanks to everyone here for all the information.
Off to order my board and antenna.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 09, 2016, 03:58:58 pm
Thank you for your answers !!
Unfortunately, the display is still not what I did wrong?(http://)
Display on 9600bd and connected to pin 3 on the GPS TX (black cable)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 09, 2016, 04:06:25 pm
Did you connect your ground
and change the components and reprogram your pic
also the new transistor collector and emitter go the other way round(I made that mistake)
Dave 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 09, 2016, 04:28:33 pm
I still had data on the pic with the PNP tran fitted the wrong way round it just did not read it,it is inverting the signal, what transistor did you fit?
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 09, 2016, 05:17:42 pm
Thanks Dave
Have 2N2222 NPN removed and installed a BC327 PNP, is still not, must look further....
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 09, 2016, 05:38:18 pm
did you change e,b,c, to c,b,e when you fitted the tran
did you program the pic with the new hex from Daniel
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 09, 2016, 06:58:44 pm
Hi Dave
what is the correct hex file?

--> 10mhz_gps.X.production.hex.zip
or
--> 10mhz_gps.X.production-NMEA.hex.zip

or  http://www.f4ctz.fr/?page_id=692# (http://www.f4ctz.fr/?page_id=692#)
 --> Afficheur-GPS-V2.22-HEX
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 09, 2016, 07:07:32 pm
 This Is the one that Daniel did for me and it is working well

* 10mhz_gps.X.production.hex.zip (37.77 kB - downloaded 31 times.)
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 09, 2016, 07:09:27 pm
what one have you got programed in,
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 09, 2016, 07:36:35 pm
you need to change R3 to 4K7 ohm
and T1 the emitter and collector needs to be changed , opposite what it would be with the 2n2222
Dave 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 09, 2016, 07:55:00 pm
OK, Thanks Dave

I hope now it is right(http://)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 09, 2016, 08:03:02 pm
I currently have the Afficheur GPS V2.22-HEX in PIC
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 09, 2016, 08:30:24 pm
that could be your problem,
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on March 10, 2016, 06:16:46 am
Hi,

   Sorry, I'm really busy with my new job.
 
The official 2.22 has been released 2/3 weeks ago, and it just contains the negative coordinates patch I've sent to F4CTZ (thanks to Dave, who raised this problem).
I suggest you to use the version that Dave mentioned you.

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 10, 2016, 08:00:36 am
GOOD morning
SHF
I am using for T1 PN2907
Check that you have the display board set to 9600
Good luck
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 10, 2016, 08:39:57 am
Hi SHF
Can you take some close up photos of your board top and bottom side, so I can have a good look
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 10, 2016, 09:11:30 am
I'm trying to figure out how to route the LEDs to the front panel...

There seem to be four LEDs... DS1, DS2, dual DS3 (ACT/ALM) and dual DS4.

I'm not sure of the wiring on these but there do seem to be some test points....

Above DS1 to via
Above DS2 (might be GND?)
Between DS3 and R79 & R80 (above R79 & R80)
Between DS4 and R72 & R73

I obviously want to minimise the number of wires to the front panel.  Looks like the all go to ground via 220 ohm resistor?

Any suggestions?  Did you remove the on-board LEDs?

Thanks in advance
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on March 10, 2016, 09:27:44 am
Nivag, normally the test points are label as TPxx, where xx is the number of the test point.

On the first picture there is one test point TP14 (+3.3V), just above and on the right of R79.

So the DSxx could be something else.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 10, 2016, 04:06:31 pm
Thanks Dave, the problem was the HEX file, now have the 10mhz_gps.X.production.hex.zip the PIC, it's running great.
Thanks again for your excellent help !!!!  :-+ :-+ :-+ :-+
a very good forum here!  :-+ :-+
Greeting, Dieter
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 10, 2016, 05:06:44 pm
That's great
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 10, 2016, 06:27:06 pm
Hi Dieter
You know you now have to post a photo of it working, ITS THE LAW  :-+
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 10, 2016, 08:15:43 pm
GPS- Display working  :) :) :) :) :)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 10, 2016, 09:16:46 pm
Nivag, normally the test points are label as TPxx, where xx is the number of the test point.
The copper circular pads are good potential test points too... don't turn it on... probe it!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 10, 2016, 09:22:30 pm
That's good I bet you were getting :rant: with it
whats the 8pin chip a reg?


we have Daniel to thank for modding the HEX
 :-+ :-+ :-+ :-+ :-+
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 10, 2016, 09:53:56 pm
8 pin chip is ICL7660 for -5V for the LCD, the normal voltage divider is not enough for my display !
Daniel I also thanks for the good HEX File  :-+ :-+ :-+ :-+ :-+
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 11, 2016, 07:45:52 am
OK what display did you use?
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 11, 2016, 08:05:33 am
Is only one side of the U2 RS232 level converter chip used?  i.e. Just RS232 interfacing to the pins on the header J5?

Ideally I would remove/disable U2 and use TTL levels.

Thanks in advance
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 11, 2016, 01:42:39 pm
Hi, my LCD Type: EA DIP122-5  http://www.lcd-module.de/fileadmin/eng/pdf/grafik/dip122-5e.pdf (http://www.lcd-module.de/fileadmin/eng/pdf/grafik/dip122-5e.pdf)

Dieter
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 11, 2016, 07:20:11 pm
Hi Dieter
Those displays look good, take up less height
What was the price for the one you have
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 11, 2016, 07:38:00 pm
Hi Dieter
Those displays look good, take up less height
What was the price for the one you have
Thanks Dave
Price 22 Euro
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 11, 2016, 08:20:29 pm
OK... I'm going to need some help!  I attached 5V from my bench supply...

The unit draws only 220mA and it appears the low voltage side works...  (with no antenna attached) I have DS3 solid green, DS4 solid red and DS2 flashing green.

On the PWR pin of the OCXO I have 5V and nothing is getting warm

I have 5v on the middle and bottom pin of U1, I have 3v3 on the bottom pin of U7

On the U4? the daughterboard regulator I have +5V at both ends

What do you think? PTN04050CAS knackered?

I actually de-soldered the PTN04050CAS module and I can see that there is a 1.349k R between pin 1 and pin 3.... and doing the calculation this is meant to take 5V to exactly 12V.
This part is expensive approx US$20 but it is a good one... capable of delivering 12W... need to consider options and talk to seller :(
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: grumpydoc on March 11, 2016, 10:46:54 pm
I bought a couple of the symmetricom units to play with.

The ones I received look like the same batch that's going around right down to the mineral oil or whatever.

One looks OK, as seems common the other is missing the antenna connector but I haven't spotted any other damage (yet).

Has anyone any tips as to replacing the connector  - it looks to be quite a crowded area of the board. I'd rather replace the connector than solder a coax.

Also has anyone traced out the ribbon cable connector?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 11, 2016, 10:50:44 pm
Hi NivagSwerdna , were are you in the uk?

read this post from Macbeth on the 1st page,
Dave



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Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)

« Reply #15 on: December 13, 2015, 10:40:48 AM »


Quote

 

The Symmetricom and the Trimble versions of these should run at >5V-5.5V with a 2A supply no problem, PSU lead losses accounted for. Don't go too much over 5V as the supply is directly sent (minus a diode drop) to the external antenna, which are usually 3-5V.

The Symmetricom has a 12V OCXO and uses a TI PTN4050C boost converter while I understand the Trimble uses a 5V OCXO so doesn't need this.

My Symmetricom boost converter was DOA, as was the missing MCX antenna socket and the broken MACT switch.

The seller gave me the runaround and eventually pretended to send me a replacement board out and try and get me to "wait for it" one week after the ebay dispute timeout period. Of course with my simple notification that I would involve ebay he refunded me at the 11th hour.

I'm now using a cheap XL6009 instead. There are some other issues with starting this Symmetricom board with less than 1.7A too...


« Last Edit: December 13, 2015, 10:43:09 AM by Macbeth »

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on March 12, 2016, 12:09:30 am
Has anyone any tips as to replacing the connector  - it looks to be quite a crowded area of the board. I'd rather replace the connector than solder a coax.

Also has anyone traced out the ribbon cable connector?
I replaced the connector with one I salvaged from an old scrap board. I just kept the curly lead away and isolated all around with kapton tape then cleaned up the area, laid down some leaded solder with my iron, flux, and used the hot air to solder the salvage connector in place.

Now I did trace out most of the ribbon cable, which includes an extra com port (binary, ToD I think), but for the life of me I can't find my notes!  :palm:
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 12, 2016, 09:07:04 am
Hi, have a soldered IPEX socket, is very small !!
Dieter
(http://)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 12, 2016, 10:16:45 am
Hi NivagSwerdna , were are you in the uk?
I'll tell you once I've fixed it and the GPS Survey completes.  ;)

I'm now using a cheap XL6009 instead. There are some other issues with starting this Symmetricom board with less than 1.7A too...
I'll fire it up on the bench supply if I have time over the weekend. I might try an XL6009 module but it's nothing like the original which seems to be way more complex and presumably has better ripple etc.  For .99p I guess it's worth a shot and as long as it is above the regulation of the internal OCXO ref maybe it will be OK.  Not very happy with that.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 12, 2016, 10:31:19 am
My Symmetricom boost converter was DOA
This seems like a huge co-incidence... too much of a co-incidence, there really isn't much to age on that module.  I wonder if the DC-DC converter fail is actually a symptom of a problem with the OCXO from too long without use or similar?  Maybe there is a lesson to be learned as to how to power these on for the first time?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on March 12, 2016, 10:35:48 am
Quote
This seems like a huge co-incidence... too much of a co-incidence, there really isn't much to age on that module.  I wonder if the DC-DC converter fail is actually a symptom of a problem with the OCXO from too long without use or similar?  Maybe there is a lesson to be learned as to how to power these on for the first time?

Or the seller or person before them toasted them by not knowing the required voltage and using a high voltage power supply when testing.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 12, 2016, 04:10:35 pm
Now I did trace out most of the ribbon cable, which includes an extra com port (binary, ToD I think), but for the life of me I can't find my notes!  :palm:

I've only just started that process!  But I don't think there is a second serial port output.  I'm pretty sure RX is received and is routed to two pins of the 232 converter but there is only 1 TX outbound; would happily be proved wrong.

I removed the ribbon connector and hopefully the attached image might help someone.

Many of the pins are routed to vias and on the bottom of the board there are several FETs so presumeably driver outputs?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on March 12, 2016, 04:14:03 pm
Quote
This seems like a huge co-incidence... too much of a co-incidence, there really isn't much to age on that module.  I wonder if the DC-DC converter fail is actually a symptom of a problem with the OCXO from too long without use or similar?  Maybe there is a lesson to be learned as to how to power these on for the first time?

Or the seller or person before them toasted them by not knowing the required voltage and using a high voltage power supply when testing.

Hi

... or ... The piece of gear these originally were used in had a bulk switcher that tended to fail with a high output voltage. I've seen that both in the field and on shop floors. In most cases there are an amazingly large stream of returned parts before the problem is tracked down.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: grumpydoc on March 12, 2016, 09:12:10 pm
One looks OK, as seems common the other is missing the antenna connector but I haven't spotted any other damage (yet).
Ah, rats - C1 partially ripped from the board and flapping in the breeze, taking the vias with it on one board. the other looks like it might be OK if I remove it and superglue the tracks (and the cap) back to the board.

Previously if tracks have lifted I have had some luck with superglue - what does everyone else use, is there anything better?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on March 12, 2016, 11:02:15 pm
Has anyone had any luck in determining if there is the capability to read the data from the receiver in NMEA format. I saw this nice Arduino library, but no luck getting it to return any data. So far my only luck has been in receiving data using the commands at the start of the thread via the RS232.

http://arduiniana.org/libraries/tinygpsplus/ (http://arduiniana.org/libraries/tinygpsplus/)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: hs3 on March 12, 2016, 11:08:59 pm
OK... I'm going to need some help!  I attached 5V from my bench supply...

The unit draws only 220mA and it appears the low voltage side works...  (with no antenna attached) I have DS3 solid green, DS4 solid red and DS2 flashing green.

What do you think? PTN04050CAS knackered?


What kind power supply did you use when you tried to power it up? Did you try with any higher voltage?

I didn't have luck powering it up with 5V when I tested. It seems to have quite high inrush current at lower voltages.

Here you can see couple measurements I made with my unit:
https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg849591/#msg849591 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg849591/#msg849591)

Was the DC/DC converter making any sound when you tried it? In my case it had this whining sound when it didn't start up with lower voltage.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on March 12, 2016, 11:50:29 pm
I found that using my DP832 with 5-5.5v and winding it up to even 3A it wouldn't start. It would clamp the volts to ~3V and whistle. I determined the TI DC/DC converter was faulty and replaced with an ebay XL6009 after finding the TI part on AliExpress but the seller being a charlatan.

Strangely I can't power it up with the DP832 even at 5V 3A, but using any other PSU I have no problem, 5V @ 1.7A seems to be needed to start it. It settles down very quickly so it is a high inrush current.

Maybe my DP832 is faulty?  :-// Works great with everything else though. All my other PSU's go into the same whistling and 3V if powered with less than 1.6A.

Of course substituting the XL6009 muddies the waters.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 13, 2016, 12:19:27 am
What kind power supply did you use when you tried to power it up? Did you try with any higher voltage?
Benchtop TTi EL302RD Dual Supply.  5V limit to 2A
Was the DC/DC converter making any sound when you tried it? In my case it had this whining sound when it didn't start up with lower voltage.
Initially there was some whine but it was short lived and then settled to 150mA or so at 5V and 12V converter now seems to be straight through.
The 5V side seems to work OK.  Attached PC to the RX/TX/GND and can talk to the device.  Seems it used to hang out on top of a block of flats in down town Yokohama, Japan.
Next step is +12V to what was pin 4 of the converter and I also need to solder on a antenna connector to J2
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on March 13, 2016, 12:35:38 am
Initially there was some whine but it was short lived and then settled to 150mA or so at 5V and 12V converter now seems to be straight through.
The 5V side seems to work OK.  Attached PC to the RX/TX/GND and can talk to the device.  Seems it used to hang out on top of a block of flats in down town Yokohama, Japan.
Next step is +12V to what was pin 4 of the converter and I also need to solder on a antenna connector to J2
Yep, sounds familiar. I had it running off +5 and +12 from the DP832 no problem when the onboard TI boost module failed and I removed it. I also found the antenna voltage is whatever you power it with minus a typical 0.6 diode drop. So 5V - 5.5V is what you want considering a typical GPS antenna is 3.3V-5V rated.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: hs3 on March 13, 2016, 12:41:12 am
Strangely I can't power it up with the DP832 even at 5V 3A, but using any other PSU I have no problem, 5V @ 1.7A seems to be needed to start it. It settles down very quickly so it is a high inrush current.

Maybe my DP832 is faulty?  :-// Works great with everything else though. All my other PSU's go into the same whistling and 3V if powered with less than 1.6A.
It seems your experiences with DP832 match quite closely with my experiences with DP832 and this Symmetricom unit.

Maybe the DP832 current limiting kicks in quicker than the other supplies? In those scope captures there were spikes up to 8A when the converter tries to start.

I believe I have seen it mentioned somewhere that the correct voltage for the Trimble version would be about 6V. So could be similar for this Symmetricom version. So maybe 5V is just too much below the intended supply voltage for these.

What kind power supply did you use when you tried to power it up? Did you try with any higher voltage?
Benchtop TTi EL302RD Dual Supply.  5V limit to 2A
I think I have EL302D somewhere too. Maybe I should try with that too sometime later to have another data point.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: hs3 on March 13, 2016, 12:45:23 am
I also found the antenna voltage is whatever you power it with minus a typical 0.6 diode drop. So 5V - 5.5V is what you want considering a typical GPS antenna is 3.3V-5V rated.
One possibility is that the antennas used in the original application with these have used higher supply voltages than 5V too so these may not be the best fit with the typical low voltage GPS antennas that way.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on March 13, 2016, 01:37:06 am
It seems your experiences with DP832 match quite closely with my experiences with DP832 and this Symmetricom unit.

Maybe the DP832 current limiting kicks in quicker than the other supplies? In those scope captures there were spikes up to 8A when the converter tries to start.

I believe I have seen it mentioned somewhere that the correct voltage for the Trimble version would be about 6V. So could be similar for this Symmetricom version. So maybe 5V is just too much below the intended supply voltage for these.
Oh, believe me, I tried starting my board with 6V and limiting the amps and raising them only to find the DP832 clamping down at ~3V. Even dialling in 12V supply didn't help, the DP832 only supplied ~3V and the TI boost module would be ringing. I measured the VIN at the board with a DMM and sure enough it was clamped low no matter what you set the DP832 at.

That was with the TI module. Remove it and power with seperate 5V and 12V from the DP832 and it works great. But I switched the TI module for a cheap XL6009 module and found the same clamping the voltage low and oscillating when powering with 5-6V and 3.2A on the DP832.

Using my HP 6632B and my cheap ass Tenma PSU's I observed the same 3V clamping behaviour if powered with less than 1.6A CC, even when winding the current limit up to 5A.

I found starting with >=1.7A @ 5V it works just fine. Just not with any V or A on the DP832  :palm:
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: hs3 on March 13, 2016, 09:57:40 am
Oh, believe me, I tried starting my board with 6V and limiting the amps and raising them only to find the DP832 clamping down at ~3V. Even dialling in 12V supply didn't help, the DP832 only supplied ~3V and the TI boost module would be ringing. I measured the VIN at the board with a DMM and sure enough it was clamped low no matter what you set the DP832 at.

I believe :)

My comment about maybe needing more than 5V was intended more generally about these modules as in some cases I'm not sure if much higher than 5V supply has been used. Maybe it has but it haven't been clear to me.

But I think the additional details you provided how it behaved in your case are useful.

Quote from: Macbeth
That was with the TI module. Remove it and power with seperate 5V and 12V from the DP832 and it works great. But I switched the TI module for a cheap XL6009 module and found the same clamping the voltage low and oscillating when powering with 5-6V and 3.2A on the DP832.

Using my HP 6632B and my cheap ass Tenma PSU's I observed the same 3V clamping behaviour if powered with less than 1.6A CC, even when winding the current limit up to 5A.

I found starting with >=1.7A @ 5V it works just fine. Just not with any V or A on the DP832  :palm:
Ah so the XL6009 solution isn't working with the DP832 at all?

I haven't tested with the XL6009 so can't say much about it but I suppose that if it is a challenging load with the original TI converter then with the XL6009 it might be too.

Also regarding DP832 I think I have seen it mentioned in other places that it has been quicker to limit current than some other supplies even if the average current is not yet close to the current limits. So your DP832 may not be behaving differently than other DP832 units. But any other opinions/comments on this are welcome.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on March 13, 2016, 10:24:02 am
GPS- Display working  :) :) :) :) :)

Is there a link you can share to the project.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 13, 2016, 10:27:23 am
Making some progress... Hot air-ed a connector for GPS Antenna back on. 

Now applying 5V to top of F1 and 12V to what was output of DC-DC converter.

EL302RD Supply now proving 5V @ 230mA and 12V @ 180mA after approx 30 mins

It took a long time for the GPS to do anything but eventually it got an approx location and then after an age it worked out the time; probably not unsurprising due to the ephemeris data being at least 4 years out of date.  It seems to be trying to survey but is having trouble tracking enough satellites.

However, it does not look like I'm all systems go yet..

UCCM-P > ALARm:HARDware?
0.5Hz,Internal Reference
Command Complete

I seem to have a hardware alarm, only time will tell on that one.
 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on March 13, 2016, 11:08:04 am
Ah so the XL6009 solution isn't working with the DP832 at all?
No, it won't work at all. The same behavior as the original TI module (which eventually expired). I do wonder if the TI would have worked with my other PSUs? Too late to test that now...
Quote
Also regarding DP832 I think I have seen it mentioned in other places that it has been quicker to limit current than some other supplies even if the average current is not yet close to the current limits. So your DP832 may not be behaving differently than other DP832 units. But any other opinions/comments on this are welcome.
Yes kind of strange. Even though the GPSDO only needs <1.7A to run it does have a 10A fuse fitted on board. You do observe up to 8 amp startup spike!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 13, 2016, 12:11:27 pm
I see 500mA at 12V which declines to around 200mA as the OCXO warms up.  That's 6W at start-up, I don't see huge demand above that.

I guess if the onboard TI regulator is dead it makes sense to supply 12V regulated and step-down to 5V  if you have 12V available.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 13, 2016, 12:28:29 pm
By way of keeping myself amused as it does a site survey I have noticed that...

UCCM-P > TIME:STRing?
2016/03/13 12:26:34
Command Complete
UCCM-P >


FWIW Which is 17 seconds ahead of UTC.  So this time is true GPS time and has not been adjusted for the 17 seconds required to make it match wall clock time.  A trap for young players perhaps?   :D
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on March 13, 2016, 12:43:50 pm
I wonder if it is going to correct that:

While most clocks derive their time from Coordinated Universal Time (UTC), the atomic clocks on the satellites are set to GPS time (GPST; see the page of United States Naval Observatory). The difference is that GPS time is not corrected to match the rotation of the Earth, so it does not contain leap seconds or other corrections that are periodically added to UTC. GPS time was set to match UTC in 1980, but has since diverged. The lack of corrections means that GPS time remains at a constant offset with International Atomic Time (TAI) (TAI – GPS = 19 seconds). Periodic corrections are performed to the on-board clocks to keep them synchronized with ground clocks.

The GPS navigation message includes the difference between GPS time and UTC. As of July 2015, GPS time is 17 seconds ahead of UTC because of the leap second added to UTC June 30, 2015. Receivers subtract this offset from GPS time to calculate UTC and specific timezone values. New GPS units may not show the correct UTC time until after receiving the UTC offset message. The GPS-UTC offset field can accommodate 255 leap seconds (eight bits).


https://confluence.qps.nl/display/KBE/UTC+to+GPS+Time+Correction
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on March 13, 2016, 03:10:05 pm
By way of keeping myself amused as it does a site survey I have noticed that...

UCCM-P > TIME:STRing?
2016/03/13 12:26:34
Command Complete
UCCM-P >


FWIW Which is 17 seconds ahead of UTC.  So this time is true GPS time and has not been adjusted for the 17 seconds required to make it match wall clock time.  A trap for young players perhaps?   :D

Hi

UTC time has leap seconds in it. GPS time does not have leap seconds. If you have a system (like CDMA) that wants to sync up the codes on every other second ... dropping a second now and then is not a good thing. It is far more common to find systems that run on GPS time than UTC.

Bob

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 13, 2016, 03:36:32 pm
GPS- Display working  :) :) :) :) :)

Is there a link you can share to the project.
Here everything is already described.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 13, 2016, 04:39:58 pm
Well it eventually finished its site survey and is now in Position Hold but I don't still don't have any 10Mhz output

UCCM-P > SYSTem:STATus?
-------------------------------------------------------------------------------
090-03861-03   serial number W5609120195   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     9             FFOM     3
                                              UCCM-P Status[ALARM]

>> GPS: [phase: -2.27e-04]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 5 ____   Not Tracking: 8 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      16:38:39     13 MAR 2016
 14  43 295   32     2   8 113                GPS      Synchronized to UTC
 17   8  34   34     6  14  74                ANT DLY  +0.000E+00
 19  30  50   39    10   5 255                Position ________________________
 22   7 322   31    12  85  40                MODE     Hold
 32  -- ---   --    15   8 172
                    24  55 119                LAT      N  51:**:**.***
                    25  54 250                LON      W   0:**:**.***
                    29   6 191                HGT               +11.90 m  (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------
Alarms:  [0200] 0.5Hz Internal Reference
Command Complete
UCCM-P >


Looks that the "[0200] 0.5Hz Internal Reference" alarm suggests something is broken.   |O
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: gm8bjf on March 13, 2016, 06:22:21 pm
Hi,

I am new to this group and have found the posts very useful, - thanks!. I have just got a Symmetricom GPSDO from a UK supplier on Ebay. It arrived quickly and was in clean (no oil!) condition. A couple of caps were missing or loose but sorted that. Checking the log, it had come from Japan originally. I have been using it with the PUTTY terminal emulator to talk to it, but I have a copy of GPSCon for my Z3801. So far I have had no luck getting GPSCon to talk to the UCCM. Admittedly I have an early version of GPSCon ( Version 1.036 June 2004) but it seems to me as if it should work as they both use SCPI . Has anybody had experience of this ??

Brian.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on March 13, 2016, 09:04:09 pm
Quote

Looks that the "[0200] 0.5Hz Internal Reference" alarm suggests something is broken.   |O

You could try toggling through the following (no particular order) and see what happens. Unlikely that any of the settings write to memory upon power off and I believe the default is active so think your hunch about the internal reference is correct. Problem is trying to diagnose it is difficult as the message is so cryptic. Could be something as simple as a cold solder joint.

OUTPut:ACTive:ENABle
OUTPut:ACTive:DISable
OUTPut:INACTive
OUTPut:INACTive?
OUTPut:STATe?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 13, 2016, 09:16:15 pm
Problem is trying to diagnose it is difficult as the message is so cryptic.
Thanks for the support.  Yeap I'm confused.  Internal to?  The FPGA?  I'm wondering about the components down the edge... L20 was off when I got it.... but I can't see anything obviously out of place.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on March 14, 2016, 01:14:39 am
Problem is trying to diagnose it is difficult as the message is so cryptic.
Thanks for the support.  Yeap I'm confused.  Internal to?  The FPGA?  I'm wondering about the components down the edge... L20 was off when I got it.... but I can't see anything obviously out of place.

Hi

The message indicates that there is an error in generating the "every other second sync pulse". That pulse is generated off of the GPS time message and the selection process is run through the FPGA divider off of the 10 MHz oscillator. When the MCU checks the flag of "sent the pulse" against the MCU clock, that flag did not toggle as expected.

So, now you know *exactly* what the message means. You are no closer at all to fixing the problem.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on March 14, 2016, 01:58:23 am
GPS- Display working  :) :) :) :) :)

Is there a link you can share to the project.
Here everything is already described.

Ok, think I found it.
 
http://www.f4ctz.fr/?lang=en (http://www.f4ctz.fr/?lang=en)

If I understand what others have/are doing they are taking the TX off the GPC receiver circuitry, not the RS232 header circuitry and it outputs a data stream in NMEA format so the above project can read, decipher and display on the LCD?

The reason I ask is there is a  number of Arduino libraries that can read/interpret NMEA data streams.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on March 14, 2016, 02:11:36 am
GPS- Display working  :) :) :) :) :)

Is there a link you can share to the project.
Here everything is already described.

Ok, think I found it.
 
http://www.f4ctz.fr/?lang=en (http://www.f4ctz.fr/?lang=en)

If I understand what others have/are doing they are taking the TX off the GPC receiver circuitry, not the RS232 header circuitry and it outputs a data stream in NMEA format so the above project can read, decipher and display on the LCD?

The reason I ask is there is a  number of Arduino libraries that can read/interpret NMEA data streams.

Hi

The "good stuff" is not in standard NMEA strings. It's in NMEA format proprietary messages or in other even less easy to interpret strings. .

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 14, 2016, 08:10:13 am
The message indicates that there is an error in generating the "every other second sync pulse". That pulse is generated off of the GPS time message and the selection process is run through the FPGA divider off of the 10 MHz oscillator. When the MCU checks the flag of "sent the pulse" against the MCU clock, that flag did not toggle as expected.
:)

Well I know the GPS part is working since I can see tracking etc and it did a survey to hold.  I haven't watched the GPS messages as these aren't that interesting to me but perhaps I should look at the initialisation sequence.

I guess I don't know the OCXO is generating 10MHz, I can check that.  I did see a 0008 10MHz alarm once but it was quickly replaced with 0.5Hz alarm. 

Otherwise looks like the FPGA was damaged when the DC-DC converter died?

I think I'll just consider this as a scrap recovery victim and get another board.   8)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 14, 2016, 08:49:31 am
Have you got a scope or counter and go on the ocx
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 14, 2016, 09:14:17 am
Have you got a scope or counter and go on the ocx
Yeap. Got both of those.  When I'm next playing with this I will give it a go (really should be doing something more productive like real work!). 
However, I have checked OCXO power previously and got +12V so if it is crook (not oscillating) then I'm up a gum tree without a paddle as that wouldn't be worth economic replacement.  I'd have to chuck it down the dunny and get another.  With a bit of luck get another board, and she'll be apples.  :)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 14, 2016, 09:53:41 am
Did you tell the seller that it was not working and you wanted a replacement or refund,I did when mine was not working and sent photos of the damage and he told me he
Had sent another one out but nothing so I asked eBay to get involved and we gave more time, he contacted me and asked  me to close the claim as he had sent one,so I did not
Nothing came in the post and on the day eBay gave to see
If it had been closed, I got a nice email from paypay saying
That I had been refunded, the one he claimed  to of sent has never arrived ,get you're claim in with eBay,
Its crazy how much time we have spent on these,
Good job we were not paying some one to fix it
We would be broke,
Mine is pluged in to my Kenwood TS-2000 Radio :-+
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 14, 2016, 06:44:28 pm
Did you tell the seller that it was not working and you wanted a replacement or refund...
That's a work in progress.

Has anyone logged the GPS receiver output?  Which messages do you get?  (Some will be regular e.g. Position/Day etc, some will be much less regular e.g. Ephemeris changes). 
Also on start-up does the unit send messages to the receiver or does it persist its state?  Maybe it's forgotten it needs to send something (due to my use  of an inappropriate command perhaps?)

Thanks
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on March 14, 2016, 07:17:21 pm
Did you tell the seller that it was not working and you wanted a replacement or refund...
That's a work in progress.

Has anyone logged the GPS receiver output?  Which messages do you get?  (Some will be regular e.g. Position/Day etc, some will be much less regular e.g. Ephemeris changes). 
Also on start-up does the unit send messages to the receiver or does it persist its state?  Maybe it's forgotten it needs to send something (due to my use  of an inappropriate command perhaps?)

Thanks

Hi

There is always some sort of dialog that enables / disables specific repeated messages. Depending on how this is set, you will get different messages out of any GPS module or GPSDO.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 15, 2016, 01:20:28 am
There is always some sort of dialog that enables / disables specific repeated messages. Depending on how this is set, you will get different messages out of any GPS module or GPSDO.
Yes. That's why I asked if anyone had recorded it in this case.
The Furuno has some state that is retained between power cycles including estimated position and ephemeris.
Other behaviour is configured by an initial exchange of messages at power up.  I was interested in that exchange from a unit that does not exhibit the 0.5Hz Alarm condition.
$PFEC ?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on March 15, 2016, 01:45:24 am
There is always some sort of dialog that enables / disables specific repeated messages. Depending on how this is set, you will get different messages out of any GPS module or GPSDO.
Yes. That's why I asked if anyone had recorded it in this case.
The Furuno has some state that is retained between power cycles including estimated position and ephemeris.
Other behaviour is configured by an initial exchange of messages at power up.  I was interested in that exchange from a unit that does not exhibit the 0.5Hz Alarm condition.
$PFEC ?

Hi

If you cut into the connections on the RX and TX on the GPS module, you can do a lot of things. The normal "timing info" port does not allow you to do variable NMEA.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Pat Pending on March 15, 2016, 07:52:33 am
My oily Symmetricom UCCM board arrived today with C1 hanging in the air by one
ripped trace and missing a boost capacitor on the 232 interface.

My R53 is cracked in two, (resembles a mini pacman) but there is no markings of any sort to suggest its value.
I'd appreciate if someone could measure the value R53, thanks in advance.

I've attached a pic (not my brd) showing the general location.


Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on March 15, 2016, 03:40:51 pm
Measured in circuit, 22 ohms. Seems small.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: gm8bjf on March 15, 2016, 10:39:29 pm
Thanks for the post, I'm contemplating buying one of these modules. What is the main connector pinout?

The ribbon connector pinout is given for the Trimble UCCM unit at:

https://xdevs.com/fix/rb_lpfrs/

If you scroll through this you will find the second part of the posting is deals with the Trimble equivalent UCCM unit. As they are mechanically  identical in terms of the connectors and fixings I assume the connectors are the same. The units appear to have been designed to the same spec so I think this is a reasonable assumption. The reporting software seems to produce identical responses.

73s

Brian.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 15, 2016, 11:55:19 pm
The units appear to have been designed to the same spec so I think this is a reasonable assumption.
Hm.... I don't think that is correct see my earlier rather insubstantial ribbon pinout.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 16, 2016, 12:05:19 am
If you cut into the connections on the RX and TX on the GPS module, you can do a lot of things. The normal "timing info" port does not allow you to do variable NMEA.
No need to cut anything.  You can just listen in pin 3 TX, pin 4 RX and pin 5 1PPS.

From GPSDO to GPS I have seen examples of these commands (not in this order or frequency)...

$PFEC,GPint,GGA01
$PFEC,GPint,GSA01
$PFEC,GPint,GSV00
$PFEC,GPint,VTG00
$PFEC,GPint,ZDA00
$PFEC,GPint,acc00
$PFEC,GPint,anc00
$PFEC,GPint,anc00,acc00
$PFEC,GPint,rrm01
$PFEC,GPint,tps01
$PFEC,GPint,tst00
$PFEC,GPrrq
$PFEC,GPrrs,1,100,1
$PFEC,GPset,M05
$PFEC,GPset,U00000000
$PFEC,GPset,Z1
$PFEC,GPset,t-000080
$PFEC,GPsrq


on the output side I see...

$GPGGA
$GPGSV
various
$PFEC
e.g.
$PFEC,GPacc,XXXXXX0XXXXXXXXXXXX00XXXXX0XXXXX
$PFEC,GPacc,XXXXXXXXXXXXXXXXXXX00XXXXX0XXXXX
$PFEC,GPanc,800106000000,00000000002000000002200000200000
$PFEC,GPanc,800106000000,00000020002220000002200000200000
$PFEC,GPanc,800106000000,00000020002222200002200000200000
$PFEC,GPanc,800106000000,00000020002222222002200000200000
$PFEC,GPrrm,2,2,00,00,00,00,+000,+00
$PFEC,GPtps,160315224627,2,0,1,000000000000,00,00,000000000000,1888,254787
$PFEC,GPtst,0,4850266005,1,C


Steady state (in survey mode at least) is for 1 Hz output looking something like...

$PFEC,GPtps,160315233257,1,0,1,150701000000,00,17,160315231107,1888,257594
$PFEC,GPrrm,2,2,00,00,00,00,+000,+00
$GPGGA,233258,****.3935,N,*****.4444,W,0,00,00.00,000005.1,M,0046.9,M,,
$GPGSA,A,1,,,,,,,,,,,,,00.00,00.00,00.00


I doubt anyone will find that very interesting.   :)

The protocol spec is here http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Furuno/Furuno_GT8031_Protocol_Specification_Rev1.pdf (http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Furuno/Furuno_GT8031_Protocol_Specification_Rev1.pdf)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 16, 2016, 12:13:15 am
Time and PPS Status

$PFEC,GPtps,160315233257,1,0,1,150701000000,00,17,160315231107,1888,257594

   Note:
The date/time based on the RTC is output after the GT-8031 is turned on until it starts
tracking a satellite.
 GPS Time is output after the GT-8031 starts tracking a satellite until it collects a UTC
parameter (including UTC offset) in the cold start condition.
 UTC is output after the GT-8031 collects a UTC parameter while tracking a satellite. 1PPS
is also output under this condition.

RAIM Status
$PFEC,GPrrm,2,2,00,00,00,00,+000,+00

Position and Time (UTC) Standard NMEA
$GPGGA,233258,****.3935,N,*****.4444,W,0,00,00.00,000005.1,M,0046.9,M,,

Positioning and Status PDOP et al.
$GPGSA,A,1,,,,,,,,,,,,,00.00,00.00,00.00

Of course none of this is really useful to most people since what we really care about is the FGOM for the timing loop and that comes out of the other serial port.  But in my case this at least proves the GPS module is behaving correctly and I see a nice 1PPS on Pin5, I also measured the OCXO and it is giving a stable 10MHz approx so I am no nearer knowing where the 0.5Hz alarm is coming from.  (But it was fun having a probe)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on March 16, 2016, 04:37:13 am
Measured in circuit, 22 ohms. Seems small.
Checked some others, and that seems correct.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 16, 2016, 08:57:55 am
I would bet there's a way to apply battery to the board and avoid all this, but I don't know what it is yet.
The Fununo GT-8031 will accept a 3v3 backup battery across Pins 7 (BAT) and Pin 8 (GND) but according to the spec it has a typical 174uA current draw.  I think 174uA is enough to deplete a CR2032 in just a couple of months.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 16, 2016, 09:31:40 am
Hi I have tried a battery to see if it stopped the unit from doing a survey after power up,
It did not change this.
Thanks Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 16, 2016, 06:31:59 pm
Hi I have tried a battery to see if it stopped the unit from doing a survey after power up,
It did not change this.
Thanks Dave
Hm... OK.  I guess that is to be expected.  Survey mode is the default and I also see it sends a Z1 to the receiver.  I wonder if sending GPS Position helps? 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 16, 2016, 06:34:08 pm
...So, now you know *exactly* what the message means. You are no closer at all to fixing the problem....
Bob

I have now got...

Alarms:  [02A0] 0.5Hz Internal Reference EFC

UCCM-P > ALARm:HARDware?
EFC Limit Exceeded,0.5Hz,Internal Reference
Command Complete


Maybe that one can be a bit more specific?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Pat Pending on March 16, 2016, 08:44:24 pm
Measured in circuit, 22 ohms. Seems small.
Checked some others, and that seems correct.
Thanks Vgkid
I guess the low resistance value is to control reflections and waveshape seen at the end of this trace.
After some repairs getting enough power to the board looks like a big issue.
It squeals for a while until the OCXO warms up. That was at 5V5 measured between fuse and ground.
I could adjust it higher but there's a linear regulator producing 3V3 from that and I didn't want to overdo it. Just how high can Vin be ?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on March 16, 2016, 08:47:23 pm
Dont go over 6. It will shut off, both of mine squel.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 17, 2016, 12:02:53 am
Hey!  I think I might have found something!  I don't seem to have a C94
Please can someone suggest a value for this component.

I can see from https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg846858/#msg846858 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg846858/#msg846858) that they do have a C94.  I notice that their board is missing C122 which I do have.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Pat Pending on March 17, 2016, 12:41:58 am
Hey!  I think I might have found something!  I don't seem to have a C94
Please can someone suggest a value for this component.

c94 (like C73 closeby) go to the same internal power planes, it's a decoupling cap.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 17, 2016, 08:06:15 am
c94 (like C73 closeby) go to the same internal power planes, it's a decoupling cap.
Thanks!  Might not be the explanation of my 0.5Hz Alarm then but I'll put something there anyway and see.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 18, 2016, 02:31:14 pm
OK... I'm on to unit#2...

Hooked up to my TTi EL302RD supply and set to 5V 2A... when I turn it on I get... 3.27v and 1.25A with the CC lit...  on the output of the squealing TI boost converter I get 9V.

What's all that about then?  Sounds like I've fallen into a trap for young players?

After a while the squealing dies down and the OCXO is nicely warm and the power supply goes to 5V 770mA and CC goes out.

Fingers crossed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on March 18, 2016, 02:56:21 pm
Sounds like what both of mine do.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 18, 2016, 03:01:08 pm
Sounds like what both of mine do.
Do you know why my Power supply goes into CC mode?  It should be able to deliver up to 2A @ 5V?  Is it something to do with inductive loads?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on March 18, 2016, 03:55:59 pm
Can your psu go above 2A, i think mine might take about 2.2A
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 18, 2016, 05:16:02 pm
Can your psu go above 2A, i think mine might take about 2.2A
"The EL302RD has two independent and isolated outputs each with a 0
to 30V, 0 to 2A capability and its own on-off switch. The outputs can
be wired in either series or parallel to provide voltages up to 60 volts
or currents up to 4 amps."

It's rated as dual 0-2A 0-30V.  I might try them in parallel and see what happens... it appears you can do that and get up to 4A.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: hs3 on March 18, 2016, 09:44:50 pm
Hooked up to my TTi EL302RD supply and set to 5V 2A... when I turn it on I get... 3.27v and 1.25A with the CC lit...
I have just tested with EL302D. Set to 6V and 2A. I get the same behavior that you described above. I also tried paralleling the outputs but no improvement.

This is with the same Symmetricom unit that works with Rigol DP832 set to 6V 3A as discussed couple pages earlier.

So it doesn't seem to be suitable load for the EL302D supplies.

There is probably a reason why the fuse at the input is 10A on the Symmetricom module.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 19, 2016, 01:59:08 am
Interesting.

When I was powering from 2 supplies... 5V @ 250mA and 12V @ 500mA during warm up the total was around 7.25W or equiv of 1.45A @ 5V.
Even with inefficiency of the DC-DC converter that should be under 2A @ 5V.  I think the EL302RD just isn't oommpfy enough.

By the way...

UCCM-P > SYSTem:STATus?
-------------------------------------------------------------------------------
090-03861-03   serial number W560935175   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     2             FFOM     0
                                              UCCM-P Status[ACTIVE]

>> GPS: [phase:  1.77e-08]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 6 ____   Not Tracking: 4 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      01:57:23     19 MAR 2016
 10  29  52   42     1  51 274                GPS      Synchronized to UTC
 11  67 280   34     3  16 214                ANT DLY  +0.000E+00
 14  29  90   34     8  62 161                Position ________________________
 22  62 186   31    32  31  97                MODE     Hold
 27  31 143   35
 28  27 311   36                              LAT      N  51:**:**.***
                                              LON      W   0:**:**.***
                                              HGT               +10.90 m  (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------

Command Complete
UCCM-P >


We have lift off!  Just need to know how to route the LEDs to the front panel now and maybe do some serial interfacing for an LCD showing FFOM to front panel.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 19, 2016, 07:06:22 am
That's good news,was it your missing cap,
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 19, 2016, 12:38:08 pm
That's good news,was it your missing cap,
Dave
No.  I gave up on that unit and it is on its way back to China. 

I bought another and although that had one missing cap, it was easily fixed and working now.   

I think the original had some big issues, certainly wasted a huge amount of my time.

I'm now plotting what to do with the interface.  I'm tempted to add an Arduino based front-end to display FFOM etc on a front panel, but really I should do the LEDs first.

Does anyone actually know the meaning of the 5 LEDs on the board?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 19, 2016, 12:55:14 pm
Hi others have put some info on the LEDs on the 1page ,
I may fit 4 LEDs but 2 will tell you its good the green for lock
And the red for 1pps,

So you had to send the unit back to China, what was the cost of that ,has he given you a refund or do you have to wait for him to receive it
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 19, 2016, 06:37:02 pm
So you had to send the unit back to China, what was the cost of that ,has he given you a refund or do you have to wait for him to receive it
That's a work in progress.  Under Paypal/EBAY Buyer protection if item is "Not As Described" then Seller has to pay return postage and offer refund (although they might try and convince you otherwise).
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: grumpydoc on March 19, 2016, 06:47:32 pm
Hi yes you have a bad unit , fly seller will tell you he will send another one but he will not send,tell him you want a refund, open a case with ebay, he asked me to close the case I opened as he said  he had sent another one,
I did not close the case, and ebay refunded me from his account , and the replacement unit never did arrive ,
still I did get the broken one working, as I put on a new u25 inverter chip and caps
Dave
Looks like he does this regularly as he promised me a replacement and nothing has shown up. I wouldn't mind if he had actually sold them as "parts or repair". Looks like I will need to put it through ebay.

Now that I look carefully at the pictures C1 is loose in the sellers photos.

The bottom line, I suppose is, if you buy one of these, expect to have to do some repair work.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on March 19, 2016, 07:39:15 pm
Same here. He asks to send it back. Once you tell him the full cost of tracked and that he has to pay for it he's not happy, so will then pretend to ship a new one out to you. Don't waste your time. Better to just buy another one and then claim the older one as a dud on ebay and use it for repair parts, because you will definitely need them!  ::)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 19, 2016, 08:20:36 pm
Hi have you seen from a post on here there is a UK seller selling these for the same price, don't know if they are sent in the UK?
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on March 20, 2016, 09:06:19 am
GPS- Display working  :) :) :) :) :)

Is there a link you can share to the project.
Here everything is already described.

Ok, think I found it.
 
http://www.f4ctz.fr/?lang=en (http://www.f4ctz.fr/?lang=en)

If I understand what others have/are doing they are taking the TX off the GPC receiver circuitry, not the RS232 header circuitry and it outputs a data stream in NMEA format so the above project can read, decipher and display on the LCD?

The reason I ask is there is a  number of Arduino libraries that can read/interpret NMEA data streams.

Hi

The "good stuff" is not in standard NMEA strings. It's in NMEA format proprietary messages or in other even less easy to interpret strings. .

Bob
If you cut into the connections on the RX and TX on the GPS module, you can do a lot of things. The normal "timing info" port does not allow you to do variable NMEA.
No need to cut anything.  You can just listen in pin 3 TX, pin 4 RX and pin 5 1PPS.

From GPSDO to GPS I have seen examples of these commands (not in this order or frequency)...

$PFEC,GPint,GGA01
$PFEC,GPint,GSA01
$PFEC,GPint,GSV00
$PFEC,GPint,VTG00
$PFEC,GPint,ZDA00
$PFEC,GPint,acc00
$PFEC,GPint,anc00
$PFEC,GPint,anc00,acc00
$PFEC,GPint,rrm01
$PFEC,GPint,tps01
$PFEC,GPint,tst00
$PFEC,GPrrq
$PFEC,GPrrs,1,100,1
$PFEC,GPset,M05
$PFEC,GPset,U00000000
$PFEC,GPset,Z1
$PFEC,GPset,t-000080
$PFEC,GPsrq


on the output side I see...

$GPGGA
$GPGSV
various
$PFEC
e.g.
$PFEC,GPacc,XXXXXX0XXXXXXXXXXXX00XXXXX0XXXXX
$PFEC,GPacc,XXXXXXXXXXXXXXXXXXX00XXXXX0XXXXX
$PFEC,GPanc,800106000000,00000000002000000002200000200000
$PFEC,GPanc,800106000000,00000020002220000002200000200000
$PFEC,GPanc,800106000000,00000020002222200002200000200000
$PFEC,GPanc,800106000000,00000020002222222002200000200000
$PFEC,GPrrm,2,2,00,00,00,00,+000,+00
$PFEC,GPtps,160315224627,2,0,1,000000000000,00,00,000000000000,1888,254787
$PFEC,GPtst,0,4850266005,1,C


Steady state (in survey mode at least) is for 1 Hz output looking something like...

$PFEC,GPtps,160315233257,1,0,1,150701000000,00,17,160315231107,1888,257594
$PFEC,GPrrm,2,2,00,00,00,00,+000,+00
$GPGGA,233258,****.3935,N,*****.4444,W,0,00,00.00,000005.1,M,0046.9,M,,
$GPGSA,A,1,,,,,,,,,,,,,00.00,00.00,00.00


I doubt anyone will find that very interesting.   :)

The protocol spec is here http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Furuno/Furuno_GT8031_Protocol_Specification_Rev1.pdf (http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Furuno/Furuno_GT8031_Protocol_Specification_Rev1.pdf)


Monitoring the output of the GPS tx pin and it is returning similar data. Advantage of the output format vs the serial output is it would be easier to process using the comma delimiters. Goal is to output some of the useful data onto a LCD or OLED screen from a Arduino project. Similar to the other project that has been referenced.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 20, 2016, 10:26:40 am
Monitoring the output of the GPS tx pin and it is returning similar data. Advantage of the output format vs the serial output is it would be easier to process using the comma delimiters. Goal is to output some of the useful data onto a LCD or OLED screen from a Arduino project. Similar to the other project that has been referenced.
We should join forces.  The really interesting stuff is the SCPI ('skippy') on the main serial connection as that includes the FFOM and timing loop info.  The NMEA on the receiver will give you position and time, the position will be fixed for me so that isn't hugely interesting.  The time from the NMEA is always behind actual time, so if you are happy with a time that is 500mS late (and may or may not have been adjusted for GPS versus UTC) that might be OK, you can always use the PPS signal to adjust the edge back.
I haven't yet decided whether to use an Arduino clone (since they are so cheap) or to use a Raspberry Pi and just make it into an NTP server too.  I quite like the idea of these two since it could an open source solution and easily reproducible.  Haven't decided on a display yet... will probably go for a simple 16x2 LCD.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 20, 2016, 12:39:52 pm
Hi I talked to Dan about the led and it is a bug he thinks it may go off when the survey has Finnished
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 20, 2016, 02:34:09 pm
Hi I talked to Dan about the led and it is a bug he thinks it may go off when the survey has Finnished
Dave
OK, thanks
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: bseishen on March 20, 2016, 08:02:48 pm
Created a 3d printed mounting plate if anyone wants to use it. Its just a plate with standoffs. Uses m3 screws to hold the GPSDO down.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on March 21, 2016, 08:16:56 am
Monitoring the output of the GPS tx pin and it is returning similar data. Advantage of the output format vs the serial output is it would be easier to process using the comma delimiters. Goal is to output some of the useful data onto a LCD or OLED screen from a Arduino project. Similar to the other project that has been referenced.
We should join forces.  The really interesting stuff is the SCPI ('skippy') on the main serial connection as that includes the FFOM and timing loop info.  The NMEA on the receiver will give you position and time, the position will be fixed for me so that isn't hugely interesting.  The time from the NMEA is always behind actual time, so if you are happy with a time that is 500mS late (and may or may not have been adjusted for GPS versus UTC) that might be OK, you can always use the PPS signal to adjust the edge back.
I haven't yet decided whether to use an Arduino clone (since they are so cheap) or to use a Raspberry Pi and just make it into an NTP server too.  I quite like the idea of these two since it could an open source solution and easily reproducible.  Haven't decided on a display yet... will probably go for a simple 16x2 LCD.



I am the same, not very interested in the GPS coordinates, but want to know the phase and frequency differences, how many satellites, timing etc. I would like to use a OLED vs a LCD.

http://cyaninfinite.com/tutorials/interfacing-0-96-oled-display-with-arduino-uno (http://cyaninfinite.com/tutorials/interfacing-0-96-oled-display-with-arduino-uno)

There is a number of Arduino libraries that can interpret NMEA strings, shouldn't be too hard too implement to extract the data that I need. I am sure you have seen the pdf on the NMEA commands that the receiver should support. Was going to try later this weekend and see if I can successfully send the GPS the commands through the receiver and see what it returns. Should be able to get some of the timing information.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: gm8bjf on March 21, 2016, 03:56:44 pm
Hi have you seen from a post on here there is a UK seller selling these for the same price, don't know if they are sent in the UK?
Dave

I have had a couple from the UK seller. The first one was fine, just needed an SMD cap in the RS232 interface replacing. The second one has been more problematic and I am awaiting a replacement. The seller seems good and volunteered a replacement right away. The boards seem to come from the same source in the Far East as the second one I got had the "oilyness" and more loose/missing parts. However at the price they are not too bad. Mine both had their last loogged co-ordinates in Japan. I see on TaoBao.com they are about the equivalent of £16 !

Brian.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on March 21, 2016, 10:50:45 pm

Got a package from China today. Slammed some components on the PCB and did some first tests.

(http://members.home.nl/baltusg/UCCM%20readout1.jpg)

Not much to it, designed it with components from the stash. From left to right:
 - connector to LCD (two pins bigger than needed, but i had some flatcable with connector available)
 - pic 16F627A to read the UCCM and write to the LCD, specific xtal frequency to match the baudrates
 - DCDC regulator from 12V to 5V (customer specific version, but Fabrimex was very helpful).
 - RS232 level shifter (using the standard RX/TX header on the UCCM). Relay switches between pic and DB9.

(http://members.home.nl/baltusg/UCCM%20readout2.jpg)

This is the general idea; i am going to stack the PCBs. For testing the readout PCB is on top. I will swap later. The RS232 headers line up. Some resistors are just mounted temporary, as i need to change them later to adjust the brightness of the final LEDs.

(http://members.home.nl/baltusg/UCCM%20readout3.jpg)

It worked in one go  :-+ Note the software was written for a 16x2 display untill now. This is why the bottom half on the display is not initialized. This display is two times a 40x2 display, with separate enable lines.

The text is coming from the UCCM (no antenna connected). So reading and writing (i'm switching to 9600 baud) works. And writing to the LCD obviously works.

Now it is only a matter of software to read the various strings from the UCCM and writing them on the display. Got enough space  :P
This will take a while, not much time at the moment. And then putting it all in a nice enclosure.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on March 21, 2016, 11:45:12 pm
Nice job  :-+ .
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 22, 2016, 01:06:37 am
I see you have 4 LEDs.  Please can you show how/where you are attaching these.

Have you left the old SMD LEDs on the board?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on March 22, 2016, 06:44:43 am
Hi,

I see you have 4 LEDs.  Please can you show how/where you are attaching these.

Have you left the old SMD LEDs on the board?

Personally, I've unsoldered the leds and connect new ones on the frontplate:

https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-%28ocxo-furuno-receiver%29/msg823156/#msg823156 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-%28ocxo-furuno-receiver%29/msg823156/#msg823156)


Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 22, 2016, 08:10:10 am
Personally, I've unsoldered the leds and connect new ones on the frontplate:
Did you need 2 wires for each or do they have a common (ground?) on one side?
Thanks in advance
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on March 22, 2016, 08:30:57 am
Personally, I've unsoldered the leds and connect new ones on the frontplate:
Did you need 2 wires for each or do they have a common (ground?) on one side?
Thanks in advance


Hi didn't even checked, just soldered 2 wires for each (they are dual LEDs).


Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on March 22, 2016, 06:14:38 pm
in my case i'm not using the LEDs on the UCCM. One is power supply, one is showing 12V to XO (it is switchable) and the other two will be controlled by the pic. Current plan; one to indicate that the output is on and one in case of an alarm. Tbd.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 22, 2016, 09:04:04 pm
That look good ,good idea with the LEDs to test what one was what,
what op-amps did you use for your output board,
I am fitting a usb interface on mine,
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on March 22, 2016, 10:44:02 pm
That look good ,good idea with the LEDs to test what one was what,
what op-amps did you use for your output board,
I am fitting a usb interface on mine,
Dave
the op-amps are 4x AD811 buffer output amplifier
-->usb interface what a circuit ??
Dieter
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 22, 2016, 10:55:48 pm
Hi it was just a cheep £1 ftdi board from China
That has mini USB and I got a mini usb to std USB B panel mount lead I got 1for my Trimble as well
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: bingo600 on March 24, 2016, 06:30:03 pm
Hi Daniel
Yes please that would be brill,i wish I could do that,
Thanks Dave 2E0DMB

Here it is. Please tell me if it works, this way I can send the fix to the original author.


Cheers.
---
Daniel

Re:
https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg849732/#msg849732 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg849732/#msg849732)

Any change of getting the sourcecode , or at least a description of the differences against the below source 

Afficheur-GPS-V2.22-Source
http://www.f4ctz.fr/?page_id=692&aid=1282&sa=1 (http://www.f4ctz.fr/?page_id=692&aid=1282&sa=1)

I'm using AVR not PIC

/Bingo
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 24, 2016, 09:24:04 pm
FWIW... This is what I'm going to use... 

http://www.ebay.co.uk/itm/221831832114 (http://www.ebay.co.uk/itm/221831832114)  2.4" Touch Screen

http://www.ebay.co.uk/itm/291716131140 (http://www.ebay.co.uk/itm/272041591038)   Arduino Mega2560

The Mega has 4 UARTs, so I can do both sets of serial (SCPI in/out and GPS out) and provide USB out to a PC when required.

I'll let you know how it goes
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 24, 2016, 09:32:25 pm
Hi that should be good,
please let us know
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on March 24, 2016, 10:05:16 pm
Hi Daniel
Yes please that would be brill,i wish I could do that,
Thanks Dave 2E0DMB

Here it is. Please tell me if it works, this way I can send the fix to the original author.


Cheers.
---
Daniel

Re:
https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg849732/#msg849732 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg849732/#msg849732)

Any change of getting the sourcecode , or at least a description of the differences against the below source 

Afficheur-GPS-V2.22-Source
http://www.f4ctz.fr/?page_id=692&aid=1282&sa=1 (http://www.f4ctz.fr/?page_id=692&aid=1282&sa=1)

I'm using AVR not PIC

/Bingo
I sent the patch this week for the furuno support to F4CTZ, I think he will made it available soon (full source code or patch only, I don't know).

Cheers.
---
Daniel
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on March 27, 2016, 08:57:21 pm
All:

Pin 3 is referred as the GPX TX from other photos in the thread. Which is the RX pin in my edited photo. Is it 4?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on March 27, 2016, 09:42:33 pm
I think your numbering might be off.

I read it as

1 2
3 4
5 6
7 8
9 X

or the other way up (in your pic)

RD and TX are on the same row

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on March 27, 2016, 09:53:32 pm
Thanks for the help, yes the numbering is wrong . So in short my pin 4 in the picture is the RX(RD) pin.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: gm8bjf on March 28, 2016, 02:39:15 pm
Hi have you seen from a post on here there is a UK seller selling these for the same price, don't know if they are sent in the UK?
Dave
Hi Dave,
Just seen your post. The supplier I was referring to is here:

http://www.ebay.co.uk/itm/Used-SYMMETRICOM-UCCM-GPS-10MHz-Frequency-Time-Receiver-OCXO-/281950388728?hash=item41a58d81f8:g:Er8AAOSwv9hW (http://www.ebay.co.uk/itm/Used-SYMMETRICOM-UCCM-GPS-10MHz-Frequency-Time-Receiver-OCXO-/281950388728?hash=item41a58d81f8:g:Er8AAOSwv9hW)

They still seem to have some. There are three suppliers here in UK but I suspect they are aliases of the same shop. All are based in Salford. I have had three units from them and all have required various degrees of repair and cleaning. They are posted from the UK. Latest fault was one of the TI buck converter boards failing while in operation. The units seem to have originated from the far east and have have coordinates around Tokyo and Okoyama in Japan stored in them, same as the ones direct from China. The UK based supplies are actually cheaper than the Chinese ones and you don't have to wait 2-3 weeks! ;)
I have found the supplier easy to deal with. When one of my units was quite badly damaged they sent a replacement.

Brian GM8BJF
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 28, 2016, 02:52:47 pm
Hi Brian
Thanks for the info, it is good to know that they sent you a
Replacement unit, did they let you keep the old unit?
Thanks Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on March 28, 2016, 09:30:13 pm
Would it be better to buy this Symmetricom or the Trimble 65256 GPS OCXO from the same seller?

The Symmetricon is faster since it's available in the UK, the Trimble must come from the other side, the price it's about the same.

Any ideas?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on March 29, 2016, 08:12:18 am
The only thing about the Symmetricom is that when you do a power off on re-connect it will take 2hours to do a survey ,but the trimble remembers and saves its settings so when the trimble gets lock that's it going after mins not hours,
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on March 29, 2016, 08:49:46 am
davebb,

The GPSDO will be to put on a shelf over the bench, to plug the Frequency counter, and other stuff, so I don't see me to unplug it very often.
But I can always add some switch to change from +5VDC 3A, to battery pack to move it.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: gm8bjf on March 29, 2016, 11:21:52 am
Hi Brian
Thanks for the info, it is good to know that they sent you a
Replacement unit, did they let you keep the old unit?
Thanks Dave 2E0DMB

Hi Dave,

Yes they did, but its Buck inverter has now gone to the great scrapyard in the sky for no obvious reason! From messages on Ebay I have the impression they are Chinese sellers in the UK.

73s

Brian.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on March 29, 2016, 01:04:31 pm
Well, thinking more about this and going trough the parts recycle bin, I've found some GPS boards Navman Jupiter-T TU30-D405-005, WITH 10kHz and 1PPS outputs, so the only thing that is needed is one OCXO like the MV89 from Morion, and one circuit like the one from G3RUH < http://www.jrmiller.demon.co.uk/projects/ministd/frqstd0.htm (http://www.jrmiller.demon.co.uk/projects/ministd/frqstd0.htm) >.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on March 29, 2016, 06:04:20 pm
The only thing about the Symmetricom is that when you do a power off on re-connect it will take 2hours to do a survey ,but the trimble remembers and saves its settings so when the trimble gets lock that's it going after mins not hours,
Dave

I have the feeling it is sometimes quicker. But sometimes not so. I'm poking my position into the unit, maybe if i use a fixed GPS antenna (on the to-do list) that would really work. According to another manual (58503B unit) poking position and time/date should help to speed things up. I´ve tried it,  but did not find an improvement. But maybe that´s because the gps antenna is not a fixed one. If more people could try  :)

Unfortunately i won´t be able to easily load date/time with my acient pic solution. Could add an RTC chip but that also requires setting (and writing software to do so). Current status is that i have multiple reponse strings on the display and switching on a red LED in case the pll status is not saying PLL stabilized. The info is also on the display obviously, but a red LED will be much more visible.

When i get more time, i´ll continue with the button control for the output and it´s status LED and then some costmetics. It´s a slow process, i program in assembly (and i like it)  :palm:
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on April 01, 2016, 07:21:41 am
For those in the US who are interested in one of the Symmetricom GPSDO's there is a seller on ebay who has a few for 43.99 shipped. To find them you can search for "SYMMETRICOM UCCM", I have no relation to seller, but if they work it is a pretty decent price.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on April 02, 2016, 09:49:30 am
For those in the US who are interested in one of the Symmetricom GPSDO's there is a seller on ebay who has a few for 43.99 shipped. To find them you can search for "SYMMETRICOM UCCM", I have no relation to seller, but if they work it is a pretty decent price.

Searching with "SYMMETRICOM UCCM" on EBay doesn't bring anything up other than the seller from China. Do you have a EBAY listing number.

Cheers
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 02, 2016, 10:09:47 am
I traced out the LEDs so that I could work out what I need on the front-panel.

I'm still not exactly sure what they all do but it seems that ACT (DS3 Green) comes from the FPGA (as does the Green side of DS4), all other LEDs are controlled by the H8S.

(I must upgrade to Dave CAD at some point)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on April 02, 2016, 04:17:00 pm
For those in the US who are interested in one of the Symmetricom GPSDO's there is a seller on ebay who has a few for 43.99 shipped. To find them you can search for "SYMMETRICOM UCCM", I have no relation to seller, but if they work it is a pretty decent price.

Searching with "SYMMETRICOM UCCM" on EBay doesn't bring anything up other than the seller from China. Do you have a EBAY listing number.

Cheers

Try eBay # 322024166858
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ZigmundRat on April 02, 2016, 09:20:02 pm
or item 252304765793, or 231861995746. Got my second unit from pm_shop_uk (item 322024166858). He was slow to ship (like a week), but the unit arrived and worked fine first time. No missing parts or board damage on this one. And only a little oil :) For $43 a bargain.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 03, 2016, 08:43:00 am
I also used pm_shop_uk for my replacement unit.  It was complete but still needed minor repair. Their return policy is strict so I think it is pot luck with all these units and you should be prepared to gamble and potentially absorb some cost if it doesn't work.
Also... in retrospect I think the initialisation time of this symmetricom uccm-p unit could be an issue, depends if you are prepared to leave it always running or not.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on April 03, 2016, 08:58:18 am
For those in the US who are interested in one of the Symmetricom GPSDO's there is a seller on ebay who has a few for 43.99 shipped. To find them you can search for "SYMMETRICOM UCCM", I have no relation to seller, but if they work it is a pretty decent price.

Searching with "SYMMETRICOM UCCM" on EBay doesn't bring anything up other than the seller from China. Do you have a EBAY listing number.

Cheers

Try eBay # 322024166858

Thanks, although looks like only shipping to the US. Was contemplating having a spare
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 03, 2016, 03:07:35 pm


Thanks, although looks like only shipping to the US. Was contemplating having a spare

Hi

Getting a spare (or three) while these things are cheap is a *really* good idea. All of these gizmos come out in a flood at a low price. Once that initial surge of parts is sold, the prices creep up. A replacement might cost you $250 four years from now. You also might be completely unable to find one at all.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 04, 2016, 11:21:16 pm
Making good progress...  Have got my TFT Touch Screen working with ATMega2560 and added a RS232 converter.

So now I have USB to/from PC as required, RS232 serial to/from UCCM-P and TTL level RX from Fugano GPS for NMEA messages.

The converter was http://www.ebay.co.uk/itm/111927731957 (http://www.ebay.co.uk/itm/111927731957) so my total spend now up to £9.  :)

Still considering whether to route the 6 onboard LEDs straight to equivalents on the front-panel or to Ardunio inputs and drive front-panel LEDs in software...

Incidentally I notice that the device goes to FFOM 0 very quickly, so I don't think survey time is a real issue.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 05, 2016, 08:39:56 am
Well, I just hit the "buy" button on one of this units from this seller here < http://www.ebay.com/itm/331805445560?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/331805445560?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT) >, for 40€ free shipping, let's see how it plays and what conditions it arrives.

NivagSwerdna, that display is looking good.
The FFOM=0 is very good, another one should be TFOM=3 (I think is TFOM).
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 05, 2016, 10:49:08 pm
FWIW The maximum input voltage for the TI DC-DC converter is 5v5.  I would recommend never exceeding 5v1 on the input and not to worry about any high pitched noises during OCXO warm up!  If you go too high on the TI input voltage... it will break.

I found a couple of secret commands tonight..

UCCM-P > :GPS:POS:SURV:STAT?
1
Command Complete


1=Surveying, 0=Position Hold


UCCM-P > :GPS:POS:SURV:PROG?
+2
Command Complete


Survey Progress... 2%

Here's one I like...

UCCM-P > :DIAG:LOG:READ?
"L48:2016-04-05 22:07:56:GPS lock started"
Command Complete


That is the last log entry. Log Entry#, datetime, text


There is this one (mentioned before)...

UCCM-P > :PTIM:TCOD?
T1#H442EFE0020000E2
Command Complete
UCCM-P >


Tells you the time it will be on the next PPS pulse (will block until about 100mS before pulse).  I'm not sure of the format.

also..

UCCM-P > :GPS:POS:SURV ONCE
Command Complete


to force a survey

:SYNC:HOLD:INIT

go to HoldOver

UCCM-P > :SYNC:HOLD:REC:INIT
Command Complete


recover from Hold Over

That's enough for tonight. Time for bed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 06, 2016, 10:54:23 pm
If anyone is interested... here are some TCODE outputs...

T1#H4430443220000B0
T1#H4430443420000B2
T1#H4430443620000B4

I cannot get the checksum calculation to work with these.  I thought it was meant to be the last 2 characters were the HEX of a sum of the ASCII values of the preceeding characters... weird I get 7A, 7C, 7E not B0, B2 and B4.

Must be missing something simple.

I can't find a second serial connection so I am giving up on that.  In fact I think I have investigated as much as I can now. Just need to put it in a box, route the LEDs to the front panel and write a bit of software to display FFOM and TFOM as well as time and position to front-panel.

If you explicitly set position the FFOM will go to zero in just a couple of minutes once the OCXO is warm so I plan to add a function to store surveyed position to EEPROM and restore on start-up.

Too much fun, too little time!

(Also added output from 10MHz and PPS connectors for reference) PPS is 50us width.  [10MHz should read 10MHz not 9.99993MHz but I didn't win a scope in scope month so that's as good as it gets!]
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 07, 2016, 08:48:40 am
NivagSwerdna,

Will you publish the schematic and code?

I think that the display should have position, time, date, TFOM & FFOM, Satellites, for now it's what I can think.

 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 07, 2016, 08:51:20 pm
Will you publish the schematic and code?
Sure.  There isn't much in the way of schematic... it is just Mega2560 clone eBay auction: #272041591038, Display eBay auction: #221831832114 and RS232 Level converter eBay auction: #400461786687.
I will upload the code to github very soon but it's very much a work in progress as I have a day job (actually several!)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 07, 2016, 09:03:00 pm
I know what you mean, to much to do and little time to do it.

I like the infos on the VK4GHZ display on is Trimble, that I suppose that have much more info then the Symmetricom.

BTW my seller add an tracking number to the board for free.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 08, 2016, 07:41:00 am
I like the infos on the VK4GHZ display on is Trimble, that I suppose that have much more info then the Symmetricom.
I wasn't aware of that display but looking at the pictures the Symmetricom UCCM-P has all those details and more (I assume the locator is calculated).
I have a couple of design decisions with the clock display...
Might stay simple with Option 1 for now.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 08, 2016, 03:39:31 pm
Is Trimble LCD is showing several parameters but they are on menus, you can go trough the menus.

This the PDF from the LCD < http://vk4ghz.com/wordpress/wp-content/uploads/Thunderbolt-Display-3-User-Guide.pdf (http://vk4ghz.com/wordpress/wp-content/uploads/Thunderbolt-Display-3-User-Guide.pdf) >.

The locator (Gridsquare) are calculate base on the Lat. and Long, there was some code for arduino to do this, I'll post the link here when I find it.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 10, 2016, 10:54:53 pm
The algorithm for Maidenhead Grid is quite simple if you are converting from WGS-84 so I have added that.... I seem to be in IO91UK

I don't know what the meaning of "10Mhz offst" in ppb on the Thunderbolt display.  For the UCCM-P

The DIAG:LOOP gives...

DIAG:LOOP?
-------------------------------------------------------------------------------
4/10/2016 21:42:57
-------------------------------------------------------------------------------

   LOS      MEAS       NCO STATUS WEIGHT PBUC FBUC DBUC LBUC IBUC G  M TC
-------------------------------------------------------------------------------
 0:  1  0.000e+00  0.000e+00 0x07AC   0   700  700    0    0    2  2  4 29
 1:  1  0.000e+00  0.000e+00 0x068C   0   700  700    0    0    0  2 14 226
GPS: 0 -2.082e-09 -6.762e-09 0x0000   1  ---- 1000 1000 ---- ----  3  6 31
-------------------------------------------------------------------------------
freq cor  = -6.761820e-09
phase cor = 2.000000e-11
gps phase = 3.333333e-09
temp cor  = -2.301801e-11
Command Complete


Not sure which of those many numbers might be equivalent.  Maybe it doesn't matter... FFOM and TFOM enough?

From the Thunderbolt documentation:

10 MHz Offset: This field carries the frequency offset of the 10 MHz output relative to
UTC or GPS as reported by the GPS receiver in ppb (parts-per-billion.) Positive values
indicate that the ThunderBolt’s 10MHz clock is running slow relative to GPS or UTC.


Maybe that is freq cor?  If so the performance of the UCCM -6.761820e-09 is much larger than the very small numbers shown in the Thunderbolt display examples.  Maybe the Thunderbolt is a much better device than the UCCM-P? i.e. at least 2 orders of magnitude better?

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 11, 2016, 11:31:05 pm
Making progress

Source: https://gitlab.com/NivagSwerdna/SymmetricomUCCMDisplay
Schematic: Sketch attached.

Bill of Materials: Arduino ATMega2560 Clone (£5.50 EBAY 100fys), 2.4" TFT Touch Screen Shield (£3 EBAY), Max3232 RS232 level converter module (99p EBAY various sellers).

Only a very initial version but shows what you see below.  Contributions welcomed once it settles down.  I haven't explored the touch screen and menus yet.


(The display is very sharp focused... the blur is my own photographic skill in action)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 12, 2016, 09:40:36 am
Looking very good, still waiting for mine to arrive here.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ghulands on April 14, 2016, 02:08:41 am
I received mine today. A small amount of damage. C36 is hanging on by a trace and C24 is missing. It looks like all those capacitors are the same in that area. Does anyone know the value of them? I'm still waiting for my LCR meter to arrive.

(http://i.imgur.com/mKJe2JRt.jpg) (http://i.imgur.com/mKJe2JR.jpg)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: gm8bjf on April 14, 2016, 12:39:58 pm
Hi ghulands,

I had same problem with one of mine. These caps are associated with the RS232 level shifter IC on the other side of the board. Looking at the data sheetfor the chip I figured that 100nF would not go too far wrong and that worked fine for me.

Brian.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ghulands on April 14, 2016, 02:36:36 pm
Hi ghulands,

I had same problem with one of mine. These caps are associated with the RS232 level shifter IC on the other side of the board. Looking at the data sheetfor the chip I figured that 100nF would not go too far wrong and that worked fine for me.

Brian.

Thanks Brian. 0402 sizing?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 14, 2016, 10:19:07 pm
C23,C24,C25,C35 & C36 look similar
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: gm8bjf on April 15, 2016, 08:19:19 am
Hi ghulands,

I had same problem with one of mine. These caps are associated with the RS232 level shifter IC on the other side of the board. Looking at the data sheetfor the chip I figured that 100nF would not go too far wrong and that worked fine for me.

Brian.

Thanks Brian. 0402 sizing?

Hi,

I think that they should be, but I used 0805s as they were what I had to hand.

Brian.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 17, 2016, 02:47:38 pm
Can someone who understands these things please explain....

Does the accuracy of the frequency increase with time?  Is that observable from the measurements in DIAG:LOOP?

I was thinking that if I am only going to use this thing to calibrate my other instruments (frequency counter and function generator) I do not need to leave it on for long periods of time however if it benefits from staying on for long periods then I should also make it serve NTP to increase its usefulness.

Advice please.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 17, 2016, 03:10:18 pm
Can someone who understands these things please explain....

Does the accuracy of the frequency increase with time?  Is that observable from the measurements in DIAG:LOOP?

I was thinking that if I am only going to use this thing to calibrate my other instruments (frequency counter and function generator) I do not need to leave it on for long periods of time however if it benefits from staying on for long periods then I should also make it serve NTP to increase its usefulness.

Advice please.

Hi

Yes, the frequency accuracy increases with time. For best results, you need a well surveyed location (which takes time). You also need to allow the OCXO to fully stabilize (which might take a week or two). You also need to get the disciplining loop into it's lowest state. That may only occur after the OCXO has stabilized. It might occur in a couple of days. Digging into the specific firmware on your unit would be the only way to really know.

How much of a difference does a couple days make? In the ideal case, you likely will go from down about 2X every time you double the time on past the first day out to a few weeks. The ultimate floor will depend on your antenna location, the quality of the survey, and the temperature stability of your lab. With a crummy antenna and a drafty lab, you might not see any improvement past the second day ...

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on April 17, 2016, 06:21:22 pm
Does the accuracy of the frequency increase with time?  Is that observable from the measurements in DIAG:LOOP?

I was thinking that if I am only going to use this thing to calibrate my other instruments (frequency counter and function generator) I do not need to leave it on for long periods of time however if it benefits from staying on for long periods then I should also make it serve NTP to increase its usefulness.

Accuracy is a bit of a slippery concept when applied to GPSDOs.  Assuming that it's working correctly, the average output frequency of a GPSDO doesn't change.  However, it will wander around a little since GPS has to deal with path-length variations due to the ionosphere.  The main purpose of the OCXO is to act as a flywheel to filter out the wander.

If you look here:  http://www.leapsecond.com/pages/gpsdo/ (http://www.leapsecond.com/pages/gpsdo/) , particularly the last graph, you'll see performance graphs for 4 GPSDOs.  Notice the 'hump' in the graphs that have the dots.  These humps show the crossover between the performance of the OCXO and the GPS system.  It's a balancing act between short-term GPS noise and long-term OCXO aging.  Most commercial GPSDOs have to take a middle-ground, 'good enough' path and the hump is the typical result.  Some commercial GPSDOs actually do some autotunig to adapt to the oscillator's performance.  If you look here:  http://www.leapsecond.com/pages/tbolt-tc/ (http://www.leapsecond.com/pages/tbolt-tc/) , you'll see a discussion about tuning a Trimble Thunderbolt to match the performance of the OCXO in that particular unit.  The results are impressive.

The performance of a good quality OCXO will improve if it's allowed to run continuously.  Aging in particular will drop.  This would allow for a longer time constant in your control loop and therefore, a lower, longer flatter portion of the AlDev curve before it hits the sloped GPS performance line.  Proper tuning will minimize or eliminate any hump.

But does this matter?  If you look back to the performance graph for the 4 GPSDOs, they're all around 1e-12 @ 1 sec.  which is a common measurement interval.  You'll have to decide whether improvements at 10, 100, or 1000 seconds are useful to you.  I just measured the frequency of my Z3801A GPSDO.  With a one second gate time, I'm seeing a Standard Deviation of about 200 - 300 uHz.  A 10 second gate time drops that to less than 50 uHz.  My counter is a Fluke PM6681.  My Efratom FRT Rb standard is the external reference.  These numbers are not as good as the ones shown in the graph.  Each OCXO has its own unique performance level.  The OCXO in my Z3801A might not be as good as the one shown in the graphs.

As for the DIAG:LOOP parameters, there isn't really enough info to say much about them.  Watch and record them.  See how they change as the unit runs for days or weeks.  Do they wander up and down?  Do they slowly stabilize?  I would expect frequency offset to wander because the OCXO will continuously flywheel to buffer the wander from GPS.  There will always be an offset that varies up and down.  But if that 'TC' parameter stands for 'Time Constant', you might see it slowly increase as the OCXO settles down.  That would show you that your GPSDO is doing some autotuning.

Ed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 17, 2016, 06:48:11 pm
Hi

If *frequency* accuracy is of interest, then ADEV (especially at 1 second) is probably not a good measure on a GPSDO. At 1 second, you are looking at the free running performance of the OCXO. You get great numbers, but the accuracy might only be as good as the OCXO's. You need to wait long enough that the GPS section has had time to get the OCXO settled down in order for the accuracy of the GPS system to transfer in a meaningful way to the OCXO.

A simple experiment:

Yank the antenna on the GPSDO and look at the ADEV. The numbers inside 10 seconds look no different than the numbers with the antenna connected. The OCXO *could* be off anywhere.

Leave the antenna off and watch the ADEV plot of the OCXO. As the unit stabilizes (over days / weeks), the curve past 10 seconds flattens out. The longer it is on, (in a stable environment) the flatter it is likely to get. That may continue out past 1,000 seconds or it may start to turn up a bit. The flatter that curve is, the better the short term frequency of the OCXO will be compared to the long term.

Yes, it would be nice if the ADEV curve dropped off as 1/sqrt(tau). That's not what happens in an OCXO. The physics don't work that way.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 17, 2016, 08:09:29 pm
Not sure how I would get ADEV?

But I think that's exactly my question... At startup you effectively get the OCXO performance and then the OCXO becomes gradually disciplined by the GPS PPS signal.  So when am I confident it is at least accurate to 1mHz in 10MHz.  Which I presume is 1e-10?

Looking at the DIAG:LOOP numbers they don't seem to change much over several days. 

Code: [Select]
-------------------------------------------------------------------------------
4/10/2016 21:42:57
-------------------------------------------------------------------------------

   LOS      MEAS       NCO STATUS WEIGHT PBUC FBUC DBUC LBUC IBUC G  M TC
-------------------------------------------------------------------------------
 0:  1  0.000e+00  0.000e+00 0x07AC   0   700  700    0    0    2  2  4 29
 1:  1  0.000e+00  0.000e+00 0x068C   0   700  700    0    0    0  2 14 226
GPS: 0 -2.082e-09 -6.762e-09 0x0000   1  ---- 1000 1000 ---- ----  3  6 31
-------------------------------------------------------------------------------
freq cor  = -6.761820e-09
phase cor = 2.000000e-11
gps phase = 3.333333e-09
temp cor  = -2.301801e-11
Command Complete

-------------------------------------------------------------------------------
4/17/2016 20:03:32
-------------------------------------------------------------------------------

   LOS      MEAS       NCO STATUS WEIGHT PBUC FBUC DBUC LBUC IBUC G  M TC
-------------------------------------------------------------------------------
 0:  1  0.000e+00  0.000e+00 0x07AC   0   700  700    0    0    2  2  4 29
 1:  1  0.000e+00  0.000e+00 0x068C   0   700  700    0    0    0  2 14 226
GPS: 0 -7.138e-09 -6.458e-09 0x0000   1  ---- 1000 1000 ---- ----  3  6 31
-------------------------------------------------------------------------------
freq cor  = -6.458316e-09
phase cor = -2.000000e-11
gps phase = 1.033333e-08
temp cor  = -3.138324e-11
Command Complete


and now...

Code: [Select]
-------------------------------------------------------------------------------
4/20/2016 08:25:29
-------------------------------------------------------------------------------

   LOS      MEAS       NCO STATUS WEIGHT PBUC FBUC DBUC LBUC IBUC G  M TC
-------------------------------------------------------------------------------
 0:  1  0.000e+00  0.000e+00 0x07AC   0   700  700    0    0    2  2  4 29
 1:  1  0.000e+00  0.000e+00 0x068C   0   700  700    0    0    0  2 14 226
GPS: 0 -8.632e-09 -6.277e-09 0x0000   1  ---- 1000 1000 ---- ----  3  6 31
-------------------------------------------------------------------------------
freq cor  = -6.276511e-09
phase cor = -2.000000e-11
gps phase = 1.533333e-08
temp cor  = -1.841605e-11
Command Complete
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 17, 2016, 08:16:12 pm
I find this page http://www.gb3hm.co.uk/gps/UCCM.htm (http://www.gb3hm.co.uk/gps/UCCM.htm) quite interesting... seems to be the same unit.  Can anyone interpret those graphs a bit for me?

My unit is currently saying...

Code: [Select]
UCCM-P > SYSTem:STATus?
-------------------------------------------------------------------------------
090-03861-03   serial number W560935175   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     2             FFOM     0
                                              UCCM-P Status[ACTIVE]

>> GPS: [phase:  1.27e-08]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 4 ____   Not Tracking: 5 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      20:17:52     17 APR 2016
  7  12 329   39    10  16 153                GPS      Synchronized to UTC
  8  17 275   35    16  76 255                ANT DLY  +5.000E-08
 20  23  50   44    18  34 117                Position ________________________
 21  59  71   35    26  59 168                MODE     Hold
                    27  48 279
                                              LAT      N  51:25:23.472
                                              LON      W   0:17:26.922
                                              HGT                +2.70 m  (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------

Command Complete

Maybe ACQUISITION isn't a disciplined state?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on April 17, 2016, 08:25:50 pm

If *frequency* accuracy is of interest, then ADEV (especially at 1 second) is probably not a good measure on a GPSDO. At 1 second, you are looking at the free running performance of the OCXO. You get great numbers, but the accuracy might only be as good as the OCXO's. You need to wait long enough that the GPS section has had time to get the OCXO settled down in order for the accuracy of the GPS system to transfer in a meaningful way to the OCXO.

Hi Bob,

The ADEV graph is still useful to show where and how the OCXO and GPS performance curves merge.  Whether ADEV is necessary isn't clear to me since the main purpose of ADEV is to filter out OCXO parameters like aging that confuse normal mathematical variance calculations.  The GPSDO cancels those out.

The assumption here is that the GPSDO being measured has had enough operating time for the GPSDO to correct any OCXO frequency error.  i.e. the OCXO is locked to GPS.  The OP wanted to know if that's all that's necessary.  The answer is no, but the OP will have to decide whether the differences are significant.

At 1 second, ADEV shows you the noise aka jitter performance of the OCXO which is mostly independent of GPS.  The frequency situation may not be as well determined, but in any practical GPSDO, the OCXO isn't going to be bouncing off the walls.  The locked status prevents a frequency offset as averaged over the length of the discipling loop's time constant.  But OCXO frequency changes over periods less than the time constant would still show up as poor ADEV.  If there are no frequency changes, there can't be a frequency offset.

Quote
A simple experiment:

Yank the antenna on the GPSDO and look at the ADEV. The numbers inside 10 seconds look no different than the numbers with the antenna connected. The OCXO *could* be off anywhere.

Okay, using 10 seconds as an example of the loop time constant.  Can I revise your statement to say "If you freeze the disciplining loop, the numbers inside 10 seconds look no different than the numbers with the loop active."?  I'm sure you know that some smart GPSDOs can compensate for OCXO aging during holdover conditions.  I'm playing to the audience here.  :)  Yes, the OCXO *could* be off anywhere, but if it was doing that, you would have been warned by the poor short-term ADEV while it was in the locked condition.  So, in practice, that won't occur.

Quote
Leave the antenna off and watch the ADEV plot of the OCXO. As the unit stabilizes (over days / weeks), the curve past 10 seconds flattens out. The longer it is on, (in a stable environment) the flatter it is likely to get. That may continue out past 1,000 seconds or it may start to turn up a bit. The flatter that curve is, the better the short term frequency of the OCXO will be compared to the long term.


Bob, I totally agree with you on this point.  This is standard OCXO behaviour.  They like to run continuously and if you let them they will continue to improve - typically beyond their factory specifications.  Sometimes, with top-grade OCXOs, they can approach Rb standards for long-term aging.  So, as your OCXO improves, you'd like to increase your time constant to make the best use of the OCXO's low noise performance while still using GPS to cancel out the aging.  This is why the OP might want to run his GPSDO continuously - so the OCXO reaches its maximum potential.  Whether that matters is up to him.

Quote
Yes, it would be nice if the ADEV curve dropped off as 1/sqrt(tau). That's not what happens in an OCXO. The physics don't work that way.

Bob, you totally lost me on that point.  Did I imply something about 1/sqrt(tau) ?  :-//

Ed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on April 17, 2016, 09:00:56 pm
Not sure how I would get ADEV?

But I think that's exactly my question... At startup you effectively get the OCXO performance and then the OCXO becomes gradually disciplined by the GPS PPS signal.  So when am I confident it is at least accurate to 1mHz in 10MHz.  Which I presume is 1e-10?

Looking at the DIAG:LOOP numbers they don't seem to change much over several days. 


You get ADEV by sending the data from your counter to a computer and then giving it to an ADEV program.  A program like Timelab combines those and lets you use either RS-232 or GPIB to collect the data and generates the graph automatically - if your counter is supported.

If your goal is 1 mHz accuracy, it shouldn't take very long.  Unfortunately, we don't have specs for these units.  However, the HP/Symmetricom Z38xx units use the same terminology and commands (mostly).  The Z3801A specifies a 10 MHz error of < 1e-9 averaged over 1 day (See note below).  They say that the spec is reached when the FFOM is <= 2.  GPS has improved since that manual was written (2000) so the performance of even an old GPSDO will be significantly better than spec.  But without measuring it, I can't say how much better or when you'd reach your 1 mHz goal.  I suspect that if you wait for an FFOM of 0 you'd be fine.

If you've had your unit running for a week or two, the loop parameters might have settled almost as much as they're going to.  Some GPSDOs remember the OCXO's behaviour even over a power cycle, so you might not be able to see a lot of variation even if you cycled the power.

Ed

Note:  I just looked at the specs for an HP 58540A Time & Frequency Receiver.  It's in the same family as the Z38xx units.  The manual, also dated in 2000, states that the 10 MHz accuracy is <= 1e-11 averaged over one day.  I don't understand why there would be so much difference in specs for the two units.  I doubt that there's much real difference between the Z3801A and the 58540A.


Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 17, 2016, 10:39:11 pm
Not sure how I would get ADEV?

But I think that's exactly my question... At startup you effectively get the OCXO performance and then the OCXO becomes gradually disciplined by the GPS PPS signal.  So when am I confident it is at least accurate to 1mHz in 10MHz.  Which I presume is 1e-10?

Looking at the DIAG:LOOP numbers they don't seem to change much over several days. 


You get ADEV by sending the data from your counter to a computer and then giving it to an ADEV program.  A program like Timelab combines those and lets you use either RS-232 or GPIB to collect the data and generates the graph automatically - if your counter is supported.

If your goal is 1 mHz accuracy, it shouldn't take very long.  Unfortunately, we don't have specs for these units.  However, the HP/Symmetricom Z38xx units use the same terminology and commands (mostly).  The Z3801A specifies a 10 MHz error of < 1e-9 averaged over 1 day (See note below).  They say that the spec is reached when the FFOM is <= 2.  GPS has improved since that manual was written (2000) so the performance of even an old GPSDO will be significantly better than spec.  But without measuring it, I can't say how much better or when you'd reach your 1 mHz goal.  I suspect that if you wait for an FFOM of 0 you'd be fine.

If you've had your unit running for a week or two, the loop parameters might have settled almost as much as they're going to.  Some GPSDOs remember the OCXO's behaviour even over a power cycle, so you might not be able to see a lot of variation even if you cycled the power.

Ed

Note:  I just looked at the specs for an HP 58540A Time & Frequency Receiver.  It's in the same family as the Z38xx units.  The manual, also dated in 2000, states that the 10 MHz accuracy is <= 1e-11 averaged over one day.  I don't understand why there would be so much difference in specs for the two units.  I doubt that there's much real difference between the Z3801A and the 58540A.

Hi

Here's the issue:

The "averaged over a day" number simply indicates that the phase lines up to some degree over 24 hours. The "frequency" being used is really frequency as delivered by GPS time. For practical use, it is not the number you think it is. The OCXO could swing +/- 1 ppm and hit that spec.

The more important spec if you are interested in frequency is -- how close is it if I use a gate time of ____ ? Normal numbers are 1, 10, and 100 seconds. The gotcha is that there is no closed form solution to that measure. (Which is why we have ADEV). About all you can say is: If I want it to be correct 99% of the time, what is the limit? Consider that with thousands of samples in a day, with 1 or 10 second gates, having 1% out still is a lot of errors.

You don't see the 99% spec on the cell tower GPSDO's. It was not part of the master specification on the units. The frequency limit in the master spec was 1x10^-8 which is pretty silly in this context. Over the first day a typical unit will hit < 1 ppb on a 99% basis. That will evolve to about 0.1 ppb pretty quickly (day 2 or 3). It will progress into the 0.1 to 0.01 ppb range, but probably will not exceed 0.01 ppb unless you have a *really* good OCXO.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on April 17, 2016, 11:20:07 pm
Not sure how I would get ADEV?

But I think that's exactly my question... At startup you effectively get the OCXO performance and then the OCXO becomes gradually disciplined by the GPS PPS signal.  So when am I confident it is at least accurate to 1mHz in 10MHz.  Which I presume is 1e-10?

Looking at the DIAG:LOOP numbers they don't seem to change much over several days. 


You get ADEV by sending the data from your counter to a computer and then giving it to an ADEV program.  A program like Timelab combines those and lets you use either RS-232 or GPIB to collect the data and generates the graph automatically - if your counter is supported.

If your goal is 1 mHz accuracy, it shouldn't take very long.  Unfortunately, we don't have specs for these units.  However, the HP/Symmetricom Z38xx units use the same terminology and commands (mostly).  The Z3801A specifies a 10 MHz error of < 1e-9 averaged over 1 day (See note below).  They say that the spec is reached when the FFOM is <= 2.  GPS has improved since that manual was written (2000) so the performance of even an old GPSDO will be significantly better than spec.  But without measuring it, I can't say how much better or when you'd reach your 1 mHz goal.  I suspect that if you wait for an FFOM of 0 you'd be fine.

If you've had your unit running for a week or two, the loop parameters might have settled almost as much as they're going to.  Some GPSDOs remember the OCXO's behaviour even over a power cycle, so you might not be able to see a lot of variation even if you cycled the power.

Ed

Note:  I just looked at the specs for an HP 58540A Time & Frequency Receiver.  It's in the same family as the Z38xx units.  The manual, also dated in 2000, states that the 10 MHz accuracy is <= 1e-11 averaged over one day.  I don't understand why there would be so much difference in specs for the two units.  I doubt that there's much real difference between the Z3801A and the 58540A.

Hi

Here's the issue:

The "averaged over a day" number simply indicates that the phase lines up to some degree over 24 hours. The "frequency" being used is really frequency as delivered by GPS time. For practical use, it is not the number you think it is. The OCXO could swing +/- 1 ppm and hit that spec.

The more important spec if you are interested in frequency is -- how close is it if I use a gate time of ____ ? Normal numbers are 1, 10, and 100 seconds. The gotcha is that there is no closed form solution to that measure. (Which is why we have ADEV). About all you can say is: If I want it to be correct 99% of the time, what is the limit? Consider that with thousands of samples in a day, with 1 or 10 second gates, having 1% out still is a lot of errors.

You don't see the 99% spec on the cell tower GPSDO's. It was not part of the master specification on the units. The frequency limit in the master spec was 1x10^-8 which is pretty silly in this context. Over the first day a typical unit will hit < 1 ppb on a 99% basis. That will evolve to about 0.1 ppb pretty quickly (day 2 or 3). It will progress into the 0.1 to 0.01 ppb range, but probably will not exceed 0.01 ppb unless you have a *really* good OCXO.

Bob

Yes, the 'one day' figure by itself is open to a lot of interpretation.  I think the Z3801A manual is just a reissue of an older manual and so doesn't spec things very well.  The 58540A manual however, also specs the ADev as <= 5e-10 @ 1 sec. one hour after initial lock, so frequency swings of even 1 ppb are unlikely.  But you're correct that they don't give a 99% spec.

But that still doesn't help us with this Symmetricom unit.  I don't have one so I have no measurements to share.  Measuring a GPSDO can be a challenge.  Tau values of > ~1000 sec. aren't necessary because GPS sets the performance.  In any case, it's easy to make those measurements.  But measuring at short tau values at these levels requires some effort and equipment.

Ed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on April 17, 2016, 11:45:39 pm
This is good stuff guys. I think there are quite a few of us that would like to understand the best way to compare GPSDO's to really determine how(if?) they are performing.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 18, 2016, 12:36:48 am
Not sure how I would get ADEV?

But I think that's exactly my question... At startup you effectively get the OCXO performance and then the OCXO becomes gradually disciplined by the GPS PPS signal.  So when am I confident it is at least accurate to 1mHz in 10MHz.  Which I presume is 1e-10?

Looking at the DIAG:LOOP numbers they don't seem to change much over several days. 


You get ADEV by sending the data from your counter to a computer and then giving it to an ADEV program.  A program like Timelab combines those and lets you use either RS-232 or GPIB to collect the data and generates the graph automatically - if your counter is supported.

If your goal is 1 mHz accuracy, it shouldn't take very long.  Unfortunately, we don't have specs for these units.  However, the HP/Symmetricom Z38xx units use the same terminology and commands (mostly).  The Z3801A specifies a 10 MHz error of < 1e-9 averaged over 1 day (See note below).  They say that the spec is reached when the FFOM is <= 2.  GPS has improved since that manual was written (2000) so the performance of even an old GPSDO will be significantly better than spec.  But without measuring it, I can't say how much better or when you'd reach your 1 mHz goal.  I suspect that if you wait for an FFOM of 0 you'd be fine.

If you've had your unit running for a week or two, the loop parameters might have settled almost as much as they're going to.  Some GPSDOs remember the OCXO's behaviour even over a power cycle, so you might not be able to see a lot of variation even if you cycled the power.

Ed

Note:  I just looked at the specs for an HP 58540A Time & Frequency Receiver.  It's in the same family as the Z38xx units.  The manual, also dated in 2000, states that the 10 MHz accuracy is <= 1e-11 averaged over one day.  I don't understand why there would be so much difference in specs for the two units.  I doubt that there's much real difference between the Z3801A and the 58540A.

Hi

Here's the issue:

The "averaged over a day" number simply indicates that the phase lines up to some degree over 24 hours. The "frequency" being used is really frequency as delivered by GPS time. For practical use, it is not the number you think it is. The OCXO could swing +/- 1 ppm and hit that spec.

The more important spec if you are interested in frequency is -- how close is it if I use a gate time of ____ ? Normal numbers are 1, 10, and 100 seconds. The gotcha is that there is no closed form solution to that measure. (Which is why we have ADEV). About all you can say is: If I want it to be correct 99% of the time, what is the limit? Consider that with thousands of samples in a day, with 1 or 10 second gates, having 1% out still is a lot of errors.

You don't see the 99% spec on the cell tower GPSDO's. It was not part of the master specification on the units. The frequency limit in the master spec was 1x10^-8 which is pretty silly in this context. Over the first day a typical unit will hit < 1 ppb on a 99% basis. That will evolve to about 0.1 ppb pretty quickly (day 2 or 3). It will progress into the 0.1 to 0.01 ppb range, but probably will not exceed 0.01 ppb unless you have a *really* good OCXO.

Bob

Yes, the 'one day' figure by itself is open to a lot of interpretation.  I think the Z3801A manual is just a reissue of an older manual and so doesn't spec things very well.  The 58540A manual however, also specs the ADev as <= 5e-10 @ 1 sec. one hour after initial lock, so frequency swings of even 1 ppb are unlikely.  But you're correct that they don't give a 99% spec.

But that still doesn't help us with this Symmetricom unit.  I don't have one so I have no measurements to share.  Measuring a GPSDO can be a challenge.  Tau values of > ~1000 sec. aren't necessary because GPS sets the performance.  In any case, it's easy to make those measurements.  But measuring at short tau values at these levels requires some effort and equipment.

Ed

Hi

Unfortunately 1 second ADEV tells you only that the standard deviation of the frequency change second to second (after drift is removed) is some number. It tells you nothing about the average change at all. The system can be cycling 1 ppm up and down and still hit a 5 x 10^-10 ADEV. It will have to do it very slowly. That's exactly what GPSDO steering does (change things slowly). Is it likely (or even possible) that it swings a ppm? No, it's not and it doesn't do that. The point is simply that it *could* do that and a 1 second ADEV would not catch it.

If you are going to evaluate a 1 second 99% spec at the 1x10^-11 level, you pretty much must have a Hydrogen Maser to compare it to. Anything else (including a high performance tube in a 5071) isn't going to do the job. There are a few other bits and pieces you will need, but the maser rules out most of us common folk.

Another approach is to compare two GPSDO's of different designs against each other. That can lead to all sorts of tangles. Yet another approach is to take the gate time out to > 100 seconds and a 5071 *might* do the job with some hand waving involved. Needless to say, you don't see many GPSDO's with a 1 second 99% confidence point at 1x10^-11 guaranteed by 100% testing.

Bob

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on April 18, 2016, 04:03:37 am
Unfortunately 1 second ADEV tells you only that the standard deviation of the frequency change second to second (after drift is removed) is some number. It tells you nothing about the average change at all. The system can be cycling 1 ppm up and down and still hit a 5 x 10^-10 ADEV. It will have to do it very slowly. That's exactly what GPSDO steering does (change things slowly). Is it likely (or even possible) that it swings a ppm? No, it's not and it doesn't do that. The point is simply that it *could* do that and a 1 second ADEV would not catch it.

If you are going to evaluate a 1 second 99% spec at the 1x10^-11 level, you pretty much must have a Hydrogen Maser to compare it to. Anything else (including a high performance tube in a 5071) isn't going to do the job. There are a few other bits and pieces you will need, but the maser rules out most of us common folk.

Another approach is to compare two GPSDO's of different designs against each other. That can lead to all sorts of tangles. Yet another approach is to take the gate time out to > 100 seconds and a 5071 *might* do the job with some hand waving involved. Needless to say, you don't see many GPSDO's with a 1 second 99% confidence point at 1x10^-11 guaranteed by 100% testing.

Bob

Luckily, we're just hobbyists so we don't have to worry about 99% of anything.  :)  For that matter, we don't even have to produce definitive results, although they should be repeatable.  As you say, we don't have Hydrogen Masers.  I happen to have a Cs standard, but it's not a magic bullet either.  John Ackerman did some GPSDO comparisons that highlighted both good results and traps for young players.  http://www.febo.com/pages/gpsdo_comparison/ (http://www.febo.com/pages/gpsdo_comparison/) .  Beyond that, we can muddle around and see what happens.  I've wondered what the results would be if I used the 'three-cornered hat' technique to compare three GPSDOs.  Maybe I or someone else here will find that out.

It's all good! :-+

Ed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 18, 2016, 06:59:17 am
Simplistically, So if I wait 10^4 seconds (presumably after hold reached) then I should have got a good chunk of quality out of my box?  10,000s is about 3 hrs?

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on April 18, 2016, 03:26:45 pm
Simplistically, So if I wait 10^4 seconds (presumably after hold reached) then I should have got a good chunk of quality out of my box?  10,000s is about 3 hrs?

Yes, but if it takes that long to reach an acceptable level (i.e. FFOM = 0), personally, I'd just let the thing run 24/7.  A 3 hour warmup time would drive me crazy.  I have a really old Rb standard that takes almost an hour to warm up.  By the time it's ready to go I'm practically gnawing on the furniture in frustration.  |O

Ed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 18, 2016, 10:40:53 pm
Simplistically, So if I wait 10^4 seconds (presumably after hold reached) then I should have got a good chunk of quality out of my box?  10,000s is about 3 hrs?

Hi

GPSDO's go through a series of filter adjustments as the OCXO warms up and the unit stabilizes. You only get through the first part of the process 24 hours. Running for at least three days is about the minimum for reasonable accuracy.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on April 18, 2016, 11:40:24 pm
Simplistically, So if I wait 10^4 seconds (presumably after hold reached) then I should have got a good chunk of quality out of my box?  10,000s is about 3 hrs?

Hi

GPSDO's go through a series of filter adjustments as the OCXO warms up and the unit stabilizes. You only get through the first part of the process 24 hours. Running for at least three days is about the minimum for reasonable accuracy.

Bob

Hi Bob,

Can you give an estimate of what 'reasonable accuracy' would be?  We're flying blind with this Symmetricom GPSDO.  We have no docs, no specs, and no clue what the design requirements were.  But if it was telco equipment, the start-up phase might have been very loosely defined since it was likely intended for 24/7 operation.  It appears to be from WiMax equipment.  And remember that NivagSwerdna is only looking for 1 mHz accuracy for the 10 MHz output.

Ed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on April 19, 2016, 12:28:30 am
Probably just as hard to find the specs of the equivalent Trimble units.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 19, 2016, 12:37:54 am
Simplistically, So if I wait 10^4 seconds (presumably after hold reached) then I should have got a good chunk of quality out of my box?  10,000s is about 3 hrs?

Hi

GPSDO's go through a series of filter adjustments as the OCXO warms up and the unit stabilizes. You only get through the first part of the process 24 hours. Running for at least three days is about the minimum for reasonable accuracy.

Bob

Hi Bob,

Can you give an estimate of what 'reasonable accuracy' would be?  We're flying blind with this Symmetricom GPSDO.  We have no docs, no specs, and no clue what the design requirements were.  But if it was telco equipment, the start-up phase might have been very loosely defined since it was likely intended for 24/7 operation.  It appears to be from WiMax equipment.  And remember that NivagSwerdna is only looking for 1 mHz accuracy for the 10 MHz output.

Ed


Hi

Is the unit capable of doing position hold to a prior survey?

If so, is the unit previously surveyed in and that position saved?

Right there you have a process that will take longer than the 3 hours he's talking about. While it's in survey mode ... no bets at all about accuracy.

How good is the antenna location?

How many sat's are locked on at all times?

If the answer is "always > 6, usually more than 8" that's a long way from "usually 6" that some antenna locations give you. A good antenna with 360 degree view to the horizon will do a survey pretty quick (hours). An antenna that keeps going down to and below 4 sats could take days.

How long has the unit been power off?

An OCXO may move a few ppb in the first hour and not settle down for quite a while if it's been off power for weeks / months / years. It will do a lot better if it has been on power for months and was only turned off for a couple of minutes. The control loop has a tough time just tracking the nutty GPS wander. Throw in the OCXO moving like crazy and it's going to do worse.

Which version of the HP / Symmetricom firmware is in these units?

I have seen some of them that are moving in the 10 mHz for the first 24 hours after turn on. It's not a one sided sort of "always gets better" kind of thing. It's swinging back and forth in frequency to keep the time aligned. On those units, you can still see very distinct changes in the disciplining over the first couple of days.

How picky are you?

There have been posts made of people doing plots of these sort of units showing > 1 mHz (on 10 MHz) swings after over a month on power. They many not do it often, but it can "hang out" in that region for an hour or more.

Lots of variables. The only safe answer is to keep it on power for multiple days.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 19, 2016, 08:14:24 am
Is the unit capable of doing position hold to a prior survey?
Yes.  Indeed I programmed my display to save the result of the survey to EEPROM and I can load this after a cold restart.  I haven't timed it exactly but after a cold restart, and after OCXO warmup the unit will go to FFOM=0 within approx. 10 minutes of having its prior position re-loaded.

I'm a bit sceptical about short term performance,... in particular I am not sure what parameters the unit stores between cold starts, if it remembers a few things I can see it could restore and get itself rapidly quite close but it doesn't seem to remember much (e.g. it forgets initial position)

If the PPS of the GPS is accurate to 100nS (which I seem to remember from a Fugano spec) then that is only 10e-7 so I can see it rapidly getting to 10e-7 once a GPS lock has been achieved (although obviously it would need to converge on that solution somehow).  If I am after 10e-9 then that definitely seems to imply some time... 10 mins is 600 seconds, maybe that is enough.

I thought I knew my racal-dana 1998 frequency counter was out... It was showing 9.999793 but then I left it and the GPSDO running and came back two days later and it reads..  9.999993

I guess I'll never be sure of the frequency of anything ever again!



Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 19, 2016, 11:44:11 am
Hi

The simple answer it to let your GPSDO run continuously. That is the environment they were intended to be used in. The firmware in the unit was all targeted at an "always on" situation. The only specification that really matters on them is "holdover". That is: how long will time pulse output stay within some limit (say 1.5 us for 4 hours) after the antenna is unplugged. Even that has a bunch of "after three days on power" sort of qualifications on it.

Bottom line - it's just a happy coincidence that these gizmos put out accurate frequency. We all use them that way, but they were not designed with that as a primary goal. The specs don't talk about it and the firmware is not optimized to do it.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on April 19, 2016, 06:29:09 pm
Bottom line - it's just a happy coincidence that these gizmos put out accurate frequency. We all use them that way, but they were not designed with that as a primary goal. The specs don't talk about it and the firmware is not optimized to do it.

Are you talking about this Symmetricom unit specifically or all GPSDO's in general?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 19, 2016, 09:05:34 pm
The simple answer it to let your GPSDO run continuously.
Looks like it's getting a Raspberry Pi and doubling as a NTP server then!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 19, 2016, 11:32:27 pm
Bottom line - it's just a happy coincidence that these gizmos put out accurate frequency. We all use them that way, but they were not designed with that as a primary goal. The specs don't talk about it and the firmware is not optimized to do it.

Are you talking about this Symmetricom unit specifically or all GPSDO's in general?

Hi

All of the GPSDO's that:

1) Are OCXO based
2) Were designed for wireless com use
3) Came from Trimble and HP / Symmetricom
4) Were sold in high enough volumes that you can *find* multiple examples

Have a *lot* in common with each other. That's even more true when you narrow it down to gear made by Trimble or just to gear made by HP / Symmetricom. You can look at the lockup profile on an early Trimble and see the same thing going on with their new stuff. The same is true of the way the early HP's chug through settings in the same way the later Symmetricom designs do. So yes, this is similarity and taking lotos of data on a few hundred GPSDO designs over the years.

Are they identical? Certainly not. They targeted different holdover specifications and have different OCXO's as a result. The early ones used a lot more components to get the job done than the later ones. Some have more extensive command sets that others. The early ones came out in big sturdy enclosures. The later stuff is barely more than a pc board with parts on it. Some specific examples if this model have an OCXO from supplier A and others have an OCXO from supplier B. One or the other likely does a little better.

All of these units require a good antenna location. They all need to (somehow) be put into position hold mode. They all work best when on power continuously. The cosmetic differences are bigger than the model to model variations when using them as a frequency standard in a normal "alway on" lab environment. They are lower cost, lower power, higher reliability, and longer life than any of the Rb's or Cs standards you commonly come across on eBay. Yes you have to shop a bit for the lower cost part. Yes you *can* find GPS disciplined Rb's on rare occasions.

Yes, that's a long and rambling answer to a fairly simple question.

Bob

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on April 19, 2016, 11:56:50 pm
OK, I just got the sense you were implying(well you said it) that it is only a happy coincidence they generate an accurate frequency. Considering several HP models say "Frequency reference" on them I'd like to think they were specifically designed with accurate frequency in mind. One of mine says "reference clocks" and doesn't supply any 1 PPS etc so the only thing it is doing is providing an accurate frequency output.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 20, 2016, 01:40:50 am
OK, I just got the sense you were implying(well you said it) that it is only a happy coincidence they generate an accurate frequency. Considering several HP models say "Frequency reference" on them I'd like to think they were specifically designed with accurate frequency in mind. One of mine says "reference clocks" and doesn't supply any 1 PPS etc so the only thing it is doing is providing an accurate frequency output.

Hi

It is abundantly unclear if the HP "frequency reference" units actually are supposed to be different than the cell tower / wireless designs. A *lot* of what you see sold as the lab units are cell tower surplus that has been re-packaged in China in the pretty desktop enclosure. When you get one, a very real question to ask is "what i*is* this beast?". At least in my highly informal survey, 9 times out of 10, it's a cell tower unit with cell tower firmware in it.

That said, yes, you can target the firmware at frequency instead of time. You also can target something other than holdover performance. I have never seen a lab environment that actually used / needed / wanted / cared about holdover. Doing all the heavy lifting to get that done takes a bit of gear and quite a bit of time. For the investment, it's better to do the work on an Rb than on an OCXO. You will invest a lot and you might as well have the better result. The cost of the Rb is trivial compared to the other gear and your time. The downside of the Rb is that with a > 48 hour loop, they take a *long* time to test and tweak in. Getting to 10 or 20 time constants just for settling is a while. You also will spend some time on pressure and temperature compensation.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kilobyte on April 20, 2016, 12:09:41 pm
Hi,

I got my UCCM today and saw that U22 ist missing.

Can someone look what's the Part Marking on U22?
I think it could be some sort of a singlegate and/or logic.

If i have cleaned up the oily PCB i will take some highres photos because i didn't find any yet.

Regards
Kai
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on April 20, 2016, 02:46:57 pm
Can someone look what's the Part Marking on U22?
It's a 5 pin SOT marked Z32H. I reckon NC7SZ32 (https://www.fairchildsemi.com/datasheets/NC/NC7SZ32.pdf) :-+
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uski on April 20, 2016, 09:31:19 pm
I got my UCCM today and saw that U22 ist missing.

Can someone look what's the Part Marking on U22?
I think it could be some sort of a singlegate and/or logic.

I suggest you open a dispute with the seller immediately and ask for a refund. Then, use the money to buy another one.

DO NOT ACCEPT THAT HE SEND A REPLACEMENT. He was supposed to do it for me, but he never sent anything, and this let the dispute delay expire so I didn't get anything back. The seller flyxy2015 is a thief. Just wanted to warn you guys.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on April 20, 2016, 09:51:14 pm
I think calling him a thief is a bit too much. I guess he doesn't have any idea what he is selling is working or not and he should list it as such. However, they are cheap - and there is a reason for it. The market price would appear to include that risk. There are many examples of how these boards turn up in this thread alone.

He could easily have more goodwill for sure if he was more honest, but ultimately he is at ebays/paypals mercy and a full refund is on offer. Clearly he has costed this into his business model selling scrap boards. I'm sure he thinks lots of his customers are thieves too, even me because I ultimately got mine for free (though not in my time, effort, and a couple of quid fixing the fucking thing  :-DD)

Seriously, when you are dealing with scrap boards coming from China you should have your wits about you and be willing to write off the transaction, even though you are guaranteed a full refund by AliExpress or ebay, etc.

The guy is not a thief. Just a typical Chinese businessman.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kilobyte on April 20, 2016, 10:15:56 pm
Can someone look what's the Part Marking on U22?
It's a 5 pin SOT marked Z32H. I reckon NC7SZ32 (https://www.fairchildsemi.com/datasheets/NC/NC7SZ32.pdf) :-+

Thanks for the info Macbeth.
I will try it first with some singlegate 74ahc32 from a old scrap pcb. Should be good enough for a quick test.

I didn't powered the UCCM yet, because the U22 is missing.
If it will work then I'm happy and if it doesn't work then I can still ask for a refund.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uski on April 20, 2016, 10:40:38 pm
I think calling him a thief is a bit too much. I guess he doesn't have any idea what he is selling is working or not and he should list it as such. However, they are cheap - and there is a reason for it. The market price would appear to include that risk. There are many examples of how these boards turn up in this thread alone.

He could easily have more goodwill for sure if he was more honest, but ultimately he is at ebays/paypals mercy and a full refund is on offer. Clearly he has costed this into his business model selling scrap boards. I'm sure he thinks lots of his customers are thieves too, even me because I ultimately got mine for free (though not in my time, effort, and a couple of quid fixing the fucking thing  :-DD)

Seriously, when you are dealing with scrap boards coming from China you should have your wits about you and be willing to write off the transaction, even though you are guaranteed a full refund by AliExpress or ebay, etc.

The guy is not a thief. Just a typical Chinese businessman.

He agreed to send a new board. He lied and never did. Scrap board or anything else, it's the same, he lied, this should not be accepted.

I've been dealing with chinese sellers for years. I know how it works. I'm generally reasonable. But when someone promises you something and they don't fulfill their promise, then they steal.

It's simple...

I'd like to add that he increased the prices quite a bit. So he's making a very decent profit. We're not speaking about a poor guy making $0.1 per transaction. He's making at least $25 per transaction, considering the recent price increase. At that price, he should behave differently.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on April 21, 2016, 12:07:34 am
uski, your not wrong. I mean he had me with the same "ok - i send one out!". But I just used the ebay/paypal rules against him when he couldn't prove he sent a replacement (which he obviously didn't). I am very surprised you got stung and didn't actually get a refund.

But yes, this guy is right at the sleazy end of Chinese sellers. Most are very good.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: grumpydoc on April 21, 2016, 05:45:15 am
I got a replacement without much argument.

But it appears he then put me in his blocked buyer list  :--
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on April 21, 2016, 05:58:24 am
I got a full refund when the trimble unit I ordered from him didn't show. It did arrive after 2 + months finally, and had a few small caps ripped off the board.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 22, 2016, 04:54:54 pm
I managed to get the UCCM-P, display and Raspberry Pi hooked up with the same kernel variant I used for my prior NTP server.
The Furano PPS is just tapped off and seems to work OK with the Pi (this goes in via GPIO 18)

Code: [Select]
root@ntpi:/etc# ppstest /dev/pps0
trying PPS source "/dev/pps0"
found PPS source "/dev/pps0"
ok, found 1 source(s), now start fetching data...
source 0 - assert 1461343553.000001559, sequence: 3585 - clear  0.000000000, sequence: 0
source 0 - assert 1461343554.000001046, sequence: 3586 - clear  0.000000000, sequence: 0
source 0 - assert 1461343555.000001533, sequence: 3587 - clear  0.000000000, sequence: 0
source 0 - assert 1461343556.000001019, sequence: 3588 - clear  0.000000000, sequence: 0
source 0 - assert 1461343557.000001506, sequence: 3589 - clear  0.000000000, sequence: 0
source 0 - assert 1461343558.000001994, sequence: 3590 - clear  0.000000000, sequence: 0
^C

I translate the $PFEC,GPtps messages which I am already receiving into $GPRMC ones and send to RPi (I have a spare UART in the Arduino2560).

Then use the NMEA refclock driver.... that's the theory anyway...

From clockstats...

Code: [Select]
57500 71382.283 127.127.20.0 $GPRMC,194942,A,0.0,N,0.0,W,0.0,0.0,220416,0.0,E*54
I don't know enough about NTPd to tell if this is good or not...

Code: [Select]
pi@ntpi ~ $ ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
oPPS(0)          .PPS.            0 l    3   16  377    0.000    0.001   0.002
xGPS_NMEA(0)     .GPS.            0 l   50   64  377    0.000   36.874   3.410
*ptbtime1.ptb.de .PTB.            1 u    2   64  175   47.091   -4.047   0.539
-pyxis.my-rz.de  36.224.68.195    2 u    7   64  377   35.558   -2.520   0.358
-cipher-code.de  129.70.132.32    3 u    4   64  377   35.602   -6.459   3.421
+ntp.atomki.mta. .GPS.            1 u   12   64  377   53.283   -5.236   2.095
+195.50.171.101  145.253.3.52     2 u   46   64  377   31.870   -4.044   0.236
pi@ntpi ~ $


Using config...

Code: [Select]
# pps-gpio on /dev/pps0
server 127.127.22.0 minpoll 4 maxpoll 4
fudge 127.127.22.0 refid PPS
fudge 127.127.22.0 flag3 1  # enable kernel PLL/FLL clock discipline

#NMEA
#server 127.127.20.0 mode 17
server 127.127.20.0 mode 65553 time1 0.7

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kilobyte on April 22, 2016, 06:42:00 pm
So, I've repaired my Symmetricon GPSDO successfully with a SN74AHC1G32 from an old PCB and with some enamelled copper wire.
Without U22 it says something like "FPGA error" on startup.

Next step is to order some MCX to SMA/BNC pigtails
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 22, 2016, 07:28:49 pm
Well I'm jealous of you guys,mine still haven't arrive.
Let's see what damage it shows or what missing parts are not there.

My seller was "waikeionline_uk", he gave free tacking number and free shipping for 40€.
The tracking number shows that it arrive at Portugal on 15 of this month, so 1 week in the customs and counting, I hope I don't have to pay the VAT + Customs expenses.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on April 22, 2016, 09:13:21 pm
My seller was "waikeionline_uk"

I ordered 2 more from waikeionline_us, and they both arrived broken.

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=219181;image)

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=219179;image)

So I sent him the pictures and he asked me if I wanted a refund or replacement. I told him I want a replacement if he can send unbroken working ones (like he says on ebay: working).
Then he asked me to send the broken ones back and I told him that it would cost me $20 ( eur 16.50) for registered mail. So he refunded me $20 from the original payment... hmmm, not exactly fair but ok. Let's see how things progress. Clearly they were sent broken because the packing was sealed an the missing part was not in the package.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 22, 2016, 09:35:43 pm
I'm still trying to get a refund from flyxy2015.  He asked me to send it back and we eventually managed to get the US$20 shipping transferred to me, still waiting for a proper refund or replacement... I haven't given up on him yet... it will either end up in a replacement or a refund.  I would be a bit worried with a partial refund... might be worth asking EBAY.

The damage appears to be consistent with other boards... i.e. it shows what happens when you brute force the board out.

I resoldered my L20... was hanging off like yours.  Likewise my C1 was a bit bent, not as bad as yours!

L3 is an inductor...  Coilcraft marked 333 on my board (33uH?)

Also check the bottom very carefully... I had a missing cap on the bottom.

I don't think it is unreasonable for them to get the board back if they are giving a replacement/refund but they should pay the postage (just make sure you file as Not As Described).


Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on April 22, 2016, 09:52:41 pm
I looked at L20 thinking I could resolder it but couldn't find the wires, it ripped off badly.
And yes, one of the boards also has some damage on the other side:

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=219195;image)

I offered him $20 for the broken boards thinking that I could maybe fix one or both, but he didn't agree.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on April 24, 2016, 09:25:05 am
Hi Daniel
Yes please that would be brill,i wish I could do that,
Thanks Dave 2E0DMB

Here it is. Please tell me if it works, this way I can send the fix to the original author.


Cheers.
---
Daniel

Re:
https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg849732/#msg849732 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg849732/#msg849732)

Any change of getting the sourcecode , or at least a description of the differences against the below source 

Afficheur-GPS-V2.22-Source
http://www.f4ctz.fr/?page_id=692&aid=1282&sa=1 (http://www.f4ctz.fr/?page_id=692&aid=1282&sa=1)

I'm using AVR not PIC

/Bingo
I sent the patch this week for the furuno support to F4CTZ, I think he will made it available soon (full source code or patch only, I don't know).

Cheers.
---
Daniel

Any luck in the author able to post the changes (source, changes), checked the site and didn't see anything new.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 24, 2016, 09:44:31 am
Please could someone suggest how I could convert the single 10MHz out to a dual output so I can plug it into my Racal-Dana 1999 Frequency counter ans Siglent 1025 Function Generator simultaenously.  A Fan-out Clock Buffer?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 24, 2016, 11:36:15 am
Here is one http://www.f4ctz.fr/?page_id=891&lang=en (http://www.f4ctz.fr/?page_id=891&lang=en)
OZ2M make one with 10 outputs for about 100€
Mini Circuits also sells some
G4HUP have another http://www.g4hup.com/DA/DA1_4.htm (http://www.g4hup.com/DA/DA1_4.htm)
Another one http://www.stable32.com/An%20Octal%2010%20MHz%20Distribution%20Amplifier.pdf (http://www.stable32.com/An%20Octal%2010%20MHz%20Distribution%20Amplifier.pdf)
DEMI also sells some
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 24, 2016, 01:01:12 pm
Please could someone suggest how I could convert the single 10MHz out to a dual output so I can plug it into my Racal-Dana 1999 Frequency counter ans Siglent 1025 Function Generator simultaenously.  A Fan-out Clock Buffer?

Hi

Are you looking for something to build (a schematic) or something to buy (a rack mount distribution amp) ?

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 24, 2016, 04:48:29 pm
Definitely build and I want it super simple.  I assume all I really need is a buffer amp, probably got something suitable in the junk box.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on April 24, 2016, 05:36:08 pm
On most test equipment, the External Reference input is NOT 50 ohm.  It's usually much higher - typically in the hundreds of ohms.  So you don't need any kind of splitter or distribution amp.  Just use a BNC T connector and daisy-chain one cable from one piece of equipment to the next.  Maybe finish off the cable with a 50 ohm terminator.

I checked your Racal 1999 and although I didn't see a spec, the schematic shows that the impedance will be over 500 ohms.  I couldn't find any info on the Siglent 1025.

Ed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on April 24, 2016, 05:41:52 pm
Definitely build and I want it super simple.  I assume all I really need is a buffer amp, probably got something suitable in the junk box.

Hi

Ok, super simple (but not a Tee):

Run the signal into the input of a NS7SZ125 or any similar single gate. AC couple it through a 0.1 uf cap and bias it with a pair of 10K resistors to put 1/2 Vcc on the input. You now have a (sort of) square wave at the output of the gate at 10 MHz. You can play with the bias a bit if you want 50/50 duty cycle.

Next run that into however many gates you need to drive your outputs. Put 100 ohms in series with the output and 100 ohms to ground (50 ohm source). AC couple that to a coax connector and you have the drive for your gizmo. If you want to get exotic, put a two inductor one capacitor Tee lowpass filter in place of the two resistors.

None of the parts are critical. None of the values are critical. Just use something as fast as 74AC or faster (no 74HC or 4000 series).

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SeanB on April 24, 2016, 07:02:59 pm
Just look locally for a used video distribution amplifier. Those typically have 2 inputs, switchable termination, and you can swap out the terminator resistor to a 56R one to make it 50R input, and then replace the 75R output resistors with 51R ones to get a 50R output. You get from 2 to 4 outputs per side, or at least 4 outputs for a single input. While not technically rated for 10MHz, as video is really only going to 7MHz, they typically will do around 15MHz before the gain drops off to less than unity.

I have been tossing them out recently, though I still have one left in a 1U rack format, which has 4 inputs and each has 16 outputs. A little much for the OPAMP LABS potted modules to drive, I have had to fix 2 of them to replace burnt out power transistors, seeing as they use a BC237/BC337 pair inside. Replaced with 2N2219/2N2905 with push on heatsinks, using the original LM709 opamp inside, though the tantalum caps in it and some of the board did not survive the epoxy removal, but a bodge wire and some new resistors and diodes and it worked.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on April 24, 2016, 09:32:56 pm
Please could someone suggest how I could convert the single 10MHz out to a dual output so I can plug it into my Racal-Dana 1999 Frequency counter ans Siglent 1025 Function Generator simultaenously.  A Fan-out Clock Buffer?

The schematics are all here if you wanted to roll your own vs the kit.

https://www.tapr.org/kits_tadd-1.html (https://www.tapr.org/kits_tadd-1.html)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on April 25, 2016, 04:41:45 am
...

Any luck in the author able to post the changes (source, changes), checked the site and didn't see anything new.

Yes, code has been merged, unified version should be release sooner or later.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 25, 2016, 07:43:47 pm
Is there a +ve and -ve regulated supply on the board?

The reason I ask is that looking at the 10MHz output... https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg913093/#msg913093 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg913093/#msg913093) it is exactly the right shape so drive both my counter and my function generator. I believe the Siglent spec is 3v3 pp and the Racal counter something similar.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 26, 2016, 11:20:57 am
Hi all,

Mine just arrive this morning, board with oil, missing GPS connector, on the top, that I can see.

On the bottom missing C73, in the middle of U20 and U16, missing one C or R left of R89 and the U next to it.

The rest of the pads doesn't seem to ever been solder, the solder mask is intact.

Two pictures of Hi resolution, here < https://onedrive.live.com/redir?resid=A26220D7C8CFDD26!11112&authkey=!AILPETMicS4LO8A&ithint=folder%2cJPG >.

Can you guys spot anything else I might have overlook.
 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 26, 2016, 08:45:31 pm
Indeed you have C73 missing as I did.  No idea how they managed to lose that one!

In the section between C119 and R89 I also have an unpopulated chip spot so I don't think you have that part missing.

If you look super close it's quite easy to spot the genuinely missing components as the pads are rough

Your board is pretty typical, shame about the antenna connector but again par for the course.. I guess the soldering wasn't good enough to cope with the loving dismantling the board went through in its last hours.

(You should delete the out of focus images; my eyes are squiffy now)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on April 26, 2016, 08:49:40 pm
Is there a +ve and -ve regulated supply on the board?

The reason I ask is that looking at the 10MHz output... https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg913093/#msg913093 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg913093/#msg913093) it is exactly the right shape so drive both my counter and my function generator. I believe the Siglent spec is 3v3 pp and the Racal counter something similar.
I haven't found any negative rails on the board. You are thinking of op-amps that require +/- supplies maybe?

I would suggest that the 10MHz is simply capacitor coupled - hence the lack of any DC. Trap for young players or maybe I don't quite understand??  ;)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 26, 2016, 09:03:05 pm
Indeed I'm in the bottom of a young player trap.  I've been doing some research and I think I like the look of LT6551 and perhaps some elements of the TAPR circuit... especially like the 1:1 RF Transformer.  Looks like I can achieve what I want with very few components.  This project is a huge distraction... I never intended to get a GPSDO!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 26, 2016, 09:19:48 pm
Indeed you have C73 missing as I did.  No idea how they managed to lose that one!

In the section between C119 and R89 I also have an unpopulated chip spot so I don't think you have that part missing.

If you look super close it's quite easy to spot the genuinely missing components as the pads are rough

Your board is pretty typical, shame about the antenna connector but again par for the course.. I guess the soldering wasn't good enough to cope with the loving dismantling the board went through in its last hours.

(You should delete the out of focus images; my eyes are squiffy now)

Thanks for the help, can you measure the C at the right of that chip, I'm my board is missing that one.

I've deleted the out of focus, sorry for that, I've just upload everything.

So let's see tomorrow what I got here.

 The power (+5V) is plug on the fuse where it says F1?
Where is the GND?

Or is there some better places?

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 26, 2016, 09:24:47 pm
I soldered +5V to the end of the fuse F1 and GND to the end of the big Tantalum Cap above that.

Incidentally, the ribbon cable (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg893582/#msg893582 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg893582/#msg893582)) has a group of pins that are 5V and then a group of pins that are GND.

Do not exceed 5v1
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on April 26, 2016, 09:57:24 pm
Do not exceed 5v1
Also power up with at least 1.7A CC. I've found anything much below makes the DC/DC converter go into self destruct mode, whistling away, clamping the DC down to ~3V... It's also not DP832 PSU friendly, try a higher CC on that or find another supply... My guess is an unregulated would make that TI PTN04050C happy as it doesn't fight the constant current mode.  :-//
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 27, 2016, 01:04:14 pm
Well I've one PSU 15V 35A, so power shouldn't be a problem.

I just have to find the value for C73 and for the C at the left of R89 and right of the chip, on the bottom side of the board.

I suppose C73 should be similar of C94, bypass cap 0.1uF  :-//.
I've here some 100nF 50V and 25V, maybe it will do ???

But the other I don't have any clue.  :-//
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on April 27, 2016, 01:39:45 pm
Had a look at my board and they are both bypass caps, so 0.1u should be fine.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 27, 2016, 01:55:57 pm
Had a look at my board and they are both bypass caps, so 0.1u should be fine.

Thanks PA0PBZ, I'll put the two back in, and take another look at the board, then power it up, to see if it lights up anything.
I've measure C62 and C94 and they measure 28.78µF at 120Hz.  :-//

SMA in smd on it's way, to replace all the connectors.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kutte on April 27, 2016, 04:55:07 pm
hi to all,
received my Symmetricom board yesterday. As to be exspected some damage could be seen. On the top side xtal y1 is missing, inductor L20 was ripped off. On the botton side capacitor C26 and resistor R83 were missing.
R83 could be easily identified as 103 (10kOhm), C26 is in neighbourhood of C27 which I measured as 1.2 uF. I put in 0.56 uF as a provisory measure.
Inductor L20 I measured as 5uH and replaced with a new one. Since xtal Y1 is missing, I suggested it to be 22.118.400 Hz. Is there any kind soul able to confirm this value?
Unit seems to be working fine when injecting 22118400 Hz from an external generator.
regards Goetz
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 27, 2016, 05:42:31 pm
My Y1 is mark as B22.11840.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on April 27, 2016, 06:10:44 pm
I've measure C62 and C94 and they measure 28.78µF at 120Hz.  :-//

You are measuring one of the power lines, there's a lot of parallel caps on there :)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 27, 2016, 06:20:33 pm
Ok then 100nF 25V in there, then let's see if it can bring the magic.

Will try with one little GPS antenna that I've here in the bin, don't know if it's active or not.

I've one TTL to mini USB from other project will try to connect it.

Will power it with 6V from an 35A power supply, should be enough.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on April 27, 2016, 06:28:54 pm
I've one TTL to mini USB from other project will try to connect it.

The port is RS232 level, not TTL.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 27, 2016, 07:23:04 pm
Will power it with 6V from an 35A power supply, should be enough.
Indeed, should be enough to fry the onboard DC-DC converter which is rated at 5.5V MAX.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 27, 2016, 07:48:17 pm
The port is RS232 level, not TTL.

Doing more than one thing at same time, gives this.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 27, 2016, 07:49:37 pm
Will power it with 6V from an 35A power supply, should be enough.
Indeed, should be enough to fry the onboard DC-DC converter which is rated at 5.5V MAX.

So 5 or close enough, should be better. :-)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 27, 2016, 08:45:03 pm
The GPS module RX/TX are at TTL levels.  The board serial I/O, as appears on the pin header, is at RS232 levels.  You can interface with both.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 28, 2016, 10:03:47 am
I've power it today with around 5V after soldering the C73 and also the cap near R89 and the chip, replace both with 100nF 25V caps.
When power DS1 will start red, DS2 will start green, DS1 will go out and DS2 will start blinking green.
DS3 and DS4 will start red, DS3 will turn steady green, DS4 go out, but after a few he came back with both red and green leds light up.
The GPS doesn't have an antenna connected, and even with the antenna connected is the same.

The OCXO is getting warmer as the time pass.

Is this behavior normal on the led's?

Only got one RS232 to TTL module.

Update: I got the attach from one program, but can't find one that let me send commands to the GPS, the file was grap on the GPS pinout, with one TTL to RS-232 USB converter.

What program do you guys use for terminal to send the commands?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 28, 2016, 07:18:15 pm
re: flashing LEDs

Probably; Not sure what they all do, even less sure what they do in fault condition.  In happy state there is a 1Hz Green flasher and a more rapid Green flasher.

You really need to interface with the RS232 level pin-header, that is where you do fun stuff.

Snooping on TX from GPS to GPSDO is good for driving a display or NTP server.  I see you have SV with 0 satellites, not surprising with no antenna!
You can also snoop on RX which shows commands from GPSDO but you can't inject there since it is driven by the GPSDO.

Get a RS232 interface going.

I use Putty because it's on my PC for other things but there are others... RealTerm?

You're not going to get far without an antenna!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 28, 2016, 08:24:34 pm
NivagSwerdna thanks.

Well the antenna was an old one from the junk box, I've open it and found it with water and all rusty inside, so no antenna at all. (Maybe this is the cause of the state of DS4?)
Will have to order a new one, don't know yet if one small or one bigger one.

Tomorrow will add one DB9 and connect directly to the DB9 on the PC.

I've Putty also and RealTerm, will have to look better to see where to send the commands.

Regarding the Led's, I'm not sure also about what they do, but all the voltages on the testing points are present and spot on. (I can put here my measurements of the testing points tomorrow).

The OCXO will warm up.



Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 28, 2016, 09:05:12 pm
re: Antenna eBay auction: #201464346512 is what I have
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on April 28, 2016, 11:23:17 pm
eBay auction: #201464346512 is what I have

That looks exactly the same as mine!

@Nuno_pt

You really want to use the terminal at the RS232 port which is pretty obvious really. Quite strange to go straight in and tap the GPS receiver? All the LEDs will match up with the STATUS, SYST:STAT and other diagnostics. You also have an error log to examine. Looking at LED's will leave you in the dark  :-DD
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 29, 2016, 10:58:00 am
>>> All the LEDs will match up with the STATUS, SYST:STAT and other diagnostics.
It's not really that obvious though is it?

The wiring shows... https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg909870/#msg909870 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg909870/#msg909870)

4 LEDs, two of which are dual LED... i.e. 6 LEDs in total.

The green sides of both dual LED are driven by the FPGA, otherwise all the others are driven by the microcontroller.  The command LED:GPSLock? seems to suggest that one might correlate to GPS Lock.... maybe the 1Hz flasher?

The mapping isn't obvious.


Code: [Select]
UCCM-P > STATus

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [Master]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warm]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [NORMAL 2 MODE]
Command Complete

Code: [Select]
UCCM-P > SYSTem:STATus?
-------------------------------------------------------------------------------
090-03861-03   serial number W560935175   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     2             FFOM     0
                                              UCCM-P Status[ACTIVE]

>> GPS: [phase:  1.00e-08]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 6 ____   Not Tracking: 4 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      10:37:32     29 APR 2016
 10  15 323   42    12  10 205                GPS      Synchronized to UTC
 13  53 130   32    15  77 234                ANT DLY  +5.000E-08
 17  23  98   34    20  27 219                Position ________________________
 18  32 292   34    24  48 267                MODE     Hold
 19  11 128   34
 28  37  52   43                              LAT      N  51:25:23.592
                                              LON      W   0:17:26.904
                                              HGT                +9.30 m  (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------

Command Complete
UCCM-P >
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 29, 2016, 11:20:05 am
Morning,

I'll have to move my PC, from the other room to my bench if I want to have native RS-232, on the bench I only have a laptop with USB.
I've here one of this converters eBay auction: #http://www.ebay.com/itm/FT232RL-FTDI-Serials-Adapter-Module-Mini-Port-f-Arduino-USB-to-TTL-3-3V-5-5V-GM-/262136733739?hash=item3d0891202b, from what I could find in the web, on the pins we can plug the TTL levels like I was doing yesterday for the Furuno.

But on the sides there are holes for other connections, on the web they say that an cable to RS-232 can be connected on the side holes.

Board ----> RS-232
TXD  ----> Pin 3
RXD ----> Pin 2
GND ----> Pin 5

Will this work?
Since they pass to the FTDI chip and exit the Mini-USB.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 29, 2016, 11:52:26 am
If you have a fancy modern PC with only USB then you need a eBay auction: #262312697328 USB to old fashioned RS232 DB9 flavour serial.

You will need 3 wires... GND, RX and TX.

If it is a male DB9 connector on the adapter then... GND is top far right (pin 5) and RX/TX are pins 2 and 3 (can't remember which way around)

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on April 29, 2016, 12:03:59 pm
Those USB to 232 converters work very well , or you could go Bluetooth
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on April 29, 2016, 12:13:50 pm
I was asking because if the one that I've will do it, I can start debugging, if not will have to order one.

From what I can see my board has on the sides, all the marks need for RS-232.
 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on April 29, 2016, 12:44:47 pm
Simple Answer: Get a RS232 level interface
Medium Answer: Get a RS232/TTL converter like this... eBay auction: #401099454734 and use your existing gadget
Complex answer: You could remove the SP3232E and interface at TTL levels

My solution interfaces at TTL level to snoop on the TX from the GPS and I interact with the main part of the board at RS232 levels using a level converter.
I didn't want to unnecessarily modify the UCCM-P so I use the headers.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on May 01, 2016, 10:20:54 pm
...

Any luck in the author able to post the changes (source, changes), checked the site and didn't see anything new.

Yes, code has been merged, unified version should be release sooner or later.

Great, will keep an eye out for it.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 03, 2016, 07:09:24 pm
Today I've taken the RS-232 PC from another division of the house and bring it to the bench.

I've try first the loopback on the RS-232 by shunting pins 2 & 3 together, using Putty I set it to use COM1 9600 8N1 Xon&Xoff.
Loopback works great, what I type on the keyboard appears on Putty.
So I attach one RS-232 cable straight, female on the PC side and male on the GPS side.
From the GPS pins I use cables from the arduino *female to female* to plug into the cable male connector.
I've start Putty, when typing * ? * the same character appears on Putty, so the Loopback is working.
If I change the RX and TX on the GPS pins, nothing happens.   
Also if I connect pin 5 to pin 5, that is GND, there is no caracter on the screen only garbage.

Anyone have some test that I can do, or more ideas how I can try it to see if I get something out of the GPS.

I can put screen shot's.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on May 03, 2016, 07:26:54 pm
Hi you need to change your baud rate to 57600 8N1 no flow
control
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on May 03, 2016, 07:33:13 pm
Hi 9600baud is just for the GPS module  and that is at TTL
Level
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 03, 2016, 08:34:12 pm
Hi Dave,

Thanks for the replay, I'll try 57600 tomorrow, I see that I'm using " Xon/Xoff ", and should be using " None " instead.

Yes the TTL levels from the Furuno itself work very well at 9600 8N1 Xon/Xoff with and TTL to Mini USB adapter.

I'll report here the same experience but at 56700 8N1 None
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 03, 2016, 08:40:39 pm
57600-8-N-1

From my male USB to serial adapter....

Looking into the pins with the 5 pins in top row, 4 pins in lower row, top row, Pin 1 on left, Pin 5 on right

Pin 2 ------------ Blue Wire   --------------------------  TX
Pin 3 ------------ Pink Wire   ---------------------------RX
         ----------  Not connected ------------------------  BT
Pin 5 ------------ Green Wire  ------------------------- GD

Flow control None (but XON/XOFF will also work)

You do need to get the device started... with my dodgy power supply I have to wait for 10 mins until the OCXO is warm before it resets fully and LEDs flicker etc.

Once started you should see...

Code: [Select]
Symmetricom Boot Code ver. 1.01.01


Press Enter to go to boot
Image1: [1.0.0.2] [454535 bytes] [valid checksum:0x20AFA24] [timestamp:3]
Image2: [1.0.0.1] [454535 bytes] [valid checksum:0x2142B89] [timestamp:2]

Loading Image1
UCCM-P >

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 03, 2016, 09:03:08 pm
Thanks NivagSwerdna,

I can't open my cable, the DB9's are sealed.
But I extend the output of the male connector with female to female dupon cables from arduino, one side to the DB9 male pins the other side to the GPS pins.
I was using 9600 8N1 XON/XOFF, let's see if it works tomorrow.
If not maybe I've to send the board back.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 03, 2016, 09:21:24 pm
Mine is plug almost all day, power supply here is not a problem, it's on 5V but it has 35A, so no problem with current to the OCXO.

I've check all the voltages on the test points, all of them are spot on, the OCXO will be hot, the led's work, so no problem to plug it in and leave it alone for 10 or 20 minutes to see that code.

That code appears by itself, after you connect successful at the COM port, but without typing anything on Putty, correct?

I still don't have the GPS antenna, it's on order, also the RS-232 to TTL, SMA connectors, MCX to SMA cables, and for display I want to see if a friend of mine want's to donate one of is 3.2'' TFT.
Raspberry 3 is also on order to make a Stratum 1, and I'm looking at G4HUP 10MHz distribution amplifier.

This will be put in one box, to feed the lab with 10MHz.

If all work well, another one with only 10MHz will follow for the Ham station to plug the transverter's and radios.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 03, 2016, 10:44:06 pm
I can't open my cable, the DB9's are sealed.
The cable colours were just my patch leads, nothing clever intended.  No opening of any cables.
Incidentally, I have taken to powering mine with 6v (which is above max for the onboard boost converter) but I need some headroom over 5v for the mega2560 regulator, it hasn't blown up yet.
re: communications.... you get the bootup message at board reset.  (You can get this to happen by pressing RST), otherwise you need to send a command e.g. "?"
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on May 04, 2016, 01:02:46 am
Hi Dave,

Thanks for the replay, I'll try 57600 tomorrow, I see that I'm using " Xon/Xoff ", and should be using " None " instead.

Yes the TTL levels from the Furuno itself work very well at 9600 8N1 Xon/Xoff with and TTL to Mini USB adapter.

I'll report here the same experience but at 56700 8N1 None

You can also adjust the RS232 header to a different baud rate by using one of the two and select your baud rate.

SYSTem:COMMunication:SERial1:BAUD 9600|19200|38400|57600
or
SYSTem:COMMunication:SERial2:BAUD 9600|19200|38400|57600

I think it's the second one.

Just a note your settings won't stick after a reboot, although I think the following may store the setting, just never tried it

SYSTem:COMMunication:SERial1:PRESet
SYSTem:COMMunication:SERial2:PRESet
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 04, 2016, 09:05:04 am
Morning all,

It's working, I can issue commands, and get replays.

I issue the STATUS command, and get the following, see attach.

The PC doesn't have internet there, waiting for the WiFi USB pen's, so can't paste the code directly here.

The #Operation Alarm is ok, since I don't have yet the antenna connected, but the rest is ok, I suppose.
If I issue an ALARm:OPERation? It returns Antenna fail, because there is no antenna connected yet.
If I issue an OUTPut:STATe, it returns UNLOCK.

If you want that I issue other commands to see if the board is ok, just let me know.

Update:
BOM order:
Arduino Mega - http://www.ebay.com/itm/400935362320?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/400935362320?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
GPS Antenna - http://www.ebay.com/itm/261953407322?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/261953407322?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
SMA 90º connector - http://www.ebay.com/itm/271265210952?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/271265210952?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
MCX to SMA cable - http://www.ebay.com/itm/281108847224?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/281108847224?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
RS-232 to TTL converters - http://www.ebay.com/itm/400461786687?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/400461786687?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

Next order will be:
TFT 3.2" - http://www.ebay.com/itm/3-2-inch-TFT-LCD-module-Display-with-touch-panel-SD-card-240x320-touch-pen-beu-/182070719728?hash=item2a6442b4f0:g:TQEAAOSw0vBUj-1t (http://www.ebay.com/itm/3-2-inch-TFT-LCD-module-Display-with-touch-panel-SD-card-240x320-touch-pen-beu-/182070719728?hash=item2a6442b4f0:g:TQEAAOSw0vBUj-1t)

Raspberry 3 - For NTP Server (Stratum 1)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 05, 2016, 08:53:54 pm
I think I'm almost done... Just got to split my 10MHz two ways and then I can get on with my original project!

I wired the LEDs on the UCCM-P to digital inputs,  on the front panel I have 4 dual colour (RED/GREEN) LEDs that are then driven by the microcontroller.  Currently it is just passed through but I think I might change the logic as the rapid green flashing is a bit annoying, think I might make that a stable Green.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 05, 2016, 09:12:01 pm
Very well, I like it, big thumbs up.
 
Where do you pick the led's?
On the resistores or on the Led´s.
Can you take a picture of it?

Between the TFT and the Mega is that a shield for the TFT?

Can you show the connections to the Pi, I got here 2 Pi2, don't know if I use this or order one Pi3.

For mine I'll use one kit of 8 exit's on 10MHz from G4HUP.

I want to have all here to chose the box type, to accommodate all, GPSDO, Rasp, 10MHz amp.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 05, 2016, 09:21:39 pm
These are my connections on the bottom of the board.  (Horrible... this was my first attempt it's much neater now)...

As per... https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg909870/#msg909870 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg909870/#msg909870)

Connections are on driven side of the LEDs (i.e. opposite side to resistor).  I left the board LEDs in place.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 05, 2016, 09:36:11 pm
Thanks for the photos, I've some work for tomorrow, the GPS hack I've it too but I don't think that I've those pins there, Pin 3 is ok, but Pin 5 I don't think I've that one tap.

Is the Rasp picking the 1PPS pulse ok?
Seems some complains about it be too short 10uS or so, and the Rasp can't get it, so some use 74AC to increase it to 225 to 250uSe
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 06, 2016, 07:50:23 am
I use the GPS PPS not the UCCM-P.  It is plenty wide enough.  I wasn't worried about operating in holdover mode. (Also the GPS pulse is synchronised to UTC, no idea what the guarantees of the UCCM-P PPS pulse are other than being 1Hz)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 06, 2016, 10:39:14 am
I only saw that you're using the Furuno PPS NMEA sentence after writing the replay.
Yes the only advantage of taking the PPS of the MCX is the 1Hz, the circuit of the PPS taken out of the MCX is very simple so I might try it and see what I get.
It's just taking the 1PPS from the MCX feed it to an 74AC and create an divider, two outputs and another to the Raspberry.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 06, 2016, 03:53:41 pm
I use the PPS signal from the GPS module for the PPS for NTPd, this is 500ms on/500ms off, with the rising edge being synchronised to UTC.  (I also used the NMEA $PFEC,GPtps message from the GPS TX pin for the NMEA reference clock for raw time).

I compared the PPS from the UCCM-P with the GPS and I guess it is not surprising that they are in phase (after all this is the driver for the discipline of the LO).  So it makes no difference which you use for the NTPd.  The advantage of the UCCM-P being it continues, with disciplined OCXO accuracy, during holdover whereas the GPS module has only its local oscillator to remain in sync.

UCCM-P is 50us width probably best stretched to 20ms or so if using for Pi GPIO.

I tried using a pulse stretcher circuit (attached), introduces around 1us delay, stretches to just over 20ms with a 82k and 0.1uF.  Not sure which signal I will use now!

Attached a couple of screenshots.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: GI1CET on May 06, 2016, 07:35:39 pm
Got one of these and i have been reasonably lucky but..

GPS fine
OCXO fine but not being disciplined and the only damage I can find is a missing U26 and a displaced cap
Anyone know what U26 should be?

Thanks in advance
Jim
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on May 06, 2016, 07:48:38 pm
Hi is it just me but your board looks all black And burnt
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on May 06, 2016, 07:52:26 pm
This is U26, not sure what it is:

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=222857;image)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on May 06, 2016, 07:53:43 pm
Hi Jim
If you find it is a Z04 Inverter, I can send you one, as I have
Some left after fixing mine
Dave 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: grumpydoc on May 06, 2016, 07:56:45 pm
This is U26, not sure what it is:

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=222857;image)
My guess would be a single gate and given the "08" marking probably a single AND gate.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on May 06, 2016, 08:01:46 pm
My guess would be a single gate and given the "08" marking probably a single AND gate.

Yes, that would be a good guess. I could of course take it from the pcb, power it up and measure what it does but it is too small for my old eyes  :(
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: grumpydoc on May 06, 2016, 08:09:54 pm
Yes, that would be a good guess. I could of course take it from the pcb, power it up and measure what it does but it is too small for my old eyes  :(
With you on that one - I can barely do anything electronic without a stout magnifying glass :(
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on May 06, 2016, 09:11:34 pm
FWIW mine is marked T08B (or T088) and has 3 dots all in line from bottom left.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on May 06, 2016, 09:21:42 pm
FWIW mine is marked T08B (or T088) and has 3 dots all in line from bottom left.

Interesting, T08 SOT-753 is a  74HCT1G08GV, AND gate indeed.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: GI1CET on May 07, 2016, 08:48:44 am
Dave, 2E0dmb

No its not, I just didn't play with the lighting when taking the photo ;-)

Jim, GI1CET
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: GI1CET on May 07, 2016, 08:54:35 am
All

Thanks for that incredibly useful info  i will source some 74HCT1G08GV and get the iron hot, many thanks

will report results here but it may be delayed as I am back and forth to the Mainland non stop for the next few weeks so not much time to play ;-)

Jim, GI1CET
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: pmcouto on May 07, 2016, 12:09:33 pm
Hi,

My board is missing U9…

Looking at the picture here https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg924815/#msg924815 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg924815/#msg924815)
the marking on that little 5 pin SMD IC seems to be 10CB, 10C8 or 1DCB.

Could you please take a look at your boards and let me know the correct SMD marking on this IC?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on May 07, 2016, 12:50:25 pm
the marking on that little 5 pin SMD IC seems to be 10CB, 10C8 or 1DCB.

I sent that board back but I had another picture which I think shows 19CB. The one on the board I have here says AAAV.


(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=223035;image)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 07, 2016, 06:20:05 pm
pmcouto, in the end of the day I will see my board what is there.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on May 08, 2016, 10:18:15 am
Whereabouts on the board is U9 and I will check mine if it helps. Mine arrived complete and working.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kutte on May 09, 2016, 07:42:09 am
if you want some monitoring software running under windows, here it is:
http://www.romahn.info/symmetricom/Z38SY.ZIP (http://www.romahn.info/symmetricom/Z38SY.ZIP)
I've patched Ulrich Bangert's famous Z38XX to at least partially work with our Symmetricom UCCM-P.
For use first set the right "parameters" i.e. your com-port and hit ok.
Try the various functions under the "view" tab.
Kutte

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on May 09, 2016, 07:56:27 am
Slick, will have to give it a try. Miss the Lady Heather program.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: SHF on May 09, 2016, 11:36:59 am
if you want some monitoring software running under windows, here it is:
http://www.romahn.info/symmetricom/Z38SY.ZIP (http://www.romahn.info/symmetricom/Z38SY.ZIP)
I've patched Ulrich Bangert's famous Z38XX to at least partially work with our Symmetricom UCCM-P.
For use first set the right "parameters" i.e. your com-port and hit ok.
Try the various functions under the "view" tab.
Kutte
Hallo Kutte super Programm  :-+ :-+ :-+ :-+, vielen Dank hier für das posten !!!
Gruß Dieter
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on May 09, 2016, 02:53:55 pm
I sent that board back but I had another picture which I think shows 19CB. The one on the board I have here says AAAV.
Can confirm - 19CB on mine.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on May 09, 2016, 09:15:10 pm
if you want some monitoring software running under windows, here it is:
http://www.romahn.info/symmetricom/Z38SY.ZIP (http://www.romahn.info/symmetricom/Z38SY.ZIP)
I've patched Ulrich Bangert's famous Z38XX to at least partially work with our Symmetricom UCCM-P.
For use first set the right "parameters" i.e. your com-port and hit ok.
Try the various functions under the "view" tab.
Kutte
This is great! I assume by patched you used a hex editor to fix some strings vs compiling unobtanium source code?

I had just started writing something similar in C#.NET too...

Unfortunately the main PPS TI & EFC window doesn't update, and the Time Stability and "Nixie" Clock are greyed out too :( Looking at the debug log the EFC values are being queried and coming back with sensible values ok. Is there an obvious reason why these don't work other than the great difficulty in reverse engineering the original?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on May 09, 2016, 10:19:50 pm
You can also adjust the RS232 header to a different baud rate by using one of the two and select your baud rate.

SYSTem:COMMunication:SERial1:BAUD 9600|19200|38400|57600
or
SYSTem:COMMunication:SERial2:BAUD 9600|19200|38400|57600

I think it's the second one.

It is the SER2 that is the RS232 header.

Quote
Just a note your settings won't stick after a reboot, although I think the following may store the setting, just never tried it

SYSTem:COMMunication:SERial1:PRESet
SYSTem:COMMunication:SERial2:PRESet

Nope. These restore to factory default 57600,8,N,1

How do I know this? Because for some reason I get lots of line noise at 57600 baud (reminds me of my 1200 baud dial up modem days!). I use SYST:COMM:SER2:BAUD 19200 and all is ok but of course I have to reconnect after issuing that command.

This is possibly a fault of my cheap-ass CH340 USB/RS232 adapter.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kutte on May 10, 2016, 07:35:44 am
This is great! I assume by patched you used a hex editor to fix some strings vs compiling unobtanium source code?

I had just started writing something similar in C#.NET too...

Unfortunately the main PPS TI & EFC window doesn't update, and the Time Stability and "Nixie" Clock are greyed out too :( Looking at the debug log the EFC values are being queried and coming back with sensible values ok. Is there an obvious reason why these don't work other than the great difficulty in reverse engineering the original?

hi Macbeth,
I've made similar patches for my Lucent KS-24361 GPSDO and that worked in all aspects you are missing now. But the Symmetricom UCCM's command set differs in too many aspects from the original Z38xx command sets, so I could not put to work more than what is available. And yes, you are right, the sources of Ulrich's Z38xx are unobtainium. If anyone wants more functionality he (she) is free to do more reverse engineering and should tell us about any success.
Kutte
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kutte on May 10, 2016, 07:48:44 am
Stability and "Nixie" Clock are greyed out too :( Looking at the debug log the EFC values are being queried and coming back with sensible values ok. Is there an obvious reason why these don't work other than the great difficulty in reverse engineering the original?

I am missing that information too. The reason seems to be, that the Symmetricom does not deliver the appropriate timing data and additionally always appends an unwanted "Command Complete" string to any command given.

I did also not succeed to put time/date date into the Symmetricom to speed up satellite aquisition.
GPS:INITial:DATE 2016,1,29   // does not work (legal syntax but no effect)
GPS:INITial:TIME 23:59:01   // does not work (legal syntax but no effect)
GPS:INITial:POSition N,+52,+etc,E,+13,+etc // works ok
Kutte

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: deepskyridge on May 10, 2016, 06:36:41 pm
I am thinking of picking up one of these, do you guys have any documentation ?

I don't want to read all 20 pages of this thread.

Thanks
Gary
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ghulands on May 10, 2016, 08:38:39 pm
I am thinking of picking up one of these, do you guys have any documentation ?

I don't want to read all 20 pages of this thread.

Thanks
Gary

Click the All next to the page numbers, then it's only a single page!  :-DD
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on May 10, 2016, 09:14:02 pm
I am thinking of picking up one of these, do you guys have any documentation ?

I don't want to read all 20 pages of this thread.

Thanks
Gary

Maybe, unlike all of us, you can find the official manuals and datasheets? - I believe Penguin published a compendium but I haven't found much more than a book cover teaser myself...

(http://i.imgur.com/opraIT9.png?1)

I've rifled through dusty old bookshops high and low, but to no avail... I did find "Fly Fishing by J.R. Hartley" though  :-+
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 12, 2016, 08:26:04 pm
I found everything I needed, including links to various bits of documentation in the thread.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 12, 2016, 09:05:11 pm
+1 for that.

But it requires time to read. 

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 13, 2016, 01:08:49 pm
I'm a bit out of my depth here... but... after fiddling with some R values I seem to have a good output from the LT6551 (wow it was small).

Firstly I tried driving a 50R but this seemed to be a bit much for the output of the UCCM-P so I upped this by adding a 67R I had lying around giving around 120R and now I am seeing sufficient output on the LT6551 side (around 3V pp) after fixed x2 gain....

For bias I used a 5k4 and 1k5 I had lying around.

I wish I had made a PCB... now to wire up some outputs and see if it can drive the SDG1025 and Racal-Dana 1999 Counter...

I have 4 outputs.   :)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 13, 2016, 04:47:03 pm
I just received what claims to be a 240V to 6V 2A power adapter from China....

When I power the UCCM-P and other bits I get the same behaviour as I do with my bench supply... i.e. during the 5-10 min OCXO warm up phase I get a whining noise and the voltage dips to such a level that the Arduino etc brown out until the OCXO is warm and then everything is good.

How are people powering their gadgets?  Do I need to split the supplies?  One for UCCM-P, another for the rest?

Thanks in advance
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Electro Fan on May 13, 2016, 06:06:25 pm
I have not found or seen any official documentation for this board or the Trimble equivalents.(you can google for Trimble 63090 or 73090)
You can enable a once per second string but it is hex data string, not NMEA data.

As Brainbox mentioned the 4 mounting holes are not all ground - one of them is connected to the 5 volt regulator.

The M-act button does manually enable the 10 MHz output even if no GPS lock has been achieved. In the case of the my Trimble which has been running for months constantly it is very accurate in the short term from a cold start. With no GPS connected after the oven is warm it is currently within 4 mHz of proper 10 MHz. So if you had to take the unit out of the lab and just needed a quick reference it would do quite nicely even without GPS lock.

Some questions about M-act and GPSDOs in general:

When you press the M-act button does it output the 10 MHz signal continuously (until you press the button again), or does it output the 10 MHz signal only while you hold the button down?

If you don't use the antenna and you are happy being within 4 mHz of properly 10 MHz (I presume that is within in 4 milliHertz), can the system operate in this reduced accuracy mode indefinitely?  (For example if you don't have a good place to mount the antenna?)  Or is this reduced accuracy mode only available after you have initially established a GPS signal with the antenna?

Does a GPSDO antenna need to be outside with line of sight or can it be outside without line of sight, or inside with line of sight, or inside without line of sight?

Sorry for asking this (I know it's been discussed in other threads but I don't recall the conclusion), but is it better to use a GPSDO 10 MHz sine wave or square wave for a clock input to test equipment (frequency counter, oscilloscope, spectrum analyzer, etc.)?  Same answer or different answer when providing a clock input for communications equipment (ham transceivers, etc.)?

Last question (for now), what is the purpose of the 1 PPS Output vs the 10 MHz Output?

Thanks!

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on May 14, 2016, 12:25:37 am
I have not found or seen any official documentation for this board or the Trimble equivalents.(you can google for Trimble 63090 or 73090)
You can enable a once per second string but it is hex data string, not NMEA data.

As Brainbox mentioned the 4 mounting holes are not all ground - one of them is connected to the 5 volt regulator.

The M-act button does manually enable the 10 MHz output even if no GPS lock has been achieved. In the case of the my Trimble which has been running for months constantly it is very accurate in the short term from a cold start. With no GPS connected after the oven is warm it is currently within 4 mHz of proper 10 MHz. So if you had to take the unit out of the lab and just needed a quick reference it would do quite nicely even without GPS lock.

Some questions about M-act and GPSDOs in general:

When you press the M-act button does it output the 10 MHz signal continuously (until you press the button again), or does it output the 10 MHz signal only while you hold the button down?

If you don't use the antenna and you are happy being within 4 mHz of properly 10 MHz (I presume that is within in 4 milliHertz), can the system operate in this reduced accuracy mode indefinitely?  (For example if you don't have a good place to mount the antenna?)  Or is this reduced accuracy mode only available after you have initially established a GPS signal with the antenna?

Does a GPSDO antenna need to be outside with line of sight or can it be outside without line of sight, or inside with line of sight, or inside without line of sight?

Sorry for asking this (I know it's been discussed in other threads but I don't recall the conclusion), but is it better to use a GPSDO 10 MHz sine wave or square wave for a clock input to test equipment (frequency counter, oscilloscope, spectrum analyzer, etc.)?  Same answer or different answer when providing a clock input for communications equipment (ham transceivers, etc.)?

Last question (for now), what is the purpose of the 1 PPS Output vs the 10 MHz Output?

Thanks!

Hi

The OCXO has an unknown aging spec (could be 1 ppb / day). It also has an unknown retrace spec (could be 1 ppb over 24 hours). What is the temperature stability? Again, who knows. Warmup  ... orientation .... voltage .... who knows. If it holds 10 ppb for a week without the antenna, it's doing ok.

(1 Hz at 10 MHz is 100 ppb ...).

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Electro Fan on May 14, 2016, 05:54:23 am
I have not found or seen any official documentation for this board or the Trimble equivalents.(you can google for Trimble 63090 or 73090)
You can enable a once per second string but it is hex data string, not NMEA data.

As Brainbox mentioned the 4 mounting holes are not all ground - one of them is connected to the 5 volt regulator.

The M-act button does manually enable the 10 MHz output even if no GPS lock has been achieved. In the case of the my Trimble which has been running for months constantly it is very accurate in the short term from a cold start. With no GPS connected after the oven is warm it is currently within 4 mHz of proper 10 MHz. So if you had to take the unit out of the lab and just needed a quick reference it would do quite nicely even without GPS lock.

Some questions about M-act and GPSDOs in general:

When you press the M-act button does it output the 10 MHz signal continuously (until you press the button again), or does it output the 10 MHz signal only while you hold the button down?

If you don't use the antenna and you are happy being within 4 mHz of properly 10 MHz (I presume that is within in 4 milliHertz), can the system operate in this reduced accuracy mode indefinitely?  (For example if you don't have a good place to mount the antenna?)  Or is this reduced accuracy mode only available after you have initially established a GPS signal with the antenna?

Does a GPSDO antenna need to be outside with line of sight or can it be outside without line of sight, or inside with line of sight, or inside without line of sight?

Sorry for asking this (I know it's been discussed in other threads but I don't recall the conclusion), but is it better to use a GPSDO 10 MHz sine wave or square wave for a clock input to test equipment (frequency counter, oscilloscope, spectrum analyzer, etc.)?  Same answer or different answer when providing a clock input for communications equipment (ham transceivers, etc.)?

Last question (for now), what is the purpose of the 1 PPS Output vs the 10 MHz Output?

Thanks!

Hi

The OCXO has an unknown aging spec (could be 1 ppb / day). It also has an unknown retrace spec (could be 1 ppb over 24 hours). What is the temperature stability? Again, who knows. Warmup  ... orientation .... voltage .... who knows. If it holds 10 ppb for a week without the antenna, it's doing ok.

(1 Hz at 10 MHz is 100 ppb ...).

Bob

That's cool but I'm still hoping to get some answers to questions I asked ;)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on May 14, 2016, 06:55:13 am
That's cool but I'm still hoping to get some answers to questions I asked ;)

Sorry, but Bob's standard answer to questions like these is "It depends" - which is absolutely true!

Okay, maybe a few more details.....

Quote
If you don't use the antenna and you are happy being within 4 mHz of properly 10 MHz (I presume that is within in 4 milliHertz), can the system operate in this reduced accuracy mode indefinitely?  (For example if you don't have a good place to mount the antenna?)  Or is this reduced accuracy mode only available after you have initially established a GPS signal with the antenna?

That depends.  ;)  If you're using a surplus GPSDO, you don't know what the design criteria were.  Some GPSDOs take a few weeks(?) to learn how the OCXO ages.  After that, if they lose the GPS signal, they'll nudge the OCXO along to try to compensate for the drift.  Some aren't so smart.  The only way to determine how a particular type of GPSDO will react is to try it.

Quote
Does a GPSDO antenna need to be outside with line of sight or can it be outside without line of sight, or inside with line of sight, or inside without line of sight?

That depends.   ;D I don't know where you are, but, in general, you need some level of visibility towards the equator.  Obviously, outside with clear sky is better.  Newer GPSDOs have more sensitive receivers that can often work quite happily through a standard plywood and shingle roof.  The antenna also makes a difference.  A timing grade antenna has lots of gain and better filtering to help give good signals under challenging conditions.  Often they give good enough signal strength that an old, slightly deaf GPSDO works as well as a newer, more sensitive unit.  Don't get dazzled by the higher number of channels in the newer receivers.  Some of the best GPSDOs around only have a six channel receiver.

Quote
Sorry for asking this (I know it's been discussed in other threads but I don't recall the conclusion), but is it better to use a GPSDO 10 MHz sine wave or square wave for a clock input to test equipment (frequency counter, oscilloscope, spectrum analyzer, etc.)?  Same answer or different answer when providing a clock input for communications equipment (ham transceivers, etc.)?

That depends.   >:D  (I'm enjoying this way too much!) I've found that lots of equipment doesn't properly specify the external standard input.  They might specify maximum voltage, but sometimes not impedance and often, don't mention waveshape or frequency tolerance at all.  Using a GPSDO as an external reference for communications equipment is even more of a crapshoot.  If the equipment multiplies the reference up to a higher RF frequency, you probably need a really clean reference with very low phase noise.  GPSDOs almost never provide a signal that's clean enough.  You may need some kind of clean-up oscillator that's phase-locked to the GPSDO output to get a clean enough signal.

Quote
Last question (for now), what is the purpose of the 1 PPS Output vs the 10 MHz Output?

It varies.  :-DD  Some systems use the 10 MHz as the primary system clock.  There could be a multiplier or PLL to boost the frequency.  The 1 PPS might be used as an time-of-day / elapsed time sort of thing.  They could also use the 1 PPS with a phase-lock loop to lock the system's internal oscillator to the GPSDO.

Bottom line on these surplus GPSDOs is that we really don't know how well they'll perform until somebody buys them and starts doing tests and measurements.  That's the way it will always be.  That's the value of a forum like this.  Everybody can share their test results and build a picture of how well multiple units work under multiple conditions.  The alternative is to pay many, many dollars and buy new units straight from the manufacturer.  Then you'll get a full set of specs and can ask the manufacturer all the questions you want.  But, even then, don't be surprised if you get a few blank looks.

Evil Ed  >:D


Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on May 14, 2016, 06:57:34 am
Some questions about M-act and GPSDOs in general:

When you press the M-act button does it output the 10 MHz signal continuously (until you press the button again), or does it output the 10 MHz signal only while you hold the button down?

If you don't use the antenna and you are happy being within 4 mHz of properly 10 MHz (I presume that is within in 4 milliHertz), can the system operate in this reduced accuracy mode indefinitely?  (For example if you don't have a good place to mount the antenna?)  Or is this reduced accuracy mode only available after you have initially established a GPS signal with the antenna?

Does a GPSDO antenna need to be outside with line of sight or can it be outside without line of sight, or inside with line of sight, or inside without line of sight?

Sorry for asking this (I know it's been discussed in other threads but I don't recall the conclusion), but is it better to use a GPSDO 10 MHz sine wave or square wave for a clock input to test equipment (frequency counter, oscilloscope, spectrum analyzer, etc.)?  Same answer or different answer when providing a clock input for communications equipment (ham transceivers, etc.)?

Last question (for now), what is the purpose of the 1 PPS Output vs the 10 MHz Output?

Thanks!
1) In the thread somewhere.
2) should stay in holdover permanently. Then you rely on the aging rates of the ocxo. Which will need to be factored in.
3) My antenna is in my window, it works.
4) depends on the gear. Some doesn't care about the shape.
5) You lock oscillators to the 10Mhz easier. The 1pps is almost a universal gps output.  Often ised for clock(time) timing
The ocxo is most likely a Rakon ROX5242T2
http://www.rakon.com/products/families/download/file?fid=39.145 (http://www.rakon.com/products/families/download/file?fid=39.145)
Edit: I see ED beat me to posting.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on May 14, 2016, 07:36:52 am
in general, you need some level of visibility towards the equator.

 :-//
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 14, 2016, 09:49:31 am
When you press the M-act button does it output the 10 MHz signal continuously (until you press the button again), or does it output the 10 MHz signal only while you hold the button down?
Never tried it but I believe a previous poster (try reading the thread  :-DD) said it goes into a mode with odd flashing but outputs the undisciplined frequency (and you don't need to keep holding the button).
If you don't use the antenna and you are happy being within 4 mHz of properly 10 MHz (I presume that is within in 4 milliHertz), can the system operate in this reduced accuracy mode indefinitely?  (For example if you don't have a good place to mount the antenna?)  Or is this reduced accuracy mode only available after you have initially established a GPS signal with the antenna?
That's more than one question.  If you don't have an antenna then you don't have a GPSDO you have a OXCO with a small amount of disciplining logic based on prior measurement, all bets are off with respect to accuracy if the device has been out of reception for more than its holdover specification which is likely to be a relatively short period of the time.
Does a GPSDO antenna need to be outside with line of sight or can it be outside without line of sight, or inside with line of sight, or inside without line of sight?
The more satellites you have line of sight to the better the solution since it allows more of the errors (ionospheric delay etc) to be minimised.  Ideally you need line of sight since this will reduce error due to multipath and maximises likely observable satellites.  Solving for position requires at least 4 satellites (3D worth of position and 1D worth of time), solving for time requires less once position is known (1 might do) although as before the more satellites you have the more you can eliminate residual error and hence get a better estimate for a local clock.  In practical terms you need access to some sky but perhaps through a window would do.
Sorry for asking this (I know it's been discussed in other threads but I don't recall the conclusion), but is it better to use a GPSDO 10 MHz sine wave or square wave for a clock input to test equipment (frequency counter, oscilloscope, spectrum analyzer, etc.)?  Same answer or different answer when providing a clock input for communications equipment (ham transceivers, etc.)?
A square wave is a mix of many sine waves at different frequencies/amplitudes according to Mr Fourier.  (see Youtube/google if you need more info).  Sine wave is your friend for a continuous frequency, if you want something to tell you the occurrence of an event you will need something with a discontinuity like a pulse with the nasty harmonics that brings.
Last question (for now), what is the purpose of the 1 PPS Output vs the 10 MHz Output?
It drives things that need a 1Hz pulse... e.g. my Raspberry Pi based NTPd.
Thanks!
You're welcome!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on May 14, 2016, 04:48:27 pm
in general, you need some level of visibility towards the equator.

 :-//

Okay, maybe that was a bit extreme.

If you live near the equator, it doesn't matter what direction you look, you'll see lots of GPS satellites.  As you move further from the equator, you'll find that more birds are visible towards the equator than away from it.  If you're further than north or south 60 degrees, all satellites will be towards the equator.  So an antenna location that has good visibility towards the equator will maximize the number of satellites that you can see.

Another aspect of antenna location is geometry.  For example, in the northern hemisphere, east and south visibility would be better than east and west.  East and south would give you better triangulation to determine your position.  Bad geometry causes uncertainty and jitter in your calculated position.  Position jitter causes timing jitter.  In GPS terminology, geometry is called Dilution of Precision (DOP).  They break it down into TDOP (time), HDOP (horizontal), VDOP (vertical) and PDOP (position).  Smaller DOP values are better.

Ed
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on May 14, 2016, 06:07:52 pm
If you're further than north or south 60 degrees, all satellites will be towards the equator.  So an antenna location that has good visibility towards the equator will maximize the number of satellites that you can see.

Somehow I assumed that the orbits where spread evenly around earth but indeed, nothing above 60o.
That shows once more that you are never too old to learn.

Thanks Ed.

(http://freegeographytools.com/wp-content/uploads/2007/05/world-projection.gif)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on May 16, 2016, 07:59:20 am
if you want some monitoring software running under windows, here it is:
http://www.romahn.info/symmetricom/Z38SY.ZIP (http://www.romahn.info/symmetricom/Z38SY.ZIP)
I've patched Ulrich Bangert's famous Z38XX to at least partially work with our Symmetricom UCCM-P.
For use first set the right "parameters" i.e. your com-port and hit ok.
Try the various functions under the "view" tab.
Kutte
Hallo Kutte super Programm  :-+ :-+ :-+ :-+, vielen Dank hier für das posten !!!
Gruß Dieter

I wandered over to the website for the programmer. Sadly it looks like he passed away a couple years ago.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on May 16, 2016, 08:37:25 pm
if you want some monitoring software running under windows, here it is:
http://www.romahn.info/symmetricom/Z38SY.ZIP (http://www.romahn.info/symmetricom/Z38SY.ZIP)
I've patched Ulrich Bangert's famous Z38XX to at least partially work with our Symmetricom UCCM-P.
For use first set the right "parameters" i.e. your com-port and hit ok.
Try the various functions under the "view" tab.
Kutte
Hallo Kutte super Programm  :-+ :-+ :-+ :-+, vielen Dank hier für das posten !!!
Gruß Dieter

I wandered over to the website for the programmer. Sadly it looks like he passed away a couple years ago.

Hi

There has been an effort to continue Ulrich's work. It's not super active.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on May 16, 2016, 11:22:57 pm
Hi

There has been an effort to continue Ulrich's work. It's not super active.

Bob
Passed away far too early. He also did the excellent EZGPIB, which is just as tiny and completely bloatware and installer-less as Z38XX.

In order to continue then the source-code must be out there? A complete re-write would be easier than reverse engineering.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on May 16, 2016, 11:30:49 pm
Hi

There has been an effort to continue Ulrich's work. It's not super active.

Bob
Passed away far too early. He also did the excellent EZGPIB, which is just as tiny and completely bloatware and installer-less as Z38XX.

In order to continue then the source-code must be out there? A complete re-write would be easier than reverse engineering.


Hi

Apparently a neighbor / friend has access to the source code and has issued one or two minor patched versions. Based on a lot of correspondence back when the code was being developed -- there was a lot of guessing going on. Much of the protocol information was incomplete. The code was written so the outputs looked sensible on the GPSDO's available at that time. I suspect that without the notes on how this or that was come up with, the source code might not be very useful.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on May 17, 2016, 12:07:45 am
Apparently a neighbor / friend has access to the source code and has issued one or two minor patched versions. Based on a lot of correspondence back when the code was being developed -- there was a lot of guessing going on. Much of the protocol information was incomplete. The code was written so the outputs looked sensible on the GPSDO's available at that time. I suspect that without the notes on how this or that was come up with, the source code might not be very useful.
I've always been of the opinion that ultimately the code IS the documentation. Merciless refactoring is also not a problem. (That was the political term used to get a pointy head project manager agree to a complete rewrite without knowing it. I think they have cottoned on by now!  :-DD ).

Any source-code is better than no source-code. That's why we have such a big thing about open source!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on May 18, 2016, 12:32:03 am
Apparently a neighbor / friend has access to the source code and has issued one or two minor patched versions. Based on a lot of correspondence back when the code was being developed -- there was a lot of guessing going on. Much of the protocol information was incomplete. The code was written so the outputs looked sensible on the GPSDO's available at that time. I suspect that without the notes on how this or that was come up with, the source code might not be very useful.
I've always been of the opinion that ultimately the code IS the documentation. Merciless refactoring is also not a problem. (That was the political term used to get a pointy head project manager agree to a complete rewrite without knowing it. I think they have cottoned on by now!  :-DD ).

Any source-code is better than no source-code. That's why we have such a big thing about open source!

Hi

Well the reason it's not open source is indeed the other side of open source ---- "look at the stupid stuff this guy did... ha,ha,ha ...."

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 18, 2016, 08:27:11 pm
Please help out a new player...

I have the output of the 10MHz and I want to feed this into my LT6551 which is fed with 3V3 and will give a gain of 2.  So I want to have a signal that is roughly 1V6 pp I will then bias it so it varies 0 to +1v6...

Observing the output of the UCCM-P when put into my Rigol which is high Z... I see approx 2V9 pp.

Into 50 Ohms this gets squashed to a dismal 520mV pp...

... into 67 Ohms I get 1V84

into 117 Ohms I get 2V28

into 78k Ohms I get pretty much the same as high Z... 2v8... 2v9 ish

I assume all this is trying to tell me something about the output impedance of the device... do I just pick a number around 60 ohms or is more thought required?

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on May 19, 2016, 12:13:04 am
Please help out a new player...

I have the output of the 10MHz and I want to feed this into my LT6551 which is fed with 3V3 and will give a gain of 2.  So I want to have a signal that is roughly 1V6 pp I will then bias it so it varies 0 to +1v6...

Observing the output of the UCCM-P when put into my Rigol which is high Z... I see approx 2V9 pp.

Into 50 Ohms this gets squashed to a dismal 520mV pp...

... into 67 Ohms I get 1V84

into 117 Ohms I get 2V28

into 78k Ohms I get pretty much the same as high Z... 2v8... 2v9 ish

I assume all this is trying to tell me something about the output impedance of the device... do I just pick a number around 60 ohms or is more thought required?

Hi

The output of the device likely goes through a filter. The filter tuning is set up to work at a specific load impedance (likely 50 ohms). Change the load impedance and you change the characteristics (cutoff, attenuation) of the filter.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on May 19, 2016, 05:32:16 am
All:

Would anyone know what the following output statements likely mean in terms of the 10MHZ output.

freq cor  = -5.122888e-09
phase cor = 2.000000e-11
gps phase = 2.333333e-09


Code: [Select]
UCCM-P > diagnostic:loop?
-------------------------------------------------------------------------------
5/18/2016 05:19:02
-------------------------------------------------------------------------------

   LOS      MEAS       NCO STATUS WEIGHT PBUC FBUC DBUC LBUC IBUC G  M TC
-------------------------------------------------------------------------------
 0:  1  0.000e+00  0.000e+00 0x07AC   X   700  700    0    0    2  2  4 29
 1:  1  0.000e+00  0.000e+00 0x068C   X   700  700    0    0    0  2 14 226
GPS: 0  2.524e-09 -5.123e-09 0x0000   1  ---- 1000 1000 ---- ----  3  6 31
-------------------------------------------------------------------------------
freq cor  = -5.122888e-09
phase cor = 2.000000e-11
gps phase = 2.333333e-09
temp cor  = -8.082023e-11
Command Complete

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 19, 2016, 07:21:24 am
The output of the device likely goes through a filter. The filter tuning is set up to work at a specific load impedance (likely 50 ohms). Change the load impedance and you change the characteristics (cutoff, attenuation) of the filter.
Hm... OK but at 50 Ohms it is a very small signal.  I don't think I have the tools to take this much further... presumably I would need a spectrum analyser and then look at the spectrum at different output loads.  I guess I'm going to pick 62 Ohms and see what happens.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 19, 2016, 07:47:44 am
freq cor  = -5.122888e-09
phase cor = 2.000000e-11
gps phase = 2.333333e-09
Of all the numbers in diagnostic:loop? there seem to be only six that change.
On the GPS line of the table two numbers 2.524e-09 -5.123e-09 here change.  The second seems to be a rounded version of freq_cor.
Then we have freq cor, phase cor, gps phase, temp cor.

phase cor & gps phase are only calculated when a GPS solution for PPS is available.

Over time the numbers seem relatively stable... so my guess would be that they are simply the adjustment of your aged temperature sensitive OCXO discplined by frequency and temperature to the GPS signal over time using presumably some form of PID/Kalman filtering.

EFC might be another thing to look at... I haven't had the time myself.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 19, 2016, 09:05:27 am
NivagSwerdna, if all you want is two outputs why you don´t try an Wilkinson divider like this one < http://www.jrmiller.demon.co.uk/projects/ministd/wilk.pdf (http://www.jrmiller.demon.co.uk/projects/ministd/wilk.pdf) > very simple to do and it's for 10MHz.

Or look at this one < http://www.kolumbus.fi/~ks9292/10MHz_Rubidium_standard/Dist_amp_sch.pdf (http://www.kolumbus.fi/~ks9292/10MHz_Rubidium_standard/Dist_amp_sch.pdf) >
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 19, 2016, 07:15:07 pm
Or look at this one < http://www.kolumbus.fi/~ks9292/10MHz_Rubidium_standard/Dist_amp_sch.pdf (http://www.kolumbus.fi/~ks9292/10MHz_Rubidium_standard/Dist_amp_sch.pdf) >
;) That one has 100R at the start
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 19, 2016, 08:42:13 pm
Yep, I only saw it now, it was one quick search.

G4HUP does one with 4 out's, or with 8 ways, I think that kit price is £51.

Or you can use one video amplifier box from ebay, look at Gerry Sweeney web.

http://gerrysweeney.com/build-a-10mhz-rubidium-frequency-standard-and-signal-distribution-amp-for-my-lab/ (http://gerrysweeney.com/build-a-10mhz-rubidium-frequency-standard-and-signal-distribution-amp-for-my-lab/)
http://gerrysweeney.com/10mhz-rubidium-frequency-standard-and-signal-distribution-amp-follow-up/ (http://gerrysweeney.com/10mhz-rubidium-frequency-standard-and-signal-distribution-amp-follow-up/)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 19, 2016, 09:14:43 pm
I'm pretty close and I want it to fit in my box... PCB on the way.... just need to tweak a few values to bias it right....
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 19, 2016, 10:03:45 pm
Still waiting for the rest of my stuff to arrive, antenna, cables, raspberry 3, and other small stuff.
Then put it all together to see the size of the box, with the 8 way distribution amplifier.

I'm thinking to power the UCCM separate from the raspberry and arduino.

One entrance for +12V 8A, then divided in +5V 3A for UCCM, +5V 1A to arduino, +5V 2A for raspberry.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on May 19, 2016, 11:41:22 pm
You don't think a close to 100W supply is a little bit overkill?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on May 20, 2016, 12:17:26 am
I figured 5v at 5A would easily be sufficient for everything. Thinking about it a 15W 5V supply would be the least power needed. Use a precision comparator or timer to turn on a relay powering the digital stuff. After either about 10 minutes, or when the shunt voltage drops.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 20, 2016, 08:55:48 am
Very interested to hear about power supply solutions... I bought a 6V 2A cheapo adapter from EBAY... gives me the same brown out behaviour I get with my bench supply until the OCXO is warm but after that everything stabilises and I get around 800mA constant from my bits and pieces.

The early start brown-out isn't very nice... especially to the Rpi.

I guess the sensible solution is to provide 12V and regulate down for the controllers?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 20, 2016, 10:33:46 am
It can be overkill, I've to see what I've around here, but I was talking about taking out the +5V from the +12V 8A supply.

My thinking is provide one Input for 12V and then divided by the UCCM, Arduino and Raspberry.

UCCM - 5V 2.5A for start on OCXO warmup
Arduino - 5V 500mA with TFT ???
Raspberry 3 - 5V 1A ???

This should be around 12V 4A or maybe 3A ???

+12V 4A to one LT1085 feeding the UCCM, picking up the same +12V feeding one LM7805 to the Arduino, and another to the Raspberry.

Maybe one comparator, that compares the dropout of the OCXO warmup from 3A to 800mA, and then close one reed relay that will feed the Arduino and Raspberry.
In this approach there will be no display when power up, but since the GPSDO is to be run in contínuos mode, and even if it be unplug from time to time, no problem in staying 5 minutes without display.
 
 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on May 21, 2016, 12:37:54 am
It can be overkill, I've to see what I've around here, but I was talking about taking out the +5V from the +12V 8A supply.

My thinking is provide one Input for 12V and then divided by the UCCM, Arduino and Raspberry.

UCCM - 5V 2.5A for start on OCXO warmup
Arduino - 5V 500mA with TFT ???
Raspberry 3 - 5V 1A ???

This should be around 12V 4A or maybe 3A ???

+12V 4A to one LT1085 feeding the UCCM, picking up the same +12V feeding one LM7805 to the Arduino, and another to the Raspberry.


Keep in mind, if you are using a 12v supply and are using linear regulators to get 5v, you will be dissipating more power in the regulators than in the devices themselves. 7v * the current draw for each device.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on May 21, 2016, 12:55:01 am
Wow. This is a great thread! I've learned a lot of info about the Symmetricom GPSDO here. Mine came with the oil on the board and a few damaged caps. All of which were repairable. One thing I noticed is that it really is sensitive to having a LOS view to the satellites. I had my GPS antenna (A lucent antenna with 26db of gain) on a pole in some trees. It had a terrible time even getting a fix. It took hours. I moved the antenna to the unused chimney on the roof of the house and it made a world of difference. Before it would only track about 4 or 5 satellites and they were never stable. Now it tracks about 8-10 on average and they are stable. So, I had mine running for a day or so and I got an error that the frequency control was at the upper limit. The Fc to the OCXO was pegged at 5.1v. I also was getting low OCXO current warnings. I removed the OCXO and poped the cover off and reflowed all of the connections on the lower board. It's a single oven if anyone wants to know. I put it back together and it ran for a few days and then I got the same error. So, I happened to see an exact replacement OCXO on Ebay: 222113598831. I ordered one because is was at a reasonable price and it was not overseas. Well, the "new" oscillator arrived a few days ago and it was defective. I sent it back and got a refund. I wasn't going to take another chance on a replacement fearing that maybe they all came from a bad lot. I'm wondering if anyone else has had trouble with the Symmetricom OCXOs? I bought a used Oscilloquartz OCXO and hopefully it will arrive next week and will be a drop in replacement.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on May 21, 2016, 01:10:59 am
Wow. This is a great thread! I've learned a lot of info about the Symmetricom GPSDO here. Mine came with the oil on the board and a few damaged caps. All of which were repairable. One thing I noticed is that it really is sensitive to having a LOS view to the satellites. I had my GPS antenna (A lucent antenna with 26db of gain) on a pole in some trees. It had a terrible time even getting a fix. It took hours. I moved the antenna to the unused chimney on the roof of the house and it made a world of difference. Before it would only track about 4 or 5 satellites and they were never stable. Now it tracks about 8-10 on average and they are stable. So, I had mine running for a day or so and I got an error that the frequency control was at the upper limit. The Fc to the OCXO was pegged at 5.1v. I also was getting low OCXO current warnings. I removed the OCXO and poped the cover off and reflowed all of the connections on the lower board. It's a single oven if anyone wants to know. I put it back together and it ran for a few days and then I got the same error. So, I happened to see an exact replacement OCXO on Ebay: 222113598831. I ordered one because is was at a reasonable price and it was not overseas. Well, the "new" oscillator arrived a few days ago and it was defective. I sent it back and got a refund. I wasn't going to take another chance on a replacement fearing that maybe they all came from a bad lot. I'm wondering if anyone else has had trouble with the Symmetricom OCXOs? I bought a used Oscilloquartz OCXO and hopefully it will arrive next week and will be a drop in replacement.

Hi

All of the OCXO's you see for the most part are salvaged off boards in China. Every once in a while there is a "brand new" one that pops up. The other 99 batches are all salvage parts. They all go through a pretty brutal process getting them off of the boards. If you run a full test of the parts when you get them (including temperature, aging, and phase noise) it is rare to find even one in 40 that meet spec. With most batches it does not take a lot of testing to spot the failures, 10 out of 10 have an output < 0 dbm when the spec is +7 or some such thing. It's not the OCXO that is the issue as much as using a weed burning torch to pull them off the board. Tossing them into a 55 gallon drum from 10 feet away likely is not the best next step after they come off the board. Having the drum sit out in the rain until it fills with OCXO's seems to be the next phase.

Good Luck!

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 21, 2016, 07:16:18 pm
And the most damaged ones at the bottom of the barrel are taken by flyxy2015

DO NOT PURCHASE FROM flyxy2015.  I agree with others... he is a THIEF.  I ended up with nothing and paid the full amount.

(My working board came from waikeionline_uk)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on May 21, 2016, 08:29:26 pm
(My working board came from waikeionline_uk)

He sent me 2 damaged ones I returned, now he supposedly sent me "working" ones but I have to see it to believe it. Also, he refunded me $20 from my original payment to pay for the return. The tracking on the return shipment shows that he still did not pick them up (but that could be an error of course). Oh well, you get what you pay for I guess...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 22, 2016, 09:37:05 am
Also, he refunded me $20 from my original payment to pay for the return. The tracking on the return shipment shows that he still did not pick them up (but that could be an error of course). Oh well, you get what you pay for I guess...
That's where he got me... the tracking never showed completed so EBAY sided with him.  Returns don't work with some people.  He also timed is so it was too late to leave feedback.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 22, 2016, 09:46:51 am
I got mine from waikeionline_uk too, and the board work after 2 caps, and the GPS connector.
I'll probably get another board from him, after I finish this one.
About feedback, I only leave feedbacks after I receive the order and try it, only then I go there and leave the feedback.

Received Friday some more bits, still missing the antenna, cables and some connectors.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kutte on May 24, 2016, 09:13:27 am
I bought a used Oscilloquartz OCXO and hopefully it will arrive next week and will be a drop in replacement.
my Oscilloquartz OCXO 8663-XS did not work as an exchange although beeing compatible in its dimensions it is not with its Vref and Vefc.
Kutte
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kutte on May 24, 2016, 09:29:13 am
made some Adev measurements of my Symmetricom GPSDO.  Adev of GPS-locked GPSDO is very similar to ZigmundRat's (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-%28ocxo-furuno-receiver%29/msg890574/#msg890574 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-%28ocxo-furuno-receiver%29/msg890574/#msg890574)) measurement, see my blue curve. For reference I measured my Lucent KS-24361, see red curve under same conditions. And finally I measured the Symmetricom OCXO in "holdover-mode" (i.e. antenna input left open), see green curve. As you can see, the Symmetricom GPSDO is not optimal disciplined but the OCXO alone is one of the best I own. Please note: Adev-reference is always my Trimble Tunderbolt since I do not have any better.
Kutte
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 24, 2016, 12:51:58 pm
My first ever PCB!  Isn't she a beauty!  10MHz in and 4x 10MHz outputs, Pulse stretch and multiple PPS outputs and a TTL/RS232 level converter on the flip side.

10MHz in... via LT6551 gives 4x 10MHz out...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 24, 2016, 01:28:46 pm
Very nice board.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on May 24, 2016, 01:29:44 pm
Nice job, looks tiny.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on May 24, 2016, 08:07:04 pm
I bought a used Oscilloquartz OCXO and hopefully it will arrive next week and will be a drop in replacement.
my Oscilloquartz OCXO 8663-XS did not work as an exchange although beeing compatible in its dimensions it is not with its Vref and Vefc.
Kutte

Rats! I saw the Vref and Vefc were around 8v and 0-10v respectively. Did you use a different OCXO? Do you know if the Vref output is actually used?
I don't think it would be too difficult to scale them with a couple op-amps using the 12v as the supply. Or maybe a single shunt resistor for the Vref output since it has about a 1k impedance and then just a x2 op-amp for the Vefc.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on May 24, 2016, 09:21:30 pm
I bought a used Oscilloquartz OCXO and hopefully it will arrive next week and will be a drop in replacement.
my Oscilloquartz OCXO 8663-XS did not work as an exchange although beeing compatible in its dimensions it is not with its Vref and Vefc.
Kutte

Rats! I saw the Vref and Vefc were around 8v and 0-10v respectively. Did you use a different OCXO? Do you know if the Vref output is actually used?
I don't think it would be too difficult to scale them with a couple op-amps using the 12v as the supply. Or maybe a single shunt resistor for the Vref output since it has about a 1k impedance and then just a x2 op-amp for the Vefc.
Besides tuning voltages, you will also need to look into the tuning slope of the ocxo.  Positive vs negative ones.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kutte on May 25, 2016, 02:53:44 pm
Rats! I saw the Vref and Vefc were around 8v and 0-10v respectively. Did you use a different OCXO? Do you know if the Vref output is actually used?
I don't think it would be too difficult to scale them with a couple op-amps using the 12v as the supply. Or maybe a single shunt resistor for the Vref output since it has about a 1k impedance and then just a x2 op-amp for the Vefc.
a data sheet for the OSA 8663-XS you may find here:
http://www.2917.com/EBAY-images/DOCXO/8663.pdf (http://www.2917.com/EBAY-images/DOCXO/8663.pdf)
I did not try any further adaptations.
Kutte
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 29, 2016, 09:04:58 am
The dissipation of heat by the GPSDO is a bit of a problem... it is making my room a bit hot.

What material might be suitable to put around the OCXO to thermally isolate it?  (I have seen some odd foamy stuff in Rb standards before)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on May 29, 2016, 09:37:20 am
Some guys put some kind of foamy on all 4 sides of the OCXO, but from what I've read on the Time nuts list, this will make the OCXO incapable of heat regulation, because the heat would have no place to go, making the OCXO temp rise so the OCXO will lower the EFC to compensate, then it decompensating the OCXO.

Some guys put the foamy but leave about 3 to 4cm around the OCXO, but it will lead to the same result.

Try to read some of this on Time nuts list.

Still waiting for my antenna to show up here, it-s been in the customs for about 10 days, but the rest is here.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on May 29, 2016, 02:57:53 pm
Some guys put some kind of foamy on all 4 sides of the OCXO, but from what I've read on the Time nuts list, this will make the OCXO incapable of heat regulation, because the heat would have no place to go, making the OCXO temp rise so the OCXO will lower the EFC to compensate, then it decompensating the OCXO.

Some guys put the foamy but leave about 3 to 4cm around the OCXO, but it will lead to the same result.

Try to read some of this on Time nuts list.

Still waiting for my antenna to show up here, it-s been in the customs for about 10 days, but the rest is here.

Hi

The thermal gain of the heater in the OCXO is determined by the power in the heater times the thermal resistance from the heater to ambient. If you add insulation, you increase the thermal gain. A modern OCXO is "tweaked" for optimum gain at the factory. If you increase or decrease the gain, the unit will no longer be at the optimum setting.

The second issue is that there is only so much energy controlled by the heater. Stuff like the oscillator draw power regardless of the temperature. That means that the oven must always be some fixed amount above the upper ambient temperature. The classic term for this is "dead power" and thus "dead heat". In a typical design you may see 10C for this.

Next up is the fact that an economical crystal has a tolerance on it. You don't get every single one at exactly the same turn temperature. The tighter you spec them, the more you throw away. Net result is a typical tolerance of about 15 to 20C on the crystal temperature.

So, lots of variables. Lots of things to go wrong. Lots of "worked for you" / "failed for me". Unless you have the ability to do a full temperature run on the OCXO (say -20 to +70C), there is no real way to even know how much you degraded the device.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: rastro on May 30, 2016, 04:11:53 pm
I received a unit with L20 pulled up and damaged.   I need to find a replacement but its not clear what part is really needed.

This has was previously identified as a 5uH Inductor.  However after looking at the damaged part it seems like part has 4 separate pads and comprises what appears to be 2 separate coil winding.  If I were to see this part without knowing it's designation "L" I would think it was a transformer.

hi to all,
received my Symmetricom board yesterday. As to be exspected some damage could be seen. On the top side xtal y1 is missing, inductor L20 was ripped off. On the botton side capacitor C26 and resistor R83 were missing.
R83 could be easily identified as 103 (10kOhm), C26 is in neighbourhood of C27 which I measured as 1.2 uF. I put in 0.56 uF as a provisory measure.
Inductor L20 I measured as 5uH and replaced with a new one. ...
regards Goetz

I've attached some pictures showing the bottom of the damaged L20.  There appears to be a 3 turn winding between 2-pads sitting next to a larger double layer winding connecting to 2 pads on the other end.  So I can either find a replacement (ideal) or try and cobble together a repair (difficult).  Any further insight would be greatly appreciated.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: rastro on May 30, 2016, 04:18:24 pm
Location of L20.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on May 30, 2016, 06:53:51 pm
Also, he refunded me $20 from my original payment to pay for the return. The tracking on the return shipment shows that he still did not pick them up (but that could be an error of course). Oh well, you get what you pay for I guess...
That's where he got me... the tracking never showed completed so EBAY sided with him.  Returns don't work with some people.  He also timed is so it was too late to leave feedback.

The continuing story of waikeionline_us (not _uk but the same guy obviously)

Today I received his replacement shipment (to my surprise I must say).

Guess what, not 2 but 4 pcb's! But there is where the fun ends: 2 are missing the TXCO's, they are all damaged and cannibalized (push buttons, crystals, connectors, coils and caps).
On top of that he never picked up my return shipment so that also landed on my desk today. I wonder if I can get 2 working ones from the pile of rubbish  :--
I think I should ask PayPal for a refund of the rest of the payment (he already refunded $20 for the return shipment...) for the trouble I have to get at least something working.
And yes they where listed as working.

Moral of the story: don't buy anything from waikeionline_*

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=228909;image)

edit: Picture attached.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on May 31, 2016, 01:45:49 am
I think the seller has probably reached the bottom of the barrel (literally) of these units and selling off what he can. But you are right, best to stay away.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on May 31, 2016, 01:51:56 am
Does anyone know what these NMEA like commands are outputting

$PFEC,GPtps,160530053705,3,1,2,150701000000,00,17,160530015837,1899,106642
$PFEC,GPrrm,0,0,00,00,00,00,+000,+02

No doubt some custom Furuno/Symmetricom commands, but I can't seem to find anything out there that describes what they mean. Thinking the GPTPS may just by the term"tps" may be describing the 1pps output??

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on May 31, 2016, 06:51:49 am
The NMEA commands are described in the Furuno protocol spec.... it's linked somewhere earlier in this thread.

(I use $PFEC,GPtps for my NTPd interface see https://gitlab.com/NivagSwerdna/SymmetricomUCCMDisplay/blob/master/sketches/firsttft/nmea.cpp (https://gitlab.com/NivagSwerdna/SymmetricomUCCMDisplay/blob/master/sketches/firsttft/nmea.cpp) I create a synthetic $GPRMC from a $PFEC,GPtps)

http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Furuno/Furuno_GT8031_Protocol_Specification_Rev1.pdf (http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Furuno/Furuno_GT8031_Protocol_Specification_Rev1.pdf)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on May 31, 2016, 07:18:25 am
The NMEA commands are described in the Furuno protocol spec.... it's linked somewhere earlier in this thread.

(I use $PFEC,GPtps for my NTPd interface see https://gitlab.com/NivagSwerdna/SymmetricomUCCMDisplay/blob/master/sketches/firsttft/nmea.cpp. (https://gitlab.com/NivagSwerdna/SymmetricomUCCMDisplay/blob/master/sketches/firsttft/nmea.cpp.) I create a synthetic $GPRMC from a $PFEC,GPtps)

http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Furuno/Furuno_GT8031_Protocol_Specification_Rev1.pdf (http://www.ko4bb.com/getsimple/index.php?id=download&file=02_GPS_Timing/Furuno/Furuno_GT8031_Protocol_Specification_Rev1.pdf)

Excellent, thank you very much.

p.s. The period at the end of first link needs to be removed, otherwise link is broken.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kutte on June 01, 2016, 02:36:49 pm
Location of L20.
yes, it looks like a transformer, but it is not. I just put in a replacement inductor of 2.2uH onto the tabs next to R105 and this worked. Actual value does not seem to be critical.
Kutte
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Confucian on June 01, 2016, 07:40:15 pm
Hi All
Great thread, info overload. lol
My unit arrived today with oil and damage.
See below .  With values and actions suggested in this thread.
I have stolen shempe's picture to show location of damage (hope he dosnt mind)
GPS Ant Socket missing ------------ I will solder coax pigtail to Board.
RST & MACT switches both Broken ----------- Double Pole Momentary action -------- move to front panel of enclosure
C23 & 35 missing -------------- 100nf
C4 missing and pads ripped off ---------- 220uf 25v --------- need to scrape away green layer to discover tracks
U24 Missing   --------- Has anyone any Idea what U24 is and can you spot any deliberate mistakes above :-)
Thanks
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on June 01, 2016, 07:49:31 pm
U24 Missing   --------- Has anyone any Idea what U24 is

Z04, must be 1/6th of a ls04, inverter.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on June 01, 2016, 08:41:07 pm
Location of L20.
yes, it looks like a transformer, but it is not. I just put in a replacement inductor of 2.2uH onto the tabs next to R105 and this worked. Actual value does not seem to be critical.
Kutte
I think its a common mode choke with the winding with the red dot going across unpopulated R105 measuring 5.4uH and the lower winding isolated from the above. The lower winding on mine appears to be a dead short. In circuit measurements using a DER EE-5000. I suspect the short on the lower winding is deliberate and elsewhere on the PCB.

rastro, check your unpopulated L20 pads and if the lower measures a short then surely you could get away with merely turning the bad L20 upside down and soldering it back on ;)

ETA: Just checked your previous post with the 3 turn winding. That is so tiny it would show up short. Hmm...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 02, 2016, 01:20:06 am
(I use $PFEC,GPtps for my NTPd interface see https://gitlab.com/NivagSwerdna/SymmetricomUCCMDisplay/blob/master/sketches/firsttft/nmea.cpp (https://gitlab.com/NivagSwerdna/SymmetricomUCCMDisplay/blob/master/sketches/firsttft/nmea.cpp) I create a synthetic $GPRMC from a $PFEC,GPtps)

MacBeth
Had a look at your project and it looks quite impressive, are you able to share any screenshots of the TFT display with the project running.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: rastro on June 02, 2016, 01:22:28 am
Kutte & Macbeth,

Good information I'll probably use a 2-5uH inductor.  I don't think the original L20 could stand a round of soldering - plus the 2 pads are broken.

Thanks for the feedback.

-rastro
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 02, 2016, 07:17:48 am
are you able to share any screenshots of the TFT display with the project running.
There are some pictures earlier in the thread.. The display is really sweet... touch screen menus...
https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg911644/#msg911644 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg911644/#msg911644)
https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg934318/#msg934318 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg934318/#msg934318)
I'm just finishing off my 1:4 splitter (took me ages to get the LT6551 bias correct).
https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg947866/#msg947866 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg947866/#msg947866)
and may use the pulse stretcher that is also on that board to run the NTPd PPS rather than currently taking it off the Furuno
and then a bit of work on the software to add the ability to also interact via the USB at the same time (would be really good if we could find some pins for a 2nd comm port on the UCCM-P)...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Confucian on June 02, 2016, 02:40:15 pm
Has anyone any Idea what C4 is connected to ? I have pads missing, have scraped away at the green layer but can only find a broken track to one end of C6.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 02, 2016, 07:26:04 pm
See photo... one end attaches to a small nearby via and disappears downwards, the other end heads off to C6
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Confucian on June 02, 2016, 08:26:24 pm
See photo... one end attaches to a small nearby via and disappears downwards, the other end heads off to C6
Thank you for the Pics, looks like I may have to create my own "via" and connect to the other side of that one as not a lot of it left.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 02, 2016, 09:30:12 pm
Thank you for the Pics, looks like I may have to create my own "via" and connect to the other side of that one as not a lot of it left.
Once you find the other end you might find its just GND and that is available close by on the top side.  The daughter board is just a boost converter from 5V to 12V so C4 probably is just a smoothing capacitor on the output?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on June 03, 2016, 03:28:41 pm
I bought a used Oscilloquartz OCXO and hopefully it will arrive next week and will be a drop in replacement.
my Oscilloquartz OCXO 8663-XS did not work as an exchange although beeing compatible in its dimensions it is not with its Vref and Vefc.
Kutte

I finally received my Oscilloquartz 8663-XS yesterday. I measured the Vref and found it to be about 7.6v. So as an experiment, I applied 7.6v via a 3.3k resistor to the Vref pad on the Symmetricom board to see if it might get clamped to around 5v. It was about 7.6v so I figured there was no problem with the higher voltage input to the Vref pad. Next, I hooked up the OCXO via wires to the pads. I powered it up and noted that the Vtune voltage was about 4.7v and that it would go past 6.5v when hunting. It was about 2.7v in holdover mode with the original 5.1v Vref. The Fc tuning voltage for this OCXO is about 4.78v. I left it in circuit for a while and it appears to work perfectly. It locked up just fine. My thought is, the Vref output from the OCXO feeds a DAC and the DAC just scales the Vref value to tune the OCXO. Therefore even though the Vref voltage and tuning range are higher and broader than the original 0-5v, it doesn't matter since it is scaled by the DAC. the Kvco is about the same as the original. So it looks like this OCXO will work as a replacement, at least for my board. I got the OCXO from "flyingbest" on Ebay. I previously bought two Morion mv89a's from him and both of them worked good as well. I think he does a pretty good job of testing things he sells.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: rastro on June 03, 2016, 04:09:44 pm
Location of L20.
yes, it looks like a transformer, but it is not. I just put in a replacement inductor of 2.2uH onto the tabs next to R105 and this worked. Actual value does not seem to be critical.
Kutte

Fixed problem with damaged/lifted "L20".  I ended up soldering a 3.3uH surface mount inductor in the un-populated  R105 pads.  It is electrically the same as the L20 pads closest to the OSC/oven.  This is because the pads that go to L20 where lifted/marginal and the R105 is a better gap/distance for an SMD ferrite inductor that I used.  I ended up leaving the other 2 pads of L20 (closes to the edge of the PCB) un-populated since it essentially reads a short.

Picture attached prior to rework.

Thanks again for the help/advice.

-rastro

Anyway it's doing it's survey 20% complete.  So preliminary results are good.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 03, 2016, 09:08:23 pm
would be really good if we could find some pins for a 2nd comm port on the UCCM-P...
The more I think about this the more I think a 2nd output port doesn't exist.  The H8S/2317 has two serial interfaces (USART/UART/SCI whatever you want to call them).  It makes sense for one to talk to the GPS module and the other to talk to the outside world.  Happy for someone to prove me wrong.
The SCI are on Pin 8 TxD0, Pin 9 TxD1, Pin 10 RxD0 and Pin 11 RxD1 (counting pins anti-clockwise from the corner with the notch).
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on June 03, 2016, 11:25:10 pm
There is a second serial port on the Trimble version of these UCCMs, which I gather spits out a TOD (time of day) message in binary format every 2 seconds. This same feature is available in ASCII hex format on the normal serial channel by issuing the TOD ON command and TOD OFF to disable it.

I actually think this may be a simple way of getting NTP without tapping the 1PPS and the GPS module GPRS.

It bursts forward with its ASCII-HEX stream no matter what you are doing, like in the middle of a SYST:STAT? output, if the 2PS pulse hits it will just corrupt what you would normally expect with a sudden burst of data.

Thankfully the data packet appears consistent with a start byte, end byte plus white space/carriage return and fixed length within. It appears to have a CRC that I haven't worked out yet. However the GPS time and what I think is a UTC seconds offset byte (17) is clearly available in the data.

I've only been playing with RegExp and serial port interrupts to catch these quick and filter them out from normal serial stream.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on June 04, 2016, 05:13:35 am
Here are a couple images of the box I came up with. I may add a distribution amp eventually.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 04, 2016, 05:45:02 am
Here are a couple images of the box I came up with. I may add a distribution amp eventually.

Think I would keep the switching power supply as far away as possible from the GPSDO.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on June 04, 2016, 06:12:33 am
Here are a couple images of the box I came up with. I may add a distribution amp eventually.

Think I would keep the switching power supply as far away as possible from the GPSDO.

I didn't notice any noise pick up from the switcher and no degradation in satellite reception. I did add a common mode choke and caps on the 5v output which greatly reduced the switching ripple, etc. The power supply frame and chassis ground are single point grounded to the box. The switcher is a high quality Lambda supply and not some cheap made in China model and is fully enclosed. I looked at the 10MHz output with my HP8568A spectrum analyzer and there are no switching spurs or power supply harmonics visible, all the way down to a frequency span of 100Hz. So I don't think the power supply is a problem. On another note, I have a Racal Dana 1992 frequency counter. I measured the reference output and it has some hideous power supply side bands. It uses a 5MHz oven and has an x2 frequency multiplier board attached to the outside of the oven can. The x2 doubler uses two tunable inductors and these are coupling 60Hz harmonics from the power transformer and modulating the reference signal. It all depends...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 04, 2016, 08:46:18 am
Well, looks like you have certainly done your homework. Makes a big difference on the quality of the switching PS, yup have been there with the cheap Chinese ones.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on June 05, 2016, 01:09:28 am
Well, looks like you have certainly done your homework. Makes a big difference on the quality of the switching PS, yup have been there with the cheap Chinese ones.

Yea, I don't generally like switchers either but being that this thing is going to be on all the time, I decided to make it use as less power as possible. Thanks for the advice.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on June 05, 2016, 06:53:43 am
I've made a very nice discovery this evening. I know there have been several questions posted about a battery backup for the GPS data. Well, I was looking at the silk screen printing for J3. It reads 1:Rx, 2:Tx,3:BT,4:GD. 1,2 are of course the serial port. 4 is ground. BT.... Could it be short for battery? While the unit was on I measured about 3.2v on pin 3. I hooked up a power supply to pin3 and removed power on the unit. I waited a while and plugged it back in. It booted and I could see immediately that it had the GPS location and was in hold mode. Now for the bad news. With the unit powered off, it draws about 88ma from this pin and 0ma when its on. It could be that it keeps the GPS receiver alive with it. Definitely not just a CMOS memory backup. I'm not sure if its current limited so a super cap could be used on it.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 05, 2016, 08:24:31 am
Thanks for sharing the find. 88ma is a far amount for backupt, but would be ok for a short disconnect, like moving the unit or a brief power outage. I assume that there is protection circuitry built in and it is safe to just connect a 3.3v supply to it.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 05, 2016, 04:32:33 pm
re: Battery
https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg896521/#msg896521 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg896521/#msg896521)
and
https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg896506/#msg896506 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg896506/#msg896506)
From my experience you can reach PLL stability very rapidly by setting Hold position (assuming you know it from a previous survey)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 05, 2016, 08:20:00 pm
Quote
From my experience you can reach PLL stability very rapidly by setting Hold position (assuming you know it from a previous survey)

A method for quickly loading in the last known location.

https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg890574/#msg890574 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg890574/#msg890574)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on June 06, 2016, 02:48:23 am
Thanks for sharing the find. 88ma is a far amount for backupt, but would be ok for a short disconnect, like moving the unit or a brief power outage. I assume that there is protection circuitry built in and it is safe to just connect a 3.3v supply to it.

I didn't see any current draw when I connected a power source of 3.2v. One might be able to use a super cap with a resistor to charge it and then a Schottky diode in parallel with the resistor with the cathode pointing to the input pin for the discharge path.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on June 06, 2016, 05:29:08 am
Has anyone determined the leaning of the flashing led's. I always have a green 1pps(sort of close), a faster flashing green led. Unfortunstrly that one was replaced by a flashing red led after a few days.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: rastro on June 06, 2016, 01:32:04 pm
Problems getting board to lock into 10MHz GPS. 

History:
1. L20 was lifted so replaced with ~ 5uH SMD inductor
2. 12V power was loading down 5V supply and squealing - removed DC/DC daughter board and using separate 5V and 12V supplies.

What appears good:
1. Boots up and can communicate through 4-pin RS232 connector.
2. Completes site survey
3. Has 10MHz at output of OSC close to 10MHz.
4. Has output at 1PPS MCX connector.

Problem symptoms:
1. Will not feed through 10MHz clock after successful site survey.  Can force 10MHz output at MCX connector by toggling MACI button on PCB.
2. LED:GPSLock = 0  which probably means the system is not attempting to output the 10MHz clock.
3. OUTPut:STATe = UNLOCK and SYNChronization:FFOMerit = PLL unlocked ; Indicates problem with PPL for the 10MHz OSC ???
4. status shows #H/W FAIL ---------- [ LINK ] and #OPERATION ALARM --- [ EFC ],  Not sure what LINK is.  EFC possible "Electronic Frequency Correction"????
5. ALARm:HARDware? = NONE;  After all this I would think there would be a hardware alarm !!?? ???
6. Tried changing "satellite elevation mask" (GPS:SAT:TRAC:EMAN) to different values but made no effect.

So it appears the PLL is failing is related to EFC.  Is there some hidden setup I'm missing?  Any signals to check?

Code: [Select]
UCCM-P > SYST:STAT?
-------------------------------------------------------------------------------
090-03861-03   serial number W*********   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
XX Ref 8KHz 0: [LOS]                         
                                              TFOM     9             FFOM     3
                                              UCCM-P Status[OCXO WARM]
                                             
>> GPS: [phase: -1.96e-06, adjusting freq]   
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 5 ____   Not Tracking: 6 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      12:15:21     06 JUN 2016
  1  23 253   33    10   7 147                GPS      Synchronized to UTC
  3  38 313   34    22  62 292                ANT DLY  +0.000E+00
 14  36  75   38    23  11 293                Position ________________________
 16  23 176   31    25  11  38                MODE     Hold
 32  29  85   43    26  47 151               
                    31  60  27                LAT      N  **:**:**.***
                                              LON      W  **:**:**.***
                                              HGT              +***.** m  (MSL)
                                             
                                             
                                             
                                             
ELEV MASK 10 deg                             
-------------------------------------------------------------------------------

UCCM-P > status

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [OCXO Warm]
1-2. #Before ACTIVE STATUS ------------- [Wait for GPS]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [GPS]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Ref Analyzing]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [GPS > LINK]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
     #OPERATION ALARM --- [ EFC ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
Command Complete

UCCM-P > OUTPut:STATe?
UNLOCK
Command Complete

UCCM-P > LED:GPSLock?
0
Command Complete

UCCM-P > ALARm:HARDware?
NONE
Command Complete

UCCM-P > SYNChronization:FFOMerit?
PLL unlocked
Command Complete

UCCM-P > SYNChronization:TFOMerit?
Greater than 1E8 ns
Command Complete
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on June 06, 2016, 02:31:28 pm
1. L20 was lifted so replaced with ~ 5uH SMD inductor

Are you sure that L20 is a single inductor?

Edit: Just took one of a pcb and there is continuity both at the upper part ( R105) and the lower part, so it looks like there are 2 coils.
Even after taking off L20 there is still continuity on the lower part, but maybe it needs the coil?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on June 06, 2016, 05:10:12 pm
Hi is that inductor connected in any way to the crystal? if so you will need the exact value as the wrong value will change the resonant circuit frequency ?
Dave Browne 2E0DMB
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on June 06, 2016, 06:17:04 pm
Hi is that inductor connected in any way to the crystal? if so you will need the exact value as the wrong value will change the resonant circuit frequency ?
Dave Browne 2E0DMB

It looks like the crystal is directly connected to the LSI on the bottom, but I just found that the upper right of L20 (where the 5 from R105 is) goes directly to the RF output of the TXCO.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 07, 2016, 05:58:28 am
Quote
4. status shows #H/W FAIL ---------- [ LINK ] and #OPERATION ALARM --- [ EFC ],  Not sure what LINK i

I believe the H/WFAIL --- is normal, just means it is not sensing another unit. Think they were designed by the mfg to work with another, possible redundancy backup in the field I assume.

Your TFOM is way out, I note just under this statement it shows UCCM-P Status[OXCO warm], mine shows UCCM-P Status[ACTIVE] or UCCM-P Status[HOLDOVER] if it loses sight of enough birds or a antenna disconnect. Are you sure the unit is fully warmed up?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: rastro on June 07, 2016, 05:11:27 pm
Quote
4. status shows #H/W FAIL ---------- [ LINK ] and #OPERATION ALARM --- [ EFC ],  Not sure what LINK i

I believe the H/WFAIL --- is normal, just means it is not sensing another unit. Think they were designed by the mfg to work with another, possible redundancy backup in the field I assume.

Your TFOM is way out, I note just under this statement it shows UCCM-P Status[OXCO warm], mine shows UCCM-P Status[ACTIVE] or UCCM-P Status[HOLDOVER] if it loses sight of enough birds or a antenna disconnect. Are you sure the unit is fully warmed up?

What kind of values should I expect for a valid TFQM?
I think the OSC is warmed up - it's very hot to the touch. 
- If I measure its temperature what should I expect? 
- Is there status command I can use to see the OSC status?
- Also the 12V supply starts at about 500mA when cold then kicks down to lower current after several minutes.  It would appear the oven is regulating.  However I don't know what or how the systems controller makes a determination on when the oven temp is regulated at an working level.

I may try and kluge back on the L20 as some have suggested - I don't think it's gonna be easy because it has very fine wires. 
Has anyone successfully replaced L20 and have a working system i.e. PPL working?

-rastro
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on June 07, 2016, 05:58:23 pm
Ok, I just managed to measure L20 by sticking it on my bench with double sided tape  ;)
Both coils (upper and lower) measure 5uH, there's no connection between the 2 coils.

5uH ]|[ 5 uH

So either they used a left-over component in there or you will not get away with a single coil. The fact that one of the upper legs is connected to the RF output of the TCXO makes me believe that it is used to couple part of the output to the PLL? That would certainly explain why it doesn't lock with a single coil...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on June 07, 2016, 06:24:50 pm
Problems getting board to lock into 10MHz GPS. 

History:
1. L20 was lifted so replaced with ~ 5uH SMD inductor
2. 12V power was loading down 5V supply and squealing - removed DC/DC daughter board and using separate 5V and 12V supplies.

What appears good:
1. Boots up and can communicate through 4-pin RS232 connector.
2. Completes site survey
3. Has 10MHz at output of OSC close to 10MHz.
4. Has output at 1PPS MCX connector.

Problem symptoms:
1. Will not feed through 10MHz clock after successful site survey.  Can force 10MHz output at MCX connector by toggling MACI button on PCB.
2. LED:GPSLock = 0  which probably means the system is not attempting to output the 10MHz clock.
3. OUTPut:STATe = UNLOCK and SYNChronization:FFOMerit = PLL unlocked ; Indicates problem with PPL for the 10MHz OSC ???
4. status shows #H/W FAIL ---------- [ LINK ] and #OPERATION ALARM --- [ EFC ],  Not sure what LINK is.  EFC possible "Electronic Frequency Correction"????
5. ALARm:HARDware? = NONE;  After all this I would think there would be a hardware alarm !!?? ???
6. Tried changing "satellite elevation mask" (GPS:SAT:TRAC:EMAN) to different values but made no effect.

So it appears the PLL is failing is related to EFC.  Is there some hidden setup I'm missing?  Any signals to check?

Code: [Select]
UCCM-P > SYST:STAT?
-------------------------------------------------------------------------------
090-03861-03   serial number W*********   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
XX Ref 8KHz 0: [LOS]                         
                                              TFOM     9             FFOM     3
                                              UCCM-P Status[OCXO WARM]
                                             
>> GPS: [phase: -1.96e-06, adjusting freq]   
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 5 ____   Not Tracking: 6 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      12:15:21     06 JUN 2016
  1  23 253   33    10   7 147                GPS      Synchronized to UTC
  3  38 313   34    22  62 292                ANT DLY  +0.000E+00
 14  36  75   38    23  11 293                Position ________________________
 16  23 176   31    25  11  38                MODE     Hold
 32  29  85   43    26  47 151               
                    31  60  27                LAT      N  **:**:**.***
                                              LON      W  **:**:**.***
                                              HGT              +***.** m  (MSL)
                                             
                                             
                                             
                                             
ELEV MASK 10 deg                             
-------------------------------------------------------------------------------

UCCM-P > status

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [OCXO Warm]
1-2. #Before ACTIVE STATUS ------------- [Wait for GPS]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [GPS]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Ref Analyzing]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [GPS > LINK]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
     #OPERATION ALARM --- [ EFC ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
Command Complete

UCCM-P > OUTPut:STATe?
UNLOCK
Command Complete

UCCM-P > LED:GPSLock?
0
Command Complete

UCCM-P > ALARm:HARDware?
NONE
Command Complete

UCCM-P > SYNChronization:FFOMerit?
PLL unlocked
Command Complete

UCCM-P > SYNChronization:TFOMerit?
Greater than 1E8 ns
Command Complete

Check the output of the diagnostic log: DIAGnostic:LOG:READ:ALL?
It might tell you if the EFC is at the limits or if the OCXO current is too high/low. You can also measure the EFC voltage on the OCXO. Its the middle pin on the side that has 3 pins. Mine was about 2.7v when working and pegged at 5.1v when my OCXO was acting up. If the EFC voltage is towards the low end, the OCXO may be too warm. e.g. The temperature controller inside the OCXO failing.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: rastro on June 07, 2016, 10:57:56 pm
Check the output of the diagnostic log: DIAGnostic:LOG:READ:ALL?
It might tell you if the EFC is at the limits or if the OCXO current is too high/low. You can also measure the EFC voltage on the OCXO. Its the middle pin on the side that has 3 pins. Mine was about 2.7v when working and pegged at 5.1v when my OCXO was acting up. If the EFC voltage is towards the low end, the OCXO may be too warm. e.g. The temperature controller inside the OCXO failing.
Good idea:
Ran diagnostic log:  Most lines are "Time set to GPS" but did see EFC related error.
...Time set to GPS
.
.
L336:2016-06-07 20:52:08:Near EFC Sat Alarm : 0%  #appears to be when alarm gets set some time into the site survey.
...Time set to GPS
L366:2016-06-07 21:13:22:Position hold mode started ... #this is probably OK I think this occurs at completion of site survey - my guess.

Also thanks for pointing out where I can measure the EFC voltage.  I'll have to monitor it.

PA0PBZ,
I'm also starting to believe that this L20 may be more of a transformer than just a simple coil/inductor.  I tried to fix and remount the original L20 but I could not solder the loose wires that go on the pads nearest the PCB edge.  I ended up soldering the half that was still attached to L20 pads that go close to the OCS and for the pads near the PCB edge I soldered a small loop of wire.  I really did not have much to work with.  Anyway it still got the same failure. 

So before trying to figure out a new L20 solution I will look at the EFC voltage - perhaps that will provide further insight.

-rastro

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: rastro on June 07, 2016, 11:14:01 pm
hi to all,
received my Symmetricom board yesterday. As to be exspected some damage could be seen. On the top side xtal y1 is missing, inductor L20 was ripped off. On the botton side capacitor C26 and resistor R83 were missing.
R83 could be easily identified as 103 (10kOhm), C26 is in neighbourhood of C27 which I measured as 1.2 uF. I put in 0.56 uF as a provisory measure.
Inductor L20 I measured as 5uH and replaced with a new one. Since xtal Y1 is missing, I suggested it to be 22.118.400 Hz. Is there any kind soul able to confirm this value?
Unit seems to be working fine when injecting 22118400 Hz from an external generator.
regards Goetz
Hello Goetz;
I tried doing something similar to repair my boards damaged L20 but still have problems - perhaps I have additional issues.  I want to verify your solution worked 100% for you.
You replaced L20 with an inductor ~ 5uH. 
1. What type did you use (coil/SMD?)??
2. This was mounted near R105(unpopulated) between the 2 pads nearest the OSC.
3. Did you leave the 2 pads nearest the PCB empty?  L20 has 4 pads.
4. Could you confirm that the board completes the site survey and gets phase lock.  So that LED:GPSLock? = 1 .

Thanks
-rastro
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 08, 2016, 01:01:45 am
Quote
4. status shows #H/W FAIL ---------- [ LINK ] and #OPERATION ALARM --- [ EFC ],  Not sure what LINK i

I believe the H/WFAIL --- is normal, just means it is not sensing another unit. Think they were designed by the mfg to work with another, possible redundancy backup in the field I assume.

Your TFOM is way out, I note just under this statement it shows UCCM-P Status[OXCO warm], mine shows UCCM-P Status[ACTIVE] or UCCM-P Status[HOLDOVER] if it loses sight of enough birds or a antenna disconnect. Are you sure the unit is fully warmed up?

What kind of values should I expect for a valid TFQM?
I think the OSC is warmed up - it's very hot to the touch. 
- If I measure its temperature what should I expect? 
- Is there status command I can use to see the OSC status?
- Also the 12V supply starts at about 500mA when cold then kicks down to lower current after several minutes.  It would appear the oven is regulating.  However I don't know what or how the systems controller makes a determination on when the oven temp is regulated at an working level.

I may try and kluge back on the L20 as some have suggested - I don't think it's gonna be easy because it has very fine wires. 
Has anyone successfully replaced L20 and have a working system i.e. PPL working?

-rastro

As ekyle mentioned it may not be that the OCXO needs warming up but that the EFC voltage is out of range . You want FFOM at 0 and the lowest possible number for TFOM. Personally I have never seen below 2 due to I think limited visibility of satellites. Would be interested if others have seen a TOFM <2.

TFOM (Time Figure of Merit) is the accuracy of the 1 PPS signal, with 0 < 1ns, 1= 1 to 10 ns, 2 = 10 to 100 ns, 3 = 100ns to 1us, ... 9 > 1ms
FFOM (Frequency Figure of Merit) is the stability of the 10MHz signal. 0 = PLL stable, 1 = stabilizing, 2 = holdover, 3 = unlocked (do not use as 10MHz out of spec)

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: kutte on June 08, 2016, 10:40:36 am
Hello Goetz;
I tried doing something similar to repair my boards damaged L20 but still have problems - perhaps I have additional issues.  I want to verify your solution worked 100% for you.
You replaced L20 with an inductor ~ 5uH. 
1. What type did you use (coil/SMD?)??
2. This was mounted near R105(unpopulated) between the 2 pads nearest the OSC.
3. Did you leave the 2 pads nearest the PCB empty?  L20 has 4 pads.
4. Could you confirm that the board completes the site survey and gets phase lock.  So that LED:GPSLock? = 1 .

Thanks
-rastro

hi rastro,
1 . for L20 I used an smd choke 4x4.5 mm 2.2 uH 2.5 A
2 & 3 both yes, I looked at my ripped off L20 and did find only one coil.  L20 is mounted in parallel next to the unpopulated R105
4 yes, my board does run fine (with two green blinking LEDs) and all status messages ok as you can see from my other postings in this thread.
hope this helps Kutte
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: BFX on June 08, 2016, 05:58:55 pm
New member  8) Waiting for antenna and additional cables:)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 08, 2016, 08:32:55 pm
New member  8) Waiting for antenna and additional cables:)
Welcome.  Your board looks in good condition.  I can see one small SMD cap floating in the bag!  Don't lose it!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: BFX on June 08, 2016, 09:36:06 pm
New member  8) Waiting for antenna and additional cables:)
Welcome.  Your board looks in good condition.  I can see one small SMD cap floating in the bag!  Don't lose it!
Thx 8) I will make better photos. I know it is C27. I think it's passed out during transportation, also one corner of PCB is a little damaged.
I should check whole pcb for cold joints or any damages by microscope.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 12, 2016, 06:24:28 pm
I got my simple 1 in 4 out 10MHz distribution working. The RF transformers are probably overkill but I found them at eBay auction: #251401324712 and could not resist.
Schematic attached and bare PCB at cost if anyone else is interested.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 12, 2016, 08:53:34 pm
I see the seller of the Symmetricom boards has just recently swapped out the pictures to the Trimble 57963. Ran out and selling the Trimble?

http://www.ebay.com/itm/331805445560?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/331805445560?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: grumpydoc on June 12, 2016, 09:29:49 pm
I see the seller of the Symmetricom boards has just recently swapped out the pictures to the Trimble 57963. Ran out and selling the Trimble?

http://www.ebay.com/itm/331805445560?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/331805445560?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
Probably - I bought a couple but won't have time to play with them for a while
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: gm8bjf on June 12, 2016, 10:16:08 pm
I just bought one of the Trimbles advertised as Symmetricom units from waikeionline_uk and on testing it will not lock up. The only visible damage was a missing 0 Ohm link which I replaced and that did not cure the problem. The SYST:STAT? page shows the OCXO as warming up after many hours of operation and the LEDs never settle into the fast green flashing mode. Bit stumped with this one. I have asked for a refund or a replacement.

Brian.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 13, 2016, 01:12:55 am
So he is now shipping the Trimble unites?. I THINK that the Trimble 57963 has slightly better specs than the Symmetricom, at least that is my recollection.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: rastro on June 13, 2016, 01:15:38 pm
hi rastro,
1 . for L20 I used an smd choke 4x4.5 mm 2.2 uH 2.5 A
2 & 3 both yes, I looked at my ripped off L20 and did find only one coil.  L20 is mounted in parallel next to the unpopulated R105
4 yes, my board does run fine (with two green blinking LEDs) and all status messages ok as you can see from my other postings in this thread.
hope this helps Kutte
Kutte, thanks for confirmation that the L20 replacement works. 
Since I've done pretty much the same fix on my unit, the problem I am facing is probably due to different issue.

I went back to monitored  the EFC pin on the OSC as ekyle suggested.  This turned out to be a good idea.
1. The unit initially draws 500mA from the 12VDC supply but drops to around 200-250mA in a few minutes.  Temperature of the OSC is hot to the touch.
-- This would be consistent with proper temperature regulation.
2. The 5VDC draws around 200mA .
3. The OCS EFC-Pin reads +13mVDC during OSC warm up and drops to +5mVDC as soon as current drops on the 12VDC (reaching regulated temperature) then stays at that level.
4. Right after 9% of the survey it gets an EFC error on the system status.
Code: [Select]
UCCM-P > status

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [Alarm]
1-2. #Before ACTIVE STATUS ------------- [Wait for GPS]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [GPS]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Ref Analyzing]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [GPS > LINK]
     #ALARM STATUS
     #H/W FAIL ---------- [ EFC ]
     #Bad Quality ------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
At this point it seems that the 10MHz OSC can't adjust frequency to sync up with the GPS values.  I'm guessing that EFC means Electronic Frequency Compensation. 
So now I need to figure out if it is the control circuit or the OSC unit that is the problem. 
Unless I can figure something else out I'll probably desolder the OSC and try and test it with a variable voltage applied to the EFC-pin and see if it loads down or shifts the 10MHz output.

Any other suggestions?

-rastor
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on June 13, 2016, 03:36:29 pm
hi rastro,
1 . for L20 I used an smd choke 4x4.5 mm 2.2 uH 2.5 A
2 & 3 both yes, I looked at my ripped off L20 and did find only one coil.  L20 is mounted in parallel next to the unpopulated R105
4 yes, my board does run fine (with two green blinking LEDs) and all status messages ok as you can see from my other postings in this thread.
hope this helps Kutte
Kutte, thanks for confirmation that the L20 replacement works. 
Since I've done pretty much the same fix on my unit, the problem I am facing is probably due to different issue.

I went back to monitored  the EFC pin on the OSC as ekyle suggested.  This turned out to be a good idea.
1. The unit initially draws 500mA from the 12VDC supply but drops to around 200-250mA in a few minutes.  Temperature of the OSC is hot to the touch.
-- This would be consistent with proper temperature regulation.
2. The 5VDC draws around 200mA .
3. The OCS EFC-Pin reads +13mVDC during OSC warm up and drops to +5mVDC as soon as current drops on the 12VDC (reaching regulated temperature) then stays at that level.
4. Right after 9% of the survey it gets an EFC error on the system status.
Code: [Select]
UCCM-P > status

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [Alarm]
1-2. #Before ACTIVE STATUS ------------- [Wait for GPS]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [GPS]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Ref Analyzing]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [GPS > LINK]
     #ALARM STATUS
     #H/W FAIL ---------- [ EFC ]
     #Bad Quality ------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
At this point it seems that the 10MHz OSC can't adjust frequency to sync up with the GPS values.  I'm guessing that EFC means Electronic Frequency Compensation. 
So now I need to figure out if it is the control circuit or the OSC unit that is the problem. 
Unless I can figure something else out I'll probably desolder the OSC and try and test it with a variable voltage applied to the EFC-pin and see if it loads down or shifts the 10MHz output.

Any other suggestions?

-rastor

The efc-pin should vary the frequency by about 7-8Hz. I pulled mine out and bench tested it. Mine was running cool and I couldn't pull the frequency up. It sounds like yours is running hot and can't pull the frequency down.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: deepskyridge on June 13, 2016, 04:49:00 pm
I just bought one of the Trimbles advertised as Symmetricom units from waikeionline_uk and on testing it will not lock up. The only visible damage was a missing 0 Ohm link which I replaced and that did not cure the problem. The SYST:STAT? page shows the OCXO as warming up after many hours of operation and the LEDs never settle into the fast green flashing mode. Bit stumped with this one. I have asked for a refund or a replacement.

Brian.

I got one of these as well, I found some info over at xdevs:

https://xdevs.com/fix/rb_lpfrs/ (https://xdevs.com/fix/rb_lpfrs/)

The Trimble info is halfway down the page.+

Here's another discussion on time-nuts:

http://time-nuts.febo.narkive.com/O8izIFSh/trimble-gps-board (http://time-nuts.febo.narkive.com/O8izIFSh/trimble-gps-board)

Gary
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on June 13, 2016, 06:46:56 pm
Hook a frequency counter or scope to the rf output of the ocxo. If it is not around 10 Mhz there is a issue. If it is a lot out post the frequency, im curious >:D .
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: deepskyridge on June 14, 2016, 06:24:23 pm
Does anyone have a pinout for the 50 pin FPC connector on these units ?

Thanks

Gary
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: dpersuhn on June 14, 2016, 11:27:04 pm
Just picked up a preassembled GPSDO based on the symmetricom board and I thought all was going reasonably well.  I fired it up, it surveyed for a few hours, locked, and life was good.  Then I came home from work today and saw a new bit of LED blink action going on.  Lock is solid, but "on" is blinking.  Here's what I now have:

UCCM-P > system:status?
-------------------------------------------------------------------------------
090-03861-03   serial number W561002396   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     4             FFOM     2
                                              UCCM-P Status[HOLDOVER]

   GPS: [no ref]
ACQUISITION .............................................. [ GPS 1PPS Invalid ]
Tracking: 0 ____   Not Tracking: 0 ________   Time ____________________________
                                              GPS      15:27:57     14 JUN 2016
                                              GPS      Invalid: GPS rcvr failed
                                              ANT DLY  +0.000E+00
                                              Position ________________________
                                              MODE     Hold

                                              LAT      N  XX:37:29.862
                                              LON      W  XX:57:09.846
                                              HGT              +351.30 m  (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------

Command Complete



UCCM-P > posstatus
-----------------------------------------------------------------------------
6/14/2016 15:28:19
-----------------------------------------------------------------------------
 Position : LAT(N XX:37:29.862) LON(W XX:57:9.846) H(351.30 m MSL)
-----------------------------------------------------------------------------
 Geometry : PDOP(0.0) HDOP(0.0) VDOP(0.0)
-----------------------------------------------------------------------------
 Channel Status
   num of visible sats > 10
   num of sats tracked > 6
   ------ Receiver Channel State ------
     CH 0 >  SateID(10) TrackMode(code search) SigValue(39)
     CH 1 >  SateID(14) TrackMode(code search) SigValue(34)
     CH 2 >  SateID(22) TrackMode(code search) SigValue(35)
     CH 3 >  SateID(26) TrackMode(code search) SigValue(35)
     CH 4 >  SateID(31) TrackMode(code search) SigValue(42)
     CH 5 >  SateID(32) TrackMode(code search) SigValue(31)
     CH 6 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 7 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 8 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 9 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 10 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 11 >  SateID(0) TrackMode(code search) SigValue(0)
-----------------------------------------------------------------------------
  Rcvr Status(2) :
-----------------------------------------------------------------------------
  Antenna Voltage: 5735 mV,  Antenna Current: 23 mA
-----------------------------------------------------------------------------
Command Complete



UCCM-P > gps:sat:trac?
"Data corrupt or stale"
UCCM-P >


WTF?  Worked for about 16 hours then went in the tank.  Has anyone else seen this before?  Its bee in holdover mode for the last 9 hours, but says it is tracking 6 satellites, yet all 6 show code search instead of pos available.  Reboot and all is back to swell and it happily starts surveying again.


Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on June 15, 2016, 12:33:01 am
Hi

Watch the survey location. Get a location from another GPS (even a USB stick) and see how it's doing. If (for some reason) the survey heads for the next county, you will pretty much never get back to your location.

No idea *why* this would happen, it's just one on the list of "how come?" issues that you can check out.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 15, 2016, 12:42:41 am
I have Lady Heather working with the Z3801A (and probably all the Z38xx and HP5xxxx device, but I don't have any to test).  SCPI devices were NOT designed with computer control in mind and it was a real mother to get it working properly.   It doesn't take much deviation in the expected responses for it to all fall apart.   I have a couple of these devices (Symmetricom and Trimble) on order and hope to get the good Lady Heather working with them.

Lady Heather now also speaks NMEA,  Ublox,  Zodiac (Jupiter-T), Motorola 6/8/12 channel), SCPI, TSIP, and GPSD (with Venus and Sirf on the calendar)... and can do it under Windoze or Linux.  Remote accesses to a receiver can be via either IPv4 or IPv6.  Receiver type auto-detection is possible if it is running at 9600:8N1 (or is a Z3801A at 19200:7O1)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: dpersuhn on June 15, 2016, 12:54:28 am
Its weird.  The original survey pretty much put it on my lap according to a google earth mapping of the LAT/LON coordinates.  This time it is taking forever to settle on satellites that it likes.  10 visible, its been screwing around for an hour and hasn't managed to go above 4 that happen to have too poor of a geometry for it to continue surveying at the moment.  Sucks to only have clear sky to the west, but that still doesn't answer why it would just decide to go retarded after 16 hours.  I'd consider a better antenna if I had a measure of confidence that signal strength had anything to do with it.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on June 15, 2016, 01:09:04 am
Its weird.  The original survey pretty much put it on my lap according to a google earth mapping of the LAT/LON coordinates.  This time it is taking forever to settle on satellites that it likes.  10 visible, its been screwing around for an hour and hasn't managed to go above 4 that happen to have too poor of a geometry for it to continue surveying at the moment.  Sucks to only have clear sky to the west, but that still doesn't answer why it would just decide to go retarded after 16 hours.  I'd consider a better antenna if I had a measure of confidence that signal strength had anything to do with it.

Hi

Ahhh, that question I can answer.

If you have a poor antenna location and a view mainly in one direction, you can get in trouble. The constellation of sats moves around. You can watch the "best guess" location move as they do this. If you have a multi path issue on top of a one direction view, the location can take a *major* jump. If the unit is still set for "timing compatible" limits on elevation mask, it may never really get a good set of sats for location. Timing wants a bunch of sats straight overhead. Location wants them as spread out as they possibly can get.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: dpersuhn on June 15, 2016, 01:29:12 am
I take it that is the EMANgle setting, which mine reports back as +5.  Forgive my ignorance about the difference between timing and location optimization for GPS.  I can see why having a bunch of overhead satellites would be preferred for timing, as they would incul much less signal delay and atmospheric interference.  I also acknowledge why that would be less than ideal for location.  The two questions it leaves me with are 1.Should I modify the emangle satting?  What affect would that have on timing accuracy (what I really care about)?

Correction on the horizon facing direction, its more southwest than west.

After two hours, I now have 8 satellites locked and surveying is happy again.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 15, 2016, 01:47:34 am

T1#H4430443220000B0
T1#H4430443420000B2
T1#H4430443620000B4

I cannot get the checksum calculation to work with these.  I thought it was meant to be the last 2 characters were the HEX of a sum of the ASCII values of the preceeding characters... weird I get 7A, 7C, 7E not B0, B2 and B4.


That number is the hex representation of the number of seconds since 6 Jan 1980.   Since yours is incrementing by 2, you are probably running in pulse-per-2-seconds mode.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 15, 2016, 07:18:50 am
That number is the hex representation of the number of seconds since 6 Jan 1980.   Since yours is incrementing by 2, you are probably running in pulse-per-2-seconds mode.

T1#H4430443220000B0

At this time there are roughly 448B5D00 seconds since 6 Jan 1980 so that explains the first 8 characters after the literal T1#H

But what about the 20000B0?

I don't use this input anyway now, it is in GPS time, I use the GPS Receiver UTC time output.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 15, 2016, 02:13:37 pm
But what about the 20000B0?

Last 7 chars are t f l r v cc:
   t=TFOM time figure of merit
   f=FFOM frequency figure of merit
   l=LEAPSECOND pending ('0'=none, '+'=forward, '-'=backwards)
   r=REQUEST for service summary bit of the status byte register
   v=VALIDITY of time related info (0=valid, 1=invalid)
   cc=checksum of all preceding ASCII chars

This comes from the Z3801A manual...

There is also a T2 format where the date/time is in ASCII.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 15, 2016, 03:13:35 pm
   cc=checksum of all preceding ASCII chars
The reason for my original post is I couldn't get the checksum to work.  Have you tried?
(I can't really remember now but I think the samples I gave were just random examples, they weren't meant to be particularly sequential or complete)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 15, 2016, 03:37:00 pm

The reason for my original post is I couldn't get the checksum to work.  Have you tried?
(I can't really remember now but I think the samples I gave were just random examples, they weren't meant to be particularly sequential or complete)

No, my code just ignores the checksum...  I run the Z38xx's in time format T2 mode, but can handle T1 messages.  I do seem to vaguely remember something like a leading ' ' being included or excluded.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 16, 2016, 07:26:37 am
I run the Z38xx's in time format T2 mode
I tried but failed to change the time format on the UCCM-P.  I think it only supports T1 (and since that is in GPS time not UTC isn't very useful to me).
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 16, 2016, 01:44:43 pm
I tried but failed to change the time format on the UCCM-P.  I think it only supports T1 (and since that is in GPS time not UTC isn't very useful to me).

If you can get the leapsecond offset count, you can add it to GPS time to get UTC.  I do that to convert UTC time to GPS time on receivers that do not support GPS time.   It is particularly easy to do if you can convert Julian date/time to Gregorian.  Get the seconds from the T1 message, add the leapsecond offset,  add Julian seconds of 6 Jan 1980,  convert to Gregorian.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 16, 2016, 02:15:54 pm
Try sending:

:PTIM:LEAP:ACC?   (maybe without the leading ':') and see if you get the leapsecond offset back...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 16, 2016, 02:34:46 pm
UTC time is available from the GPS module, that's where I get it from with one wire.  No need to mess with GPS leap seconds.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 16, 2016, 03:44:14 pm
If you (or somebofy else) can,  please try the :PTIM:LEAP:ACC? command with and without the leading ':' and let me know the responses.  It will answer most of the questions that I have about what I need to mod in Lady Heather to be able to control these units.  Heather is currently working with SCPI receivers like the Z3801A.  If I can use (most of) my existing SCPI code instead of having to do special UCCM commands it will make life a lot easier... the SCPI commands are a lot more capable than the UCCM commands.  It will be a few weeks before my UCCM devices come it.

Another command to try is (with / without leading ':'
   :DIAG:GPS:UTC 0
   :DIAG:GPS:UTC 1

This might switch the receiver between GPS and UTC mode.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 16, 2016, 03:48:56 pm
the SCPI commands are a lot more capable than the UCCM commands.
UCCM-P commands are SCPI commands.  You will find, when you receive your device, that UCCM-P are a poor subset of what you are used to.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 16, 2016, 04:15:23 pm
UCCM commands are in the SCPI format, but they are not the same as the standard SCPI GPSDO commands.  It appears that these UCCM devices do respond to many of the standard SCPI GPSDO commands... I'm trying to find out just how well they do that (without waiting weeks for mine to come in), hence my request.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 17, 2016, 12:24:26 am
If you (or somebofy else) can,  please try the :PTIM:LEAP:ACC? command with and without the leading ':' and let me know the responses.  It will answer most of the questions that I have about what I need to mod in Lady Heather to be able to control these units.  Heather is currently working with SCPI receivers like the Z3801A.  If I can use (most of) my existing SCPI code instead of having to do special UCCM commands it will make life a lot easier... the SCPI commands are a lot more capable than the UCCM commands.  It will be a few weeks before my UCCM devices come it.

Another command to try is (with / without leading ':'
   :DIAG:GPS:UTC 0
   :DIAG:GPS:UTC 1

This might switch the receiver between GPS and UTC mode.

"Undefined Header" is the response for :PTIM:LEAP:ACC? with and without the header, same with the DIAG commands, I tried DIAGNOSTIC, no luck. Here is the list of "supported commands", although I have found with others that there is some undocumented commands that will work. Perhaps it's getting the syntax right.

Code: [Select]
?
*IDN?
ALARm:HARDware?
ALARm:OPERation?
DIAGnostic:OUTPut ON|OFF
OUTPut:ACTive:ENABle
OUTPut:ACTive:DISable
OUTPut:ACTive:HOLDover:DURation:THReshold <seconds>
OUTPut:ACTive:HOLDover:DURation:THReshold?
OUTPut:INACTive
OUTPut:INACTive?
OUTPut:STATe?
SYNChronization:HOLDover:DURation:STATus:THReshold <seconds>
SYSTem:PRESet
SYNChronization:TFOMerit?
LED:GPSLock?
SYNChronization:FFOMerit?
GPS:POSition N or S,<deg>,<min>,<sec>,E or W,<deg>,<min>,<sec>,<height>
GPS:POSition?
GPS:POSition:HOLD:LAST?
GPS:REFerence:ADELay <numeric value>
GPS:REFerence:ADELay?
GPS:SATellite:TRACking:COUNt?
GPS:SATellite:TRACking?
DIAGnostic:ROSCillator:EFControl:RELative?
SYNChronization:TINTerval?
DIAGnostic:LOG:READ:ALL?
DIAGnostic:LOG:CLEar
SYSTem:PON
OUTPut:MODE?
SYSTem:STATus?
SYSTem:COMMunication:SERial1:BAUD 9600|19200|38400|57600
SYSTem:COMMunication:SERial1:BAUD?
SYSTem:COMMunication:SERial1:PRESet
SYSTem:COMMunication:SERial2:BAUD 9600|19200|38400|57600
SYSTem:COMMunication:SERial2:BAUD?
SYSTem:COMMunication:SERial2:PRESet
OUTPut:STANby:THReshold <seconds>
changeSN
SYNChronization:REFerence:ENABLE LINK|GPS
SYNChronization:REFerence:DISABLE LINK|GPS
SYNChronization:REFerence:ENABLE?
STATus
POSSTATus
TOD EN|DI
TIME:STRing?
REFerence:TYPE GPS|LINK
REFerence:TYPE?
PULLINRANGE 0|1|2|...|254|255
PULLINRNAGE?
DIAGnostic:LOOP?
DIAGnostic:ROSCillator:EFControl:DATA GPS|<value>
DIAGnostic:ROSCillator:EFControl:DATA?
OUTPut:TP:SELection PP1S|PP2S
OUTPut:TP:SELection?
GPSystem:SATellite:TRACking:EMANgle <degrees>
GPSystem:SATellite:TRACking:EMANgle?
DIAGnostic:TCODe:STATus:AMASk
DIAGnostic:TCODe:STATus:OMASk
DIAGnostic:TCODe:ERRor:AMASk
DIAGnostic:TCODe:ERRor:OMASk
DIAGnostic:HOLDover:DELay
DIAGnostic:HOLDover:DELay?
GPS:SATellite:TRACking:IGNore <PRN>, ...,<PRN>
GPS:SATellite:TRACking:IGNore?
GPS:SATellite:TRACking:INCLude <PRN>, ...,<PRN>
GPS:SATellite:TRACking:INCLude?
GPS:SATellite:TRACking:<select>:ALL
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 17, 2016, 02:48:56 am
Thanks for trying those...  I've got the list of "official" commands... it's the undocumented ones that are where the action is.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 17, 2016, 05:57:26 am
PTIM:LEAP? returns 0 if that helps.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 17, 2016, 07:11:52 am
PTIM:LEAP? returns 0 if that helps.

Hmmm... that's a new one.  I suspect 0 means no leapsecond pending.  (-1) says backwards leap pending (will probably never happen unless the world gets hit by an asteroid), 1 says forward leap pending.

How about (from the HP53xxx manual):
  PTIM:LEAP:DATE?
  PTIM:LEAP:DUR?
  PTIM:LEAP:STAT?

Also on "PTIM:LEAP?" does it matter if you do ":PTIM:LEAP?"
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 18, 2016, 06:13:42 am
Quote

Hmmm... that's a new one.  I suspect 0 means no leapsecond pending.  (-1) says backwards leap pending (will probably never happen unless the world gets hit by an asteroid), 1 says forward leap pending.

How about (from the HP53xxx manual):
  PTIM:LEAP:DATE?
  PTIM:LEAP:DUR?
  PTIM:LEAP:STAT?

Also on "PTIM:LEAP?" does it matter if you do ":PTIM:LEAP?"



 PTIM:LEAP:DATE?
"Undefined Header"
PTIM:LEAP:DUR?
"Undefined Header"
 PTIM:LEAP:STAT?
"Undefined Header"

Nope, none worked, even tried removing the leading colon:, as well as various combinations of removing LEAP and PTIM

Quote
Also on "PTIM:LEAP?" does it matter if you do ":PTIM:LEAP?"

Works with a leading colon : , returns "0"
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 18, 2016, 06:23:11 am
Ugh... I detect suckage in the force...

Many thanks for trying those.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 18, 2016, 07:42:17 am
Yes, too bad. Hope you still are able to get these receivers to communicate with Lady Heather, would be most appreciated. I just downloaded the latest version (Beta) and could not get it to communicate with the Com port. Changed the baud rate to 57600 in Windows, but still no luck.

Anything else you need tested let me know, don't mind testing commands.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 18, 2016, 08:39:43 am
The Lady Heather beta on the ke5fx.com site is ver 4.00,  my development version is up to 4.08 ... it changes hourly.   I don't think 4.00 had support for anything but TSIP receivers,  but it could compile for Linux.    Once the development version stabilizes, I'll shoot John a new copy.

Something tells me the UCCM devices are going to be a pain in the latus rectum to do... 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 18, 2016, 08:57:29 am
Aah, knew it was redone for Linux, but thought there was some other improvements as well. Yes, think it will be a uphill battle with the UCCM unless somewhere out there a complete list of undocumented commands for the device is found. Think you will may need the NMEA data from the GPS receiver to get what you need.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 18, 2016, 07:02:54 pm
Well,  I'll just try all the SCPI commands that Lady Heather sends and see which ones work,  which ones need changing,  and which ones have no work-around.

UCCM has some annoying protocol differences (like that "Command complete" thing,  differences in the SYST:STATUS response,  differences in the error responses, etc.

Lady Heather does support NMEA,  but I don't do any of the manufacturer proprietary commands.  There is a way to send those manually... but I don't parse any of the proprietary responses.  Besides, tying into the receiver TX data is not something most people will do.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on June 18, 2016, 07:17:52 pm
Well,  I'll just try all the SCPI commands that Lady Heather sends and see which ones work,  which ones need changing,  and which ones have no work-around.

UCCM has some annoying protocol differences (like that "Command complete" thing,  differences in the SYST:STATUS response,  differences in the error responses, etc.

Lady Heather does support NMEA,  but I don't do any of the manufacturer proprietary commands.  There is a way to send those manually... but I don't parse any of the proprietary responses.  Besides, tying into the receiver TX data is not something most people will do.

Hi

With some luck you might find one that puts the module directly into Mayan Calendar mode ....

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 18, 2016, 08:13:56 pm
There is a way to send those manually... but I don't parse any of the proprietary responses.  Besides, tying into the receiver TX data is not something most people will do.

Probably not, as if it is integrated into a serial device their would be the necessity of a RS232/TTL converter. To add to the complexity the NMEA commands are not returned with a checksum either.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 18, 2016, 08:43:29 pm
Lady Heather don't need no stinkin' checksums.  Checksums are optional in NMEAville and a NMEA parser that can't work without them is defective... as is a NMEA receiver that requires them.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on June 21, 2016, 06:50:48 pm
I just felt lucky yesterday and managed to fix 3 out of the 6 in the sh*t pile, and found the probable cause of the alarm 0200 (0.5 Hz) error.
When L20 gets ripped off including the upper 2 pads (a common failure I think, I have 3 boards like that) it breaks the traces to the unpopulated R105 position. But... there is also a trace going from the upper left pad to R97 and that gets also destroyed in the action. So when you just put a new coil on the R105 pads you will miss the connection to R97, which I'm my case caused the alarm 0200.

Like they say, a picture is worth a thousand words: (this is one of the 2 boards nominated as parts donor)

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=235160;image)

I think I'm done fixing now, I'm out of several components (Like Y1) and I have 4 working ones so I'm good for a while. If anyone is looking for the odd component and I still have spares I can send it to you, just let me know where you are looking for.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on June 21, 2016, 09:32:02 pm
... found the probable cause of the alarm 0200 (0.5 Hz) error.
Oh wow!  I had "Alarms:  [0200] 0.5Hz Internal Reference" on the board I sent back (and never got refunded for from that crook flyxy2015).

PA0PBZ That's a brilliant bit of work. Respect!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 22, 2016, 01:02:01 am
When L20 gets ripped off including the upper 2 pads (a common failure I think, I have 3 boards like that) it breaks the traces to the unpopulated R105 position. But... there is also a trace going from the upper left pad to R97 and that gets also destroyed in the action. So when you just put a new coil on the R105 pads you will miss the connection to R97, which I'm my case caused the alarm 0200.

Great catch, sure to help out others.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on June 22, 2016, 03:37:40 pm
I tried but failed to change the time format on the UCCM-P.  I think it only supports T1 (and since that is in GPS time not UTC isn't very useful to me).

If you can get the leapsecond offset count, you can add it to GPS time to get UTC.  I do that to convert UTC time to GPS time on receivers that do not support GPS time.   It is particularly easy to do if you can convert Julian date/time to Gregorian.  Get the seconds from the T1 message, add the leapsecond offset,  add Julian seconds of 6 Jan 1980,  convert to Gregorian.

The only way I have figured to get UTC time is with the TOD EN command and decoding the ascii-hex output that repeats until a TOD DI command is sent. I have my serial interrupt handle these packets and filter them out, easy enough because each packet starts with 'c5' byte and ends with 'ca' followed by space, cr, lf. Regular expression "c5.{127}ca\s\r\n" gets it for me.

I've no idea what most of those bytes are, but seconds since 6 Jan 1980 are bytes 28-31. I believe the offset is byte 33 but I can't be sure until they change the leap second again ;)

Observing the logs I do see byte 33 switch from 00 to 11 (17 seconds) exactly when the SYST:STAT? reports 'Synchronized to UTC' instead of 'Synchronized to GPS'

Code: [Select]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 3 ____   Not Tracking: 4 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      13:20:41     22 JUN 2016
 21  33 164   34     5   9  69                GPS      Synchronized to GPS
 25  32 108   37     9   5 345                ANT DLY  +0.000E+00
 29  59  66   41    16  16 287                Position ________________________
                    31  59 221                MODE     Hold

...                                                                              ** ** ** **    **
c5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 44 95 53 2a 00 00 60 04 85 40 00 00 00 00 ce 94 ca
c5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 44 95 53 2c 00 00 60 04 85 40 00 00 00 00 f5 f3 ca
c5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 44 95 53 2e 00 00 60 04 85 40 00 00 00 00 33 31 ca
...

ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 3 ____   Not Tracking: 4 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      13:22:09     22 JUN 2016
 21  33 163   30     5  10  68                GPS      Synchronized to UTC
 25  31 109   38     9   5 345                ANT DLY  +0.000E+00
 29  58  65   43    16  16 287                Position ________________________
                    31  58 220                MODE     Hold

...                                                                              ** ** ** **    **
c5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 44 95 53 82 00 11 60 04 85 40 00 00 00 00 db 6b ca
c5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 44 95 53 84 00 11 60 04 85 40 00 00 00 00 d0 0c ca
c5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 44 95 53 86 00 11 60 04 85 40 00 00 00 00 26 ce ca

The TOD message can interrupt regular terminal output like in the middle of a SYST:STAT? response for example, but nothing appears to mangle the TOD stream. The TOD output occurs every 2 seconds whether in 1PPS or PP2S modes. I have also checked the timing between the actual 1PPS output and the data burst on my scope. I've found the end of the TOD packet (at 57600 baud) occurs between 90ms - 100ms of the actual pulse.

Another byte I have observed is 37. It indicates 40 if GPS PPS valid, 50 if invalid, and 60 when the GPS antenna is unplugged.

Of course the TOD output keeps time and continues in these conditions, unlike NMEA.

So I think I will build a Raspberry Pi NTP server using the TOD output  :-+
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 23, 2016, 04:32:34 am
One of my units (a Trimble) came in today.  It was in excellent condition,  no broken stuff, no goo.   I have Lady Heather sort of talking to it.

I thought that the fact that the units echo the incoming commands was going to cause lots of problems,  but it actually solves a MAJOR issue with SCPI receivers... telling what message that a response is associated with.   It makes the code quite a bit simpler and more robust.

The Trimble receivers do NOT send the TOD string in the middle of another messages' response.  That is a very good thing.  The Symmetricom units are going to need some major kludgeoscity to handle that little issue.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TiN on June 23, 2016, 04:38:24 am
Just 5c, "Undefined Header" for PTIM:LEAP? on my OEM Trimble too.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on June 23, 2016, 02:18:09 pm
The Trimble receivers do NOT send the TOD string in the middle of another messages' response.  That is a very good thing.  The Symmetricom units are going to need some major kludgeoscity to handle that little issue.
I guess you could implement polling. When you need it send a TOD EN, wait for the packet with just over a 2 second timeout, then immediately send a TOD DI. Process ordinary SCPI commands as usual

I implemented a low level kludge using the serial data arrival interrupt because I've been coding an interactive terminal in C# .NET and so stripping these packets out and processing them "behind the scenes". If the GPS module is entirely under program control then polling would be simpler.

Another minor thing, I believe the Trimble sends its ascii-hex in uppercase and the Symmetricom lower. Symmetricom has an ending space character at the end of the line before the CR LF, not sure if that's the case with Trimble or the order of LF CR.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: deepskyridge on June 23, 2016, 03:40:29 pm
Yesterday I received the GPSDO I bought from waikeionline_uk. Attached is a picture of the board.

The 2 sma connectors are missing and the mounting pads for them are also missing, the coax from the GPS can has been cut.

Also his ad shows a Trimble board.

I have requested replacement or refund, have any of you dealt with this seller before ?

Gary

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 23, 2016, 03:51:56 pm
Looks like he has closed the listing and probably only had a few junk units to get rid off, wouldn't count on getting a replacement.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 23, 2016, 04:55:29 pm
Another minor thing, I believe the Trimble sends its ascii-hex in uppercase and the Symmetricom lower. Symmetricom has an ending space character at the end of the line before the CR LF, not sure if that's the case with Trimble or the order of LF CR.

The Trimble sends a NULL character with every line of the SYST:STATUS? display.

I am using the TOD string to drive the display and polling for additional messages... without it, Lady Heather won't work...

Attached is an overnight run of the first hack of the code... It's plotting the DAC voltage, TINT value, and sat count.  Lady Heather normally expects consecutive time stamps and flags missing and duplicated ones with those red ticks at the top of the plot area.  The satellites in the analog watch display should have trails behind them,  but I need to add the code that does that (and a whole lot more).

Now I need to get it all tweaked up for what the units can do...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on June 23, 2016, 06:51:43 pm
I have requested replacement or refund, have any of you dealt with this seller before ?

Read the thread :)
After dealing with him for some time (either _us or _uk) I'm convinced that he just buys and have them shipped by another party. He has no idea what was shipped to you so his first question will be to send him pictures of what you received. Then he promises to send a replacement but only after you send back what you got. Again he has no idea how the replacement will look and mine even came from a different address again. I told him it looks like he gets scr*wed by his business partner:

Quote
I'm not sure who told you that the damage is occurring during transport but this is definitely not true! All boards I received where shipped damaged and there is a very easy way to tell: none of the missing components where in the sealed envelopes, so they where never on the shipped boards.
The damage must have been done while these boards were taken out of the original equipment with tools not good for the job and by people not caring and without knowledge. I have seen examples where the connectors where ripped off the boards because people did not understand how to disconnect them.

I still think that you worked with business partners to ship these boards and they are just not honest to you. Be careful with these people...

His response:

Quote
Thanks for your understanding,
We will make improvement on our service asap,

Many thanks

Looks like he didn't work that out yet  ;)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 23, 2016, 07:02:35 pm
I got mine from him (_uk).  It arrived in about a week (shipped from China) and was in perfect condition.  No broken parts or slime.  Paid about $45.  Well worth it... maybe I just got lucky and should play the lottery this week.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on June 23, 2016, 09:52:30 pm
Don't bother with the lottery.  You've used up all your good luck!  ;)

What kind of AlDev numbers are you getting?

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 23, 2016, 09:58:28 pm
I haven't done any analysis on the adevs, etc.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 24, 2016, 02:07:53 am
I did some more poking and prodding of the Trimble receiver.  If you do a SYST:PRES command it resets to the factory defaults and starts a 30 minute self survey.  There is a command to enter your own coordinates which will stop the self survey.   Once the survey completes or it has user coordinates, it stores the location into EEPROM.  A power-cycle will re-load the saved coordinates from EEPROM and does not cause another survey.

I assume, but have not tested, that if you move the unit significantly it will detect that and automatically start a new survey...  That is pretty much standard for timing receivers.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on June 24, 2016, 03:03:40 pm
I assume, but have not tested, that if you move the unit significantly it will detect that and automatically start a new survey...  That is pretty much standard for timing receivers.

I moved the antenna for my Symmetricom version about 40 feet and tried the original coordinates. It got very confused and would drop and add satellites every other second. Everything worked again when I did a new survey. I think if it's moved at all, a new survey should be done.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on June 24, 2016, 03:16:08 pm
 Hi The Symmetricom Does a new survey any time the power is interrupted
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on June 24, 2016, 03:34:43 pm
I assume, but have not tested, that if you move the unit significantly it will detect that and automatically start a new survey...  That is pretty much standard for timing receivers.

I moved the antenna for my Symmetricom version about 40 feet and tried the original coordinates. It got very confused and would drop and add satellites every other second. Everything worked again when I did a new survey. I think if it's moved at all, a new survey should be done.

Hi

Forty feet may not be far enough for it to really *know* it has moved.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 25, 2016, 09:24:33 am
Hi The Symmetricom Does a new survey any time the power is interrupted
Dave

I second that, Texaspyro are you sure the Trimble saves the survey, doesn't seem to happen with the Symmetricom
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on June 25, 2016, 04:02:40 pm
Yes the Trimble does save it
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on June 26, 2016, 08:14:31 am
Yes the Trimble does save it
Dave

+1
The Trimble does save the survey.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 26, 2016, 05:05:31 pm
Just for grins I tried powering my Trimble unit with a 2A Samsung USB charger wall wart.  It works!  The USB type AS to barrel plug cable wires are rather thin and around 3 feet long.  When cold the voltage at the Trimble was 4.2V,  warmed up it was 4.6V  Unloaded, the charger output was 5.23V
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 26, 2016, 10:02:17 pm
I have Lady Heather working pretty well with my Trimble unit. 

I added some code to poll and read the DIAG:LOOP? message.  The main value that seems interesting is the FREQ DIFF value.  I log and plot that as the "OSC" parameter.   It is 0.0 if the unit is not discipling the oscillator (power-up, user turned off disciplining by setting a fixed DAC value, etc).   

Occasionally the FREQ DIFF has a bogus value -2.79E-07.  I treat this as noise and ignore that reading.   One very interesting thing that I noticed is than once an hour (at xx:26:26) the loop goes a bit whacky.  It looks like the firmware does something that upsets / resets / whatever-sets the PLL.   Attached is a plot of the resulting havoc...  It takes around 3 minutes for the loop to start settling down,  but takes around 18 minutes to stabilize and 36 minutes to really dampen out... only to have it's bell rung 24 minutes after that.



Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on June 27, 2016, 01:25:10 am
Do you have/offering a link to the beta software. Would like to give it a go with the Symmetricom.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on June 27, 2016, 01:31:48 am
Do you have/offering a link to the beta software. Would like to give it a go with the Symmetricom.

Hi

Does the beta code handle the Bolivian calendar properly?

http://www.bbc.com/news/world-latin-america-36595192 (http://www.bbc.com/news/world-latin-america-36595192)

One *must* keep up to date.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 27, 2016, 02:21:34 am
Do you have/offering a link to the beta software. Would like to give it a go with the Symmetricom.

Hi

Does the beta code handle the Bolivian calendar properly?

http://www.bbc.com/news/world-latin-america-36595192 (http://www.bbc.com/news/world-latin-america-36595192)

One *must* keep up to date.

Bob

Why, yes it does!  Lady Heather know all,  speaks all,  clocks all.  Has support for various Mayan, Inca, and Aztec calendars (and being pan-denominational Druid, Jewish, Islamic, Persian, Afghan, Kurdish, Indian, and a whole lot of others).   

The 13 month years are key to the Tzolkin calendars (both Mayan and Aztec have their own versions).  That heretical year 1492 offset can be accommodated by specifying an offset to the real calendar using the "set Mayan correlation offset" command...  the archaeological dweebs can't agree about when the reference date of the calendars should be, so there is a "correlation factor" adjustment capability.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 27, 2016, 02:24:57 am
Do you have/offering a link to the beta software. Would like to give it a go with the Symmetricom.

Not yet,  still waiting on my Symmeticom to come in.  I know that it has some incompatibilities with the Trimble that must be fixed.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on June 27, 2016, 02:34:39 am
I've made a very nice discovery this evening. I know there have been several questions posted about a battery backup for the GPS data. Well, I was looking at the silk screen printing for J3. It reads 1:Rx, 2:Tx,3:BT,4:GD. 1,2 are of course the serial port. 4 is ground. BT.... Could it be short for battery? While the unit was on I measured about 3.2v on pin 3. I hooked up a power supply to pin3 and removed power on the unit. I waited a while and plugged it back in. It booted and I could see immediately that it had the GPS location and was in hold mode. Now for the bad news. With the unit powered off, it draws about 88ma from this pin and 0ma when its on. It could be that it keeps the GPS receiver alive with it. Definitely not just a CMOS memory backup. I'm not sure if its current limited so a super cap could be used on it.

I suspect that BT may be a built-it-test-system status output... almost all the telco reference units and rubidium oscillators have some sort of BITS signal.  Connecting a voltage source to it is probably powering the electronics through the protection diodes in whatever chip it goes to (and stressing the hell out it).  There is no way a memory backup line would draw 88 mA.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on June 28, 2016, 03:01:48 am


I suspect that BT may be a built-it-test-system status output... almost all the telco reference units and rubidium oscillators have some sort of BITS signal.  Connecting a voltage source to it is probably powering the electronics through the protection diodes in whatever chip it goes to (and stressing the hell out it).  There is no way a memory backup line would draw 88 mA.
[/quote]

Good point there! That may very well be the case that it is a logic gate output.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: gm8bjf on June 30, 2016, 01:16:08 pm
Phase noise checks on UCCM-P units.

I now have several Symetricom units and one Trimble UCCM-P unit. I have been making some comparative measurements of their phase noise (PN) performance as I want to use them as references for microwave PLLs. I did these checks using the PLL technique and compared them to a couple of HP10811 OCXOs that I have which are probably as good a PN standard as I can easily (and reasonable cheaply) lay my hands on. I also have some bare OCXOs off the Symetricom and Trimble units. (The ones I could not raise from the dead!)

I found that the PN seems to be determined by the OCXOs in use which is not surprising and suggests the locking/disciplining process is not degrading the PN which is reassuring. The Symetricon units are better than the Trimble units by 10- 12 dB and the Symetricom was only 2-3 dB worse that the than the HP10811.  The Trimble units did seem relatively noisy and it comes from the OCXO.

To detect the PN I was using a HP 11848 PN test set and measuring the demodulated output noise with a HP 3400 rms voltmeter. I have not managed to stumble across the proper FFT analyser for the HP3048 test set yet. A computer sound card and and audio spectrum analyser programme also works if you can do enough averaging on the signal.

I need to compare them to my Z3801 now!

Hope that is of passing interest,

73s
Brian GM8BJF
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 03, 2016, 04:08:52 am
I got in my Symmetricom unit (and another Trimble).  Both (from the same seller) arrived in excellent condition (except the parcel smashers had their way with the well packed box).

I have Lady Heather working fairly well with it.   Along the way I noticed a couple of things...  The time stamp message does not seem to be sent in the middle of things like the SYST:STAT? command results like some people have reported.  It can come out while one is in the middle of sending a command to the unit... when that happens that command is corrupted and you get an "undefined header" response.

Also, it occasionally skips sending the time stamp message.

You can stop the power-on self survey by sending your position to the unit.  No setting that you made to the unit survive a power-cycle.

I think that the altitude that it reports is in MSL, not WGS84 geoid height.  It is about 20 meters too high for WGS84.

Attached is a screen dump from an 8-hour run.  The TEMP plot is a plot of the "temp corr" value multipled by 1E12... it is mislabeled as being in degrees (should probably be labeled as in being in PPT (parts per trillon).  The OSC plot is the "freq corr" value. The PPS plot is from the SYNC:TINT? message.

 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on July 03, 2016, 12:20:51 pm
The time stamp message does not seem to be sent in the middle of things like the SYST:STAT? command results like some people have reported.  It can come out while one is in the middle of sending a command to the unit... when that happens that command is corrupted and you get an "undefined header" response.

Also, it occasionally skips sending the time stamp message.
Odd. I have the exact opposite behaviour. I did think maybe you have a different firmware but your screen shot shows the same as mine, 1.0.0.2-01

Just to test my sanity I fired it up from cold and logged the results using PuTTY

Code: [Select]
=~=~=~=~=~=~=~=~=~=~=~= PuTTY log 2016.07.03 12:52:16 =~=~=~=~=~=~=~=~=~=~=~=
 

Symmetricom Boot Code ver. 1.01.01


Press Enter to go to boot
Image1: [1.0.0.2] [454535 bytes] [valid checksum:0x20AFA24] [timestamp:3]
Image2: [1.0.0.1] [454535 bytes] [valid checksum:0x2142B89] [timestamp:2]

Loading Image1
 UCCM-P > *IDN?
Symmetricom,090-03861-03,W5609120082,1.0.0.2-01
Command Complete
UCCM-P > TOD EN
Command Complete
UCCM-P > c5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 00 00 00 22 00 00 41 00 8f 50 00 00 00 00 97 72 ca
SYSc5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 00 00 00 24 00 00 41 00 8f 50 00 00 00 00 9c 15 ca
T:STATc5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 00 00 00 26 00 00 41 00 8f 50 00 00 00 00 6a d7 ca
?c5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 00 00 00 28 00 00 41 00 8f 50 00 00 00 00 8a db ca

-------------------------------------------------------------------------------
090-03861-03   serial number W5609120082   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]                         
                                              TFOM     9             FFOM     3
                                              UCCM-P Status[OCXO WARMUP]
                                             
>> GPS: [no ref]                             
ACQUISITION .............................................. [ GPS 1PPS Invalid ]
Tracking: 0 ____   Not Tracking: 0 ________   Time ____________________________
                                              GPS      00:00:43 [?] 06 JAN 1980
c5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 00 00 00 2a 00 00 41 00 8f 50 00 00 00 00 7c 19 ca
                                              GPS      Invalid: not tracking
                                              ANT DLY  +0.000E+00
                                              Position ________________________
                                              MODE     Survey:      0% complete
                                                       Suspended: track <4 sats
                                              INIT LAT N  34:44:00.000
                                              INIT LON E 135:21:00.000
                                              INIT HGT           +0.00 m  (MSL)
                                             
                                             
                                             
                                             
ELEV MASK  5 deg                             
-------------------------------------------------------------------------------

Command Complete
UCCM-P > c5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 00 00 00 2c 00 00 41 00 8f 50 00 00 00 00 77 7e ca
TODc5 00 80 00 00 00 00 28 1c 52 00 00 20 60 c1 91 00 00 00 00 00 00 00 00 00 00 00 00 00 00 2e 00 00 41 00 8f 50 00 00 00 00 81 bc ca
 DI
Command Complete
UCCM-P >

After issuing TOD EN you can see I am typing in SYST:STAT? and it getting garbled amongst the timestamps, however this is just fine - no undefined header errors.

I also timed it so when I pressed enter I would get the TOD message in the normal output of SYST:STAT? which can clearly be seen. I then turned off timestamps with the TOD DI command and it was interrupted but the command completed with no undefined header errors.

I can't say I've noticed skipped time stamps but I haven't been looking for them anyway.

Well done on your progress with Lady Heather though. I hear she can be a cruel mistress (groan)  :-+
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 03, 2016, 04:34:26 pm
Lady Heather uses the time stamp message to pace / trigger sending requests for info from the receiver.  Whenever a time stamp message arrives, I send a few queries to the receiver from a queue of pending info request messages.  I suspect that the reason I am not seeing time stamps arrive in the middle of query results is because my requests are always done right after a time stamp message arrives.  As long as all the results come back within 2 seconds, I will never see a time stamp arrive in the middle of a response from the receiver.

The "Undefined header" response that I see whenever a time stamp arrives in the middle of sending a query to the receiver is probably an artifact of the way that Heather queues up and sends requests to the unit.   They don't occur very often and the info will be re-requested on the next message polling cycle.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 04, 2016, 03:59:23 pm
I've done several self-surveys with the Symmetricom unit and it consistently reports an altitude that is around 30 meters above the WGS84 altitude (I know my antenna location to within a centimeter).   The geoid-ellipsoid separation at my location is 27.3 meters.  It sure looks like it is reporting the altitude in MSL (mean sea level), not WGS84 coordinates.  So, if you manually set the survey location send it MSL altitude and not the WGS84 altitude that most GPS receivers report.

I need to run the Trimble unit some and see if it does the same thing.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on July 04, 2016, 04:21:26 pm
I've done several self-surveys with the Symmetricom unit and it consistently reports an altitude that is around 30 meters above the WGS84 altitude (I know my antenna location to within a centimeter).   The geoid-ellipsoid separation at my location is 27.3 meters.  It sure looks like it is reporting the altitude in MSL (mean sea level), not WGS84 coordinates.  So, if you manually set the survey location send it MSL altitude and not the WGS84 altitude that most GPS receivers report.

I need to run the Trimble unit some and see if it does the same thing.

Hi

But do you *really* know any altitude to within a centimeter from day to day?  :scared: :scared: :scared:

http://www.navipedia.net/index.php/Solid_Tides (http://www.navipedia.net/index.php/Solid_Tides)

Now if only there was a program out there that displayed that .... Yes, you *must* include the gravitational impact of Pluto to get "all the details" .... :scared: :scared:

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 04, 2016, 05:06:25 pm
I think I figured out why I get an "Undefined header" response if a time code message comes out in the middle of sending a command to the unit...  the unit stops accepting and echoing input characters while the time code is coming out (which takes around 25 milliseconds).  I suspect that it also blocks input while it is sending responses to any query, but the way that Lady Heather works prevents that from happening... only those unsolicited time code messages cause the queries being sent to the unit to get garbled. 

I've only seen queries sent right after the rather long DIAG:LOOP? response comes in getting munged.  I suspect that a query sent after a SYST:STAT? message arrives could also be munged, but Heather only sends that query once a minute (at xx:xx:33 seconds).
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on July 04, 2016, 05:33:57 pm
I think I figured out why I get an "Undefined header" response if a time code message comes out in the middle of sending a command to the unit...  the unit stops accepting and echoing input characters while the time code is coming out (which takes around 25 milliseconds).  I suspect that it also blocks input while it is sending responses to any query, but the way that Lady Heather works prevents that from happening... only those unsolicited time code messages cause the queries being sent to the unit to get garbled. 

I've only seen queries sent right after the rather long DIAG:LOOP? response comes in getting munged.  I suspect that a query sent after a SYST:STAT? message arrives could also be munged, but Heather only sends that query once a minute (at xx:xx:33 seconds).

Hi

It could be a bug or there may be a magic "required hold off" period to either side of the time code message.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 04, 2016, 05:57:30 pm
It could be a bug or there may be a magic "required hold off" period to either side of the time code message.

I've tried putting in delays after a time code message comes in before sending anything to the receiver, but it made no difference.   A gotcha is that Heather sends messages to the receiver via the operating system serial port driver.  Heather sends full messages to the serial port driver,  which buffers them up and sends them out at its leisure.  There could be data pending in the OS buffers.   A "hold off" required before the time code is sent would require a binary feed-forward temporal fudger... ain't gonna happen.

I just saw a corrupted request after a SYST:STAT? message... so probably any query sent to the receiver stands a chance of being munged by a time code message... it's just that those long STAT? and LOOP? responses increase the probability of mungeosity.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on July 04, 2016, 06:04:56 pm
Hi

Simply to make the collision happen on the GPSDO end requires a bit of work. A normal buffered serial approach would make it pretty hard to do. I'd guess there is an interrupt for the pps and the time string comes entirely from the ISR. Shame shame ....(Yes, I have seen that done in code from "other unnamed vendors" ... that code is no longer written that way :)  )

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: DDalton on July 04, 2016, 07:18:40 pm
New member here. I've read this thread with great interest, because the Symmetricom board discussed here appears to be the board used inside a complete GPSDO — case, LCD, antenna and all — sold by a Chinese seller. I've had one of these devices for two or three days now, and it seems to work just as described here, though for some reason I'm having trouble connecting through its RS-232 console port.

Has anyone else explored this ready-made device? They're being sold for $209 including shipping. The seller is "radioshackus," and he has good feedback. The item's description on eBay is "Symmetricom Inside GPS 10MHz 1PPS GPS Disciplined Clock&GPS Ant Display GPSDO."

I'm attaching a couple of photos, including a photo of the box's output coupled to my HP 5355A counter.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: f1rmb on July 04, 2016, 07:31:28 pm
Hi,

New member here. I've read this thread with great interest, because the Symmetricom board discussed here appears to be the board used inside a complete GPSDO — case, LCD, antenna and all — sold by a Chinese seller. I've had one of these devices for two or three days now, and it seems to work just as described here, though for some reason I'm having trouble connecting through its RS-232 console port.

Has anyone else explored this ready-made device? They're being sold for $209 including shipping. The seller is "radioshackus," and he has good feedback. The item's description on eBay is "Symmetricom Inside GPS 10MHz 1PPS GPS Disciplined Clock&GPS Ant Display GPSDO."

I'm attaching a couple of photos, including a photo of the box's output coupled to my HP 5355A counter.

With F4CTZ's display (Yeah, mixed lines...)  :palm:
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 04, 2016, 08:33:59 pm
I have two of the Trimble units.  One with firmware 2.0.1.6  It responds with the UCCM-P> prompt.   The other has version 3.0.0.11 and responds with the UCCM> prompt.  I have not done much digging to see if the later version has any differences in the commands (particularly undocumented ones) that it accepts.  So far they appear to function identically.

Both Trimble units report the altitude in WGS84 coordinates and are within a meter of the true value.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: shinjiikari0601 on July 05, 2016, 11:29:04 pm
Nice GPSDO. Interesting to see the similarities in the summary screens, when compared to other HP-based GPSDO's (Z38xxA's). Looks like the command set is very similar as well. It's nice that the command sets and outputs are similar... Allows one to write software that is compatible with them all, with a relatively low amount of custom coding for each unit.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 06, 2016, 12:37:02 am
Looks like the command set is very similar as well. It's nice that the command sets and outputs are similar... Allows one to write software that is compatible with them all, with a relatively low amount of custom coding for each unit.

Au contraire...  they may look similar on the surface,  but there are enough differences to be a real pain.  I wound up treating these as pretty much a different beast than the Z38xx stuff.   Lady Heather has around 1000 lines of code to talk to the Z3801A (plus a few hundred more lines of code for tweaking the screen displays and log files for the data that can be squeezed out them).   Adding support for these (UCCM)  receivers took another 700 lines. Less than 300 lines of the Z3801A code is shared with controlling the UCCM's.  (BTW, Lady Heather is around 50,000 lines of code).

None of the SCPI / UCCM based devices were designed with the intent of having a computer continuously control and monitor them.  The user interface assumes that a meat-bag techno-monkey will very occasionally pound out a few commands on the keyboard, toss a few feces around,  and check status when first installing and setting up the units... and after that the monkey will climb back into its tree and will leave them be until something goes horribly wrong and the unit needs replacing.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: shinjiikari0601 on July 06, 2016, 12:47:25 am
Looks like the command set is very similar as well. It's nice that the command sets and outputs are similar... Allows one to write software that is compatible with them all, with a relatively low amount of custom coding for each unit.

Au contraire...  they may look similar on the surface,  but there are enough differences to be a real pain.  I wound up treating these as pretty much a different beast than the Z38xx stuff.   Lady Heather has around 1000 lines of code to talk to the Z3801A (plus a few hundred more lines of code for tweaking the screen displays and log files for the data that can be squeezed out them).   Adding support for these (UCCM)  receivers took another 700 lines. Less than 300 lines of the Z3801A code is shared with controlling the UCCM's.  (BTW, Lady Heather is around 50,000 lines of code).

None of the SCPI / UCCM based devices were designed with the intent of having a computer continuously control and monitor them.  The user interface assumes that a meat-bag techno-monkey will very occasionally pound out a few commands on the keyboard, toss a few feces around,  and check status when first installing and setting up the units... and after that the monkey will climb back into its tree and will leave them be until something goes horribly wrong and the unit needs replacing.
Thanks for the clarification. I guess the surface similarities are just that, then. You are certainly correct in that the interface command sets of these units were not really made for us humans to grok manually.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 06, 2016, 12:52:27 am
Thanks for the clarification. I guess the surface similarities are just that, then. You are certainly correct in that the interface command sets of these units were not really made for us humans to grok manually.

No, they were designed for humans to (very occasionally) interact with,  not for computers to continuously control and monitor them.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on July 06, 2016, 12:53:32 am
Either these uccm modules were mounted inside a piece of equiptment(either for telecom/other form of communications). Or they were a module on their own, and that was discarded. We will never find out...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on July 06, 2016, 02:26:33 am
From what I can gather they were redundant modules used in GSM base stations/cell towers. They appear to have come from Japan looking at the on board logs.

Physically the Trimble and Symmetricom UCCM appear to be compatible. Same connectors, voltages, etc. Everything else, not quite...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on July 12, 2016, 09:19:18 pm
I got one of the Trimble units the other day. It arrived with no missing or damaged components. I inspected it under a microscope. At first thought it was dead because NONE of the status LEDs light up. However, hooking up a serial port and grabbing the status info  shows that it is indeed working correctly. It is tracking satellites and is phase locking, etc. Has anyone else seen this behavior with the Trimble versions? Could there be a software command or jumper to turn on the status LED's? Also I am supplying it with just over 6v and it is properly regulating at 5v.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: sharpgun on July 23, 2016, 05:56:57 pm
The Power Supply Connet F1 and L9, is correct? 
Connet RS232, I Selected 6V power supply,the board is UP, not connet Antenna operation errors.....


1-1. #Now ACTIVE STATUS ---------------- [Alarm]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warmup]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [LINK0]
2-4. #Current Reference Status --------- [NOT SELECTED]
     #GPS STATUS ----------------------- [Unavailable]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ 10MHZ ]
     #Bad Quality ------- [ LINK ]
3-1. PLL STATUS ------------------------ [Disable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
Command Complete

When 6.5V up
1-1. #Now ACTIVE STATUS ---------------- [OCXO Warm]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warmup]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [LINK0]
2-4. #Current Reference Status --------- [NOT SELECTED]
     #GPS STATUS ----------------------- [Unavailable]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
Command Complete


the error log
L482:1980-01-06 00:00:02:Power On
L483:1980-01-06 00:00:10:Antenna feed line fault
L484:1980-01-06 00:00:02:Power On [reset switch]
L485:1980-01-06 00:00:10:Antenna feed line fault
L486:1980-01-06 00:00:35:Survey mode started
L487:1980-01-06 00:00:02:Power On [command]
L488:1980-01-06 00:00:10:Antenna feed line fault
L489:1980-01-06 00:00:33:Survey mode started
L490:1980-01-06 00:00:02:Power On
L491:1980-01-06 00:00:03:FPGA VCXO Alarm
L492:1980-01-06 00:00:03:OCXO Alarm
L493:1980-01-06 00:00:03:Funct Fail code: 00000208
L494:1980-01-06 00:00:03:Funct Fail OCXO curr: 41 mA
L495:1980-01-06 00:00:03:Funct Fail PDOP: 0.00
L496:1980-01-06 00:00:03:Funct Fail sat count: 0
L497:1980-01-06 00:00:03:Funct Fail TRAIM: 0 0
L498:1980-01-06 00:00:29:OCXO Alarm
L499:1980-01-06 00:00:02:Power On
L500:1980-01-06 00:00:36:Survey mode started

Why the log show ‘Antenna feed line fault“?I not connecting Antenna?????the PCB Borad is not ok?

OTHER Message

UCCM-P > posstatus
-----------------------------------------------------------------------------
1/6/1980 00:05:16
-----------------------------------------------------------------------------
 Position : LAT(N 34:44:0.000) LON(E 135:21:0.000) H(0.00 m MSL)
-----------------------------------------------------------------------------
 Geometry : PDOP(0.0) HDOP(0.0) VDOP(0.0)
-----------------------------------------------------------------------------
 Channel Status
   num of visible sats > 0
   num of sats tracked > 0
   ------ Receiver Channel State ------
     CH 0 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 1 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 2 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 3 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 4 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 5 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 6 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 7 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 8 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 9 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 10 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 11 >  SateID(0) TrackMode(code search) SigValue(0)
-----------------------------------------------------------------------------
  Rcvr Status(1) :
-----------------------------------------------------------------------------
  Antenna Voltage: 5931 mV,  Antenna Current: 30 mA
-----------------------------------------------------------------------------
Command Complete


UCCM-P > SYSTem:STATus?
-------------------------------------------------------------------------------
090-03861-03   serial number W560951092   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     9             FFOM     3
                                              UCCM-P Status[OCXO WARM]

>> GPS: [no ref]
ACQUISITION .............................................. [ GPS 1PPS Invalid ]
Tracking: 0 ____   Not Tracking: 0 ________   Time ____________________________
                                              GPS      00:08:45 [?] 06 JAN 1980
                                              GPS      Invalid: not tracking
                                              ANT DLY  +0.000E+00
                                              Position ________________________
                                              MODE     Survey:      0% complete
                                                       Suspended: track <4 sats
                                              INIT LAT N  34:44:00.000
                                              INIT LON E 135:21:00.000
                                              INIT HGT           +0.00 m  (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on July 23, 2016, 06:14:08 pm
Hi

Antenna fault = coax is shorted to ground

*or*

The antenna is not pulling enough current.

Of the two, the first one is a *much* better bet. If it shows the fault with no coax connected, there is a problem with your board.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: sharpgun on July 24, 2016, 03:38:33 am
Hi

Antenna fault = coax is shorted to ground

*or*

The antenna is not pulling enough current.

Of the two, the first one is a *much* better bet. If it shows the fault with no coax connected, there is a problem with your board.

Bob

coax is not shorted to ground ......tested antenna site is +5v , 4ma....
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 24, 2016, 03:56:30 am
coax is not shorted to ground ......tested antenna site is +5v , 4ma....

4 mA is not enough to be considered as a valid antenna.   I don't know what the threshold is on these units, but on most receivers it usually at least 10-15 mA.  Try adding a resistor across the antenna lead and see if you can get a valid antenna detection.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: sharpgun on July 24, 2016, 06:29:59 am
coax is not shorted to ground ......tested antenna site is +5v , 4ma....

4 mA is not enough to be considered as a valid antenna.   I don't know what the threshold is on these units, but on most receivers it usually at least 10-15 mA.  Try adding a resistor across the antenna lead and see if you can get a valid antenna detection.

not connect antenna , 6.5V supply......
Antenna Voltage: 6127 mV,  Antenna Current: 0 mA

connect antenna ,changed
 Antenna Voltage: 5912 mV,  Antenna Current: 30 mA


UCCM-P > status

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [OCXO Warm]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warmup]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [LINK0]
2-4. #Current Reference Status --------- [NOT SELECTED]
     #GPS STATUS ----------------------- [Unavailable]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
Command Complete

Now ACTIVE STATUS    .....always display [OCXO Warm]..after a few hours, it still display [OCXO Warm]. .... buy the way,, the 10M out not send signel....
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on July 24, 2016, 11:47:38 pm
coax is not shorted to ground ......tested antenna site is +5v , 4ma....

4 mA is not enough to be considered as a valid antenna.   I don't know what the threshold is on these units, but on most receivers it usually at least 10-15 mA.  Try adding a resistor across the antenna lead and see if you can get a valid antenna detection.

not connect antenna , 6.5V supply......
Antenna Voltage: 6127 mV,  Antenna Current: 0 mA

connect antenna ,changed
 Antenna Voltage: 5912 mV,  Antenna Current: 30 mA


UCCM-P > status

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [OCXO Warm]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warmup]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [LINK0]
2-4. #Current Reference Status --------- [NOT SELECTED]
     #GPS STATUS ----------------------- [Unavailable]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
Command Complete

Now ACTIVE STATUS    .....always display [OCXO Warm]..after a few hours, it still display [OCXO Warm]. .... buy the way,, the 10M out not send signel....

Hi

Looks like it's not getting what it wants when it talks to the GPS.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: sharpgun on July 25, 2016, 07:04:27 am
coax is not shorted to ground ......tested antenna site is +5v , 4ma....

4 mA is not enough to be considered as a valid antenna.   I don't know what the threshold is on these units, but on most receivers it usually at least 10-15 mA.  Try adding a resistor across the antenna lead and see if you can get a valid antenna detection.

not connect antenna , 6.5V supply......
Antenna Voltage: 6127 mV,  Antenna Current: 0 mA

connect antenna ,changed
 Antenna Voltage: 5912 mV,  Antenna Current: 30 mA


UCCM-P > status

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [OCXO Warm]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warmup]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [LINK0]
2-4. #Current Reference Status --------- [NOT SELECTED]
     #GPS STATUS ----------------------- [Unavailable]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
Command Complete

Now ACTIVE STATUS    .....always display [OCXO Warm]..after a few hours, it still display [OCXO Warm]. .... buy the way,, the 10M out not send signel....

Hi

Looks like it's not getting what it wants when it talks to the GPS.

Bob


THANK YOU  ... I changed the GPS Antenna, the GPS moudle is OK.......BUT OCXO not LOCK...Always Warm...... the error display
2016-07-25 07:03:54:Near EFC Sat Alarm : 0%

I will test the OCXO Voltage later..... the OCXO power Supply is +5v or +12v  ????

Show you the Message..
UCCM-P > system:status?
-------------------------------------------------------------------------------
090-03861-03   serial number W560951092   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     9             FFOM     3
                                              UCCM-P Status[OCXO WARM]

>> GPS: [phase: -1.36e-04, adjusting freq]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 5 ____   Not Tracking: 6 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      07:01:53     25 JUL 2016
  2  13 248   32     1   8  45                GPS      Synchronized to UTC
  3  37  56   46     6  47 271                ANT DLY  +0.000E+00
 17  47 353   39     9   7 137                Position ________________________
 22  17  45   39    19  34 323                MODE     Survey:    1.5% complete
 28  82 147   39    23   6 111
                    30  15 190                AVG LAT  N  22:31:43.008
                                              AVG LON  E 114:01:20.434
                                              AVG HGT          +201.18 m  (MSL)




ELEV MASK  5 deg


Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: sharpgun on July 25, 2016, 07:31:35 am
Power Supply 6.5v .....the OCXO test Voltage is
1. Power  5.77
2. VRef 2.80
3. EFC 2.80

is OK?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on July 25, 2016, 11:45:31 am
Power Supply 6.5v .....the OCXO test Voltage is
1. Power  5.77
2. VRef 2.80
3. EFC 2.80

is OK?

Hi

Nobody really knows what the right supply voltage is. 5V seems to be a common voltage to use. I suspect there is a tolerance on the supply like +/- 0.5V. Your EFC is "railed" to the Vref supply. That suggests that either the OCXO is broken or the disciplining part of the module has a problem.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on July 25, 2016, 02:03:36 pm
If the power pin of the ocxo is that low, than the dc-dc converter is broke, ocxo needs 12.0v .
Have you been feeding the module 5ish Volts, and around 2A.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: deepskyridge on July 25, 2016, 02:39:28 pm
I have one of the Trimble UCCM boards up and running.

UCCM-P >STATUS

               - UCCM Slot STATE-

1-1. #Now ACTIVE STATUS ---------------- [OCXO Warm]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warm]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [GPS]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL [ LINK ]
     #OPERATION ALARM ------------------ [LINK ]
3-1. #PLL STATUS ----------------------- [DISABLE]
3-2. #Current PLL MODE ----------------- [OFFSET OBSERVATION MODE]

Is there a way to set the #Priority Level to GPS > LINK ? I have not found it, (I did search this thread)

Also what does the #Current PLL Mode signify ?

Thanks
Gary
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ZigmundRat on July 25, 2016, 02:53:12 pm
Congratulations on having a functioning unit :)

A while back I posted:

A couple tips for improving the operation of these units (at least the Symmetricom ones). Power up the unit and let it do it's survey and get all nice and stable. (Make sure SYST:STAT? shows Position MODE Hold). Then issue a GPS:POS:HOLD:LAST? command. The output will be your position:

UCCM-P > GPS:POSition:HOLD:LAST?
N,+42,+34,+3.40880E+01,W,+74,+39,+2.72220E+01,+1.10340E+02
Command Complete
UCCM-P >

The output is conveniently in the form used to manually set the position. Use these values in the future to skip the survey. We will also want to set some other parameters to optimize the operation. What you do is send the UCCM a series of initialization strings. I've posted the ones I use below. Send them with a terminal program, a micro-controller, whatever.

SYNC:REF:DISABLE LINK
SYNC:REF:ENABLE GPS
REF:TYPE GPS
OUTP:TP:SEL PP1S
GPS:SAT:TRAC:EMAN 20
GPS:POS N,+42,+34,+3.40880E+01,W,+74,+39,+2.72220E+01,+1.10340E+02

What all this does is turns off the other timing sources (which are unconnected but could still have influence) and using only GPS. It also makes sure the PPS output is 1 PPS and not 1 PP2S (1 per 2 seconds). The satellite elevation mask is change to 20 degrees to avoid multipath and other anomalies from satellites near the horizon. This improves the timing and frequency stability. Finally we set our position, which will skip the auto survey. Note that it doesn't seem to really like slamming the commands in. So wait for the UCCM prompt to come back before sending the next command.

My unit has been baking in for a while, so I'll be doing another stability run shortly. Hopefully the ADEV will be better after the OCXO has cooked for a couple months.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: sharpgun on July 25, 2016, 03:06:34 pm
Power Supply 6.5v .....the OCXO test Voltage is
1. Power  5.77
2. VRef 2.80
3. EFC 2.80

is OK?

Hi

Nobody really knows what the right supply voltage is. 5V seems to be a common voltage to use. I suspect there is a tolerance on the supply like +/- 0.5V. Your EFC is "railed" to the Vref supply. That suggests that either the OCXO is broken or the disciplining part of the module has a problem.

Bob

I Test the pcb , When the board SUPPLY +12V, OCXO power is 11.x V ,10m output signel is close to 10M....... the  VRef 5.40V...and EFC 2.x V ..... I Think the OCXO and EFC is OK.......    Whice part Transformer 5V to 12V ..... L2 ?????
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ZigmundRat on July 25, 2016, 03:11:19 pm
If the power pin of the ocxo is that low, than the dc-dc converter is broke, ocxo needs 12.0v .
Have you been feeding the module 5ish Volts, and around 2A.

I don't have a Trimble unit, but it's my understanding the Trimble units use a 5V OCXO. Do NOT feed the Trimble boards 12v. All of these UCCM boards should be fed 6V. The Symmetricom units have a 12v OCXO and a DC-DC converter to supply it, the Trimble units just use a 5V OCXO.

The being said, if EFC = Vref it's not a good sign. But let it warm up and complete the survey (give it 2 hours or so). Then let's see the last 10-20 lines of the DIAGnostic:LOG:READ:ALL? output and status commands.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on July 25, 2016, 03:44:43 pm
Yea, Trimble unit I have, has a 6.8V zener diode across the input. Putting more voltage than this on the input will smoke the diode. I run it at about 6v. The Symmetricom module works fine with 5v.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: deepskyridge on July 25, 2016, 05:54:57 pm
Congratulations on having a functioning unit :)

A while back I posted:

A couple tips for improving the operation of these units (at least the Symmetricom ones). Power up the unit and let it do it's survey and get all nice and stable. (Make sure SYST:STAT? shows Position MODE Hold). Then issue a GPS:POS:HOLD:LAST? command. The output will be your position:

UCCM-P > GPS:POSition:HOLD:LAST?
N,+42,+34,+3.40880E+01,W,+74,+39,+2.72220E+01,+1.10340E+02
Command Complete
UCCM-P >

The output is conveniently in the form used to manually set the position. Use these values in the future to skip the survey. We will also want to set some other parameters to optimize the operation. What you do is send the UCCM a series of initialization strings. I've posted the ones I use below. Send them with a terminal program, a micro-controller, whatever.

SYNC:REF:DISABLE LINK
SYNC:REF:ENABLE GPS
REF:TYPE GPS
OUTP:TP:SEL PP1S
GPS:SAT:TRAC:EMAN 20
GPS:POS N,+42,+34,+3.40880E+01,W,+74,+39,+2.72220E+01,+1.10340E+02

What all this does is turns off the other timing sources (which are unconnected but could still have influence) and using only GPS. It also makes sure the PPS output is 1 PPS and not 1 PP2S (1 per 2 seconds). The satellite elevation mask is change to 20 degrees to avoid multipath and other anomalies from satellites near the horizon. This improves the timing and frequency stability. Finally we set our position, which will skip the auto survey. Note that it doesn't seem to really like slamming the commands in. So wait for the UCCM prompt to come back before sending the next command.

My unit has been baking in for a while, so I'll be doing another stability run shortly. Hopefully the ADEV will be better after the OCXO has cooked for a couple months.

Hi, I did use you post awhile back to set these parameters.

I was wondering about:

#Priority Level ------------------- [LINK > GPS]
#PLL STATUS ----------------------- [DISABLE]
#Current PLL MODE ----------------- [OFFSET OBSERVATION MODE]

I have not found any reference to these.

Thanks
Gary
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: sharpgun on July 26, 2016, 12:25:52 pm
I  Checked the PTN04050C ,it is work not correctly......When I supply 6.5V... the PTN04050C output 6.4V........so the OCXO always warm.... the board not work normal.......
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: deepskyridge on July 26, 2016, 10:31:23 pm
I have a Trimble UCCM module, does anyone know if this unit uses TSIP or NEMA for communications with the main board.?

I know the Symmetricon unit uses NEMA.

Thanks
Gary
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 26, 2016, 10:32:56 pm
I have a Trimble UCCM module, does anyone know if this unit uses TSIP or NEMA for communications with the main board.?

They use the same receiver, so NMEA only.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on July 26, 2016, 11:41:12 pm
I  Checked the PTN04050C ,it is work not correctly......When I supply 6.5V... the PTN04050C output 6.4V........so the OCXO always warm.... the board not work normal.......
6.5V is too much. You should run it on 5V, maybe up to 5.5V to take into account cable losses from your PSU at high current. You will also find that your antenna voltage is directly fed from the unregulated 5V input (less a diode drop) and so you risk that too as most antennas are rated <=5V

I had the same problem with a faulty PTN04050C. Despite them being sold on AliExpress they were way to expensive (like £20) so I used a cheap boost module XL6009 for 99p instead ;)

Finally, I can not get this to start up properly with a Rigol DP832 no matter how high I set the current. Other supplies are ok but only if I set the current to over 1.6A.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: sharpgun on July 27, 2016, 09:06:48 am
I  Checked the PTN04050C ,it is work not correctly......When I supply 6.5V... the PTN04050C output 6.4V........so the OCXO always warm.... the board not work normal.......
6.5V is too much. You should run it on 5V, maybe up to 5.5V to take into account cable losses from your PSU at high current. You will also find that your antenna voltage is directly fed from the unregulated 5V input (less a diode drop) and so you risk that too as most antennas are rated <=5V

I had the same problem with a faulty PTN04050C. Despite them being sold on AliExpress they were way to expensive (like £20) so I used a cheap boost module XL6009 for 99p instead ;)

Finally, I can not get this to start up properly with a Rigol DP832 no matter how high I set the current. Other supplies are ok but only if I set the current to over 1.6A.


I have changed Supply Power, remove PTN04050C, the Power supply both +5V and +12........the board is run correctly....GPS is locked.....
Thank you for all the people who helped me....
  - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [Master]
1-2. #Before ACTIVE STATUS ------------- [Master Holdover]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [NORMAL 2 MODE]
Command Complete


UCCM-P > system:status?
-------------------------------------------------------------------------------
090-03861-03   serial number W560951092   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     2             FFOM     0
                                              UCCM-P Status[ACTIVE]

>> GPS: [phase:  2.23e-08]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 7 ____   Not Tracking: 2 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      09:05:43     27 JUL 2016
  2  37 308   37    12  24 309                GPS      Synchronized to UTC
  5  30 225   42    28  16 169                ANT DLY  +0.000E+00
  6  47   7   45                              Position ________________________
  9  27  78   41                              MODE     Survey:   16.4% complete
 17  53  98   45
 19  65  53   44                              AVG LAT  N  22:31:39.502
 23  12  55   39                              AVG LON  E 114:01:18.520
                                              AVG HGT           +42.56 m  (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------

Command Complete


L95:1980-01-06 00:00:02:Power On [command]
L96:1980-01-06 00:00:33:Survey mode started
L97:1980-01-06 00:00:57:PDOP too high
L98:1980-01-06 00:01:30:PDOP too high
L99:1980-01-06 00:01:53:Time set to GPS
L100:2016-07-27 08:45:53:Time set to GPS
L101:2016-07-27 08:47:00:GPS lock started

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on July 27, 2016, 04:36:22 pm
Well two and half months later, becuse of the dear customs, i got today my GPS antenna, connected to the board and all went well, made the board anly receiving from the GPS, taking out the 'LINK' part.

Now to find to find one box, to fit all in.

GPSDO is now connected to the HP53181, the 53181 is running is internal oscilator, not the OCXO, source is set to Auto, GPSDO plug in to CH1, gate at .300s, DC coupled, 50Ohm, reading 10.000.015.150Hz, I'll leave the GPSDO running for some time and then maybe adjust the internal oscilator of the 53181, and set the source to external.

 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: deepskyridge on July 27, 2016, 05:02:29 pm
I have a Trimble UCCM module, does anyone know if this unit uses TSIP or NEMA for communications with the main board.?

They use the same receiver, so NMEA only.

Thanks, do you know where on the board the NEMA output is located ?

Thanks
Gary
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on July 27, 2016, 09:12:43 pm

Thanks, do you know where on the board the NEMA output is located ?


Earlier in this thread is a lot of discussion on taping into the NMEA stream of the receiver.  But most of the data is Furuno specific.  There is also a link to the Furuno manual.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: deepskyridge on August 02, 2016, 03:33:05 am
I have Lady Heather working pretty well with my Trimble unit. 

I added some code to poll and read the DIAG:LOOP? message.  The main value that seems interesting is the FREQ DIFF value.  I log and plot that as the "OSC" parameter.   It is 0.0 if the unit is not discipling the oscillator (power-up, user turned off disciplining by setting a fixed DAC value, etc).   

Occasionally the FREQ DIFF has a bogus value -2.79E-07.  I treat this as noise and ignore that reading.   One very interesting thing that I noticed is than once an hour (at xx:26:26) the loop goes a bit whacky.  It looks like the firmware does something that upsets / resets / whatever-sets the PLL.   Attached is a plot of the resulting havoc...  It takes around 3 minutes for the loop to start settling down,  but takes around 18 minutes to stabilize and 36 minutes to really dampen out... only to have it's bell rung 24 minutes after that.

Any date for when Lady Heather will be ready for primetime. ?

Thanks
Gary
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on August 02, 2016, 04:18:42 pm
Does any of you guys know what is the use of the PULLINRANGE? command.

I have type it and got the replay, [30ppb] Command Complet.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on August 03, 2016, 03:18:15 pm
For those that are thinking of buying or making an distribution amplifier for 10MHz, look at this video from Gerry https://youtu.be/chrzrod3tQY, (https://youtu.be/chrzrod3tQY,) or this other guy that use a smaller version http://www.jackenhack.com/reference-10-mhz-distribution-amplifier/, (http://www.jackenhack.com/reference-10-mhz-distribution-amplifier/,) any of them will be ok, and the box has lot of free space inside for an Arduino, GPSDO, LCD, Raspberry.

I've here one box but is already drill for another project, so instead of buying a new box, will buy one/two of this and make all the connections inside this box.

Since this bug bite me, I went ahead and bought an Trimble board to make another one.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: sharpgun on August 07, 2016, 04:46:24 am
 O0Hi, anybody know how to connect to GPS GT-8031F? Whice Pin is RX TX.... TTL or  RS232..............Show me the Picture....3Q
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on August 07, 2016, 06:33:43 pm
If you´re talking about the Furuno GPS, witch is locate under the board near the GPS antenna connector, this is TTL level, somewhere around page 10 to 17 is the assignmentof this pins, the square pin is #1 all the above on the same side are 3, 5, 7, etc, on the other side is 2, 4, 6, etc.

The only RS-232 connector is the plug with 4 pins on top off the board, near the main connector.

 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: sharpgun on August 08, 2016, 06:05:54 am
If you´re talking about the Furuno GPS, witch is locate under the board near the GPS antenna connector, this is TTL level, somewhere around page 10 to 17 is the assignmentof this pins, the square pin is #1 all the above on the same side are 3, 5, 7, etc, on the other side is 2, 4, 6, etc.

The only RS-232 connector is the plug with 4 pins on top off the board, near the main connector.



yes, I talked about Furnno GPS, when I connect link this (RS232 and TTL)
GT-8031F                 Computer COM
Pin 3 TX                     RX
Pin 4 RX                     TX
Pin 8 GND                  GND

the computer is not display message(9600bps and any).....

I want direct connecting to the GPS, no successful
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on August 08, 2016, 08:17:52 am
For connecting the Furuno GPS to the PC you need an TTL to RS-232 converter.
You can´t talk to the Furuno GPS, only listen the NMEA talk.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on August 10, 2016, 09:43:49 am
I'm still waiting for the boxes to arrive here, for the enclosure of the GPSDO, Arduino, TFT and amplifier plus the 1PPS output.
Meantime I've bought one unit of the Trimble on fleabag, waiting to arrive.

On the UCCM I notice that the command DIAG:ROSC:EFC:DATA? this value is the same number of the value present with DIAG:LOOP? on the GPS line NCO column, and both are the round number of the freq corr line in the same DIAG:LOOP?

 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: jkf1000 on September 01, 2016, 09:56:02 am
What a fantastic thread,
 Nuno, congratulations on having an operational unit after waiting so long for your antenna, I know customs clearance can be a pain in the rear. You must have the patience of a saint, I know I would have just ordered another one while waiting that long just to confirm that everything is working.

I recently purchased one of the Trimble units which thankfully arrived in good condition and very clean. The sellers name is Flyxy2015 but there will be hundreds of alias out there. It sounds like I may have been a little lucky given some of the horror stories I have read in this thread.

My intended use for mine is as a lab standard with all test equipment connected via a distribution unit. While waiting for the Trimble to be delivered I managed to get hold of a video distribution unit similar to the one in the projects listed above. Unfortunately the internal layout is very different to the others with each row of outputs being mounted on individual circuit boards and the Sync distribution board which is combined with the power supply board located at the bottom of the unit, so internal space is not as good as some of the others. I have made a few drastic changes to the PSU/Sync distribution board with a hacksaw :-DD

The internal PSU is thankfully an old school linear type so no issues with switching noise. I will post pictures when I am next in there.

I have a question regarding powering the Trimble. I can power mine from the bench supply with as little as 5.5v and 2.5A current limit, but that is the voltage set at the supply and not taking into account cable/connection losses. When measured at the Trimble input the voltage is between 5.2-5.3v. Has anyone tried to used a standard 5v 3A switching supply with these. I have noticed that there is usually a V adjust pot on the supply so can it be adjusted to maybe 5.4 or 5.5v. The other option is to reconfigure the switcher to a higher voltage at a component level.

Probably lots more questions as I go on so will update the thread with any progress.. Karl
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: davebb on September 01, 2016, 11:59:03 am
Hi if you find the output is low on your Trimble
Look at my posts as I found there is a solder blob that you can remove.
Dave
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: jkf1000 on September 01, 2016, 12:08:57 pm
One of the first things I checked. output is just over 3v PP high impedance and around 1.8v into 50ohms so very happy with the output level. The distribution unit I am modifying to 50ohm just gives unity gain buffered outputs to 12 separate BNC connectors. I have not noticed a drop in output no matter how many devices are connected so far, and a nice jitter free sine wave on all outputs so all looking good so far, just need power for the Trimble.. Karl
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on September 01, 2016, 12:23:26 pm
I'm just waiting for an 5V 3A wallwart, 3.2" TFT, and some 50OHm resistor to change, and I'm almost done with this project.
Since I don't have an Oscilloscope I can't check the sinewave or the Vpp into 50OHm.

Next already on the bench is an K3NG rotor, still waiting for some parts.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: jkf1000 on September 01, 2016, 12:45:37 pm
I did think about adding a display to mine, but in the end I considered it a bit of information overload. I have moved the status LEDs to the plain front panel for easy monitoring, and I will fit a DB9 RS232 connector to the front for when or if I need more status information. The intention is to leave it powered 24/7 so as long as it keeps flashing then I know it is working. The only extra I may add to the front panel is a power switch for the distribution board given that it has its own linear power supply. No point in it running when not required.
I will post more pictures of what I have so far later this evening.. Karl
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on September 01, 2016, 12:53:35 pm
I add in mine distribution amplifier, a fuse and an OFF/ON switch in the back.
The linear PSU was left, I add an linear PSU 12V 800mA for the arduino and TFT, now just miss the 5V 3A for the GPSDO.
I'll move the status led's from the board to the front panel.
I like the information on the display, this is to be running 24/7 all the package.

Now just need to find a way to print white letters on black paper.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: dl2sba on September 01, 2016, 03:15:41 pm
Hi Everbody

I'm running a Symmetricom 090-03861-03 since some days now. Where can I find detailled information on these status values:

Why is the frequency correction value slightly but constantly rising, while the phase values stay more or less flat?

I've plotted them for some days - check http://dl2sba.com/index.php?option=com_content&view=article&id=268:measurement-on-gpsdo&catid=15:shack&Itemid=27 (http://dl2sba.com/index.php?option=com_content&view=article&id=268:measurement-on-gpsdo&catid=15:shack&Itemid=27)


//Dietmar
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on September 01, 2016, 03:31:38 pm
Hi Everbody

I'm running a Symmetricom 090-03861-03 since some days now. Where can I find detailled information on these status values:
  • frequency correction
  • temperature correction
  • phase corrections
  • gps phase correction

Why is the frequency correction value slightly but constantly rising, while the phase values stay more or less flat?

I've plotted them for some days - check http://dl2sba.com/index.php?option=com_content&view=article&id=268:measurement-on-gpsdo&catid=15:shack&Itemid=27 (http://dl2sba.com/index.php?option=com_content&view=article&id=268:measurement-on-gpsdo&catid=15:shack&Itemid=27)


//Dietmar

Hi

The GPSDO acts as a PLL once things settle out. The phase is locked so it's not going to go anywhere. The frequency change shows up in the DAC values.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: dl2sba on September 01, 2016, 04:08:39 pm
Hi Bob

thanks for reply - but I don't understand completely - when the frequency correction still increments, did this mean, that the output frequency is constantly increasing/decreasing or is this the ageing of the oscillator?!

 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on September 01, 2016, 04:20:04 pm
Hi Bob

thanks for reply - but I don't understand completely - when the frequency correction still increments, did this mean, that the output frequency is constantly increasing/decreasing or is this the ageing of the oscillator?!

Hi

Yes, the DAC is stepping to keep the OCXO on frequency.

As the OCXO comes out of storage and begins to operate it will "retrace". Generally this is a one way (frequency up or frequency down) process. The amount of frequency change is generally much greater than the aging rate of the OCXO. It will settle out in a few days to a few months. It is always best to keep an OCXO on power all the time. That eliminates this effect.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: dl2sba on September 01, 2016, 04:44:07 pm
OK Bob

thanks for the information - I'll keep the GPSDO running and collect the data ... lets see how it works in longer terms ...

//Dietmar
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: jkf1000 on September 01, 2016, 08:43:57 pm
Just a few pics of my distribution project so far. Photo 1 shows how the origional lower board was modified (butchered) to retain just the origional power supply circuitry and to accomodate moving the distribution boards down into the lower two positions. The distribution boards have been reconfigured for 50ohm impedance and when tested give a nice buffered unity gain sine wave output at around 1.8v P to P on all of the output BNC connectors no matter how many loads are connected.

The rest of the photos are just various stages of the project so far. As previously stated it is just missing PSU for the trimble, mains switch to enable switch off of the analog circuits when not required and a DB9 for the RS232.

Any thoughts or suggestions very much appreciated.. Karl
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: jkf1000 on September 01, 2016, 08:45:21 pm
Rest of the photos so far.. Also forgot to mention a couple of changes I made which can be seen in the photos. Repositioning of one of the PSU filter caps to gain a little more space and the addition of a 4 pin header for the RS232 connection.. Karl
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ttipok on September 02, 2016, 11:14:03 pm
Here is pinouts of 50-pin connector of both Symmetricom/Trimble UCCM.

I did some analyzing of debugging flags, avaliable on UART-debug port (called UART3). Also High-speed serial port is found (UART4). It sending time immediatly and synchronized with 1PPS edge.
More info at http://tipok.org.ua/node/53 (http://tipok.org.ua/node/53)
Hope it will be useful.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: jkf1000 on September 03, 2016, 01:34:29 pm
Very useful information, all I need now is a consolidated list of all the serial commands if anyone has compiled it, I have quite a few which I have collected while reading through this thread but then someone else always finds more!! I have tried the UCCM- "?" but get no responce back..
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on September 03, 2016, 04:20:32 pm
Here is pinouts of 50-pin connector of both Symmetricom/Trimble UCCM.

I did some analyzing of debugging flags, avaliable on UART-debug port (called UART3). Also High-speed serial port is found (UART4). It sending time immediatly and synchronized with 1PPS edge.
More info at http://tipok.org.ua/node/53 (http://tipok.org.ua/node/53)
Hope it will be useful.
Excellent work. Shame about that high speed UART4 not having the leap second byte. But did you check if it may be adding the leap second automatically so no need for the separate byte itself? The flag is there to let you know it's got it. It would seem odd not to incorporate leap seconds in some manner yet provide the flag?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ttipok on September 04, 2016, 10:28:59 am
Just checked-out once more. There is no leap seconds addition on this port. Just raw GPS time. But, as work-around, there is flags transferred as well so from this flags we can determine that receiver got leap seconds amount and read them from another port (binary debug UART3).
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on September 05, 2016, 08:27:52 am
Bit 1 (0x02) in the FL[0] word appears to be the leapsecond pending flag.  Back in June, before the leapsecond announcement it was always 0.  Now it is 1.

Edited to correct the bit number/mask...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ttipok on September 05, 2016, 08:19:33 pm
Yep, You are right, but seems like it's FL[0] bit1, if taking into account this (http://abelian.org/vlf/tmp/notes-57963.txt) and this (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg967799/#msg967799) logs.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on September 05, 2016, 10:38:47 pm
Yep, You are right, but seems like it's FL[0] bit1, if taking into account this (http://abelian.org/vlf/tmp/notes-57963.txt) and this (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg967799/#msg967799) logs.

Oops,  I was working off my re-formatted log dump and not my actual code...

FL0 went from 0x60 pre-leapsecond announcement to 0x62 afterwards.

BTW, if you have a Z3801A, it says the leapsecond will happen on Sept 30 and not Dec 31.  Also, sometime in the last couple of weeks, lots of them have GPS receivers that hit the GPS week rollover point and started reporting it was 1997.  Lady Heather automatically detected that anomaly and corrected the date by adding 1024 weeks to the time.  Thunderbolts will hit the rollover point in the middle of 2017.

   
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 07, 2016, 06:30:43 am
All:

Would appreciate some help. Needed to resolder some new connections to the RS232 header pins and something must have messed up the unit. It keeps reporting a GPS engine failure. Not sure if it was stray electricity, static, but at a loss where to go from here. Have tried to enter a location manually, no luck. I am certain the antenna is ok. Looked over the board with a loupe in the event I broke a component off, but can not find anything. Everything responds fine using a terminal program.

Code: [Select]
UCCM-P > system:status?
-------------------------------------------------------------------------------
090-03861-03   serial number W561020383   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     9             FFOM     3
                                              UCCM-P Status[OCXO WARM]

>> GPS: [no ref]
ACQUISITION .............................................. [ GPS 1PPS Invalid ]
Tracking: 0 ____   Not Tracking: 0 ________   Time ____________________________
                                              GPS      00:27:45 [?] 06 JAN 1980
                                              GPS      Invalid: GPS rcvr failed
                                              ANT DLY  +0.000E+00
                                              Position ________________________
                                              MODE     Survey:      0% complete
                                                       Suspended: no track data
                                              INIT LAT     0:00:00.000
                                              INIT LON     0:00:00.000
                                              INIT HGT           +0.00 m  (GPS)




ELEV MASK  0 deg
-------------------------------------------------------------------------------

Code: [Select]
UCCM-P > posstatus
-----------------------------------------------------------------------------
1/6/1980 00:35:46
-----------------------------------------------------------------------------
 Position : LAT( LON( H(0.00 m MSL)
-----------------------------------------------------------------------------
 Geometry : PDOP(0.0) HDOP(0.0) VDOP(0.0)
-----------------------------------------------------------------------------
 Channel Status
   num of visible sats > 0
   num of sats tracked > 0
   ------ Receiver Channel State ------
     CH 0 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 1 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 2 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 3 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 4 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 5 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 6 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 7 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 8 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 9 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 10 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 11 >  SateID(0) TrackMode(code search) SigValue(0)
-----------------------------------------------------------------------------
  Rcvr Status(0) :
-----------------------------------------------------------------------------
  Antenna Voltage: 4637 mV,  Antenna Current: 17 mA
-----------------------------------------------------------------------------

Code: [Select]
UCCM-P > status

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [OCXO Warm]
1-2. #Before ACTIVE STATUS ------------- [Wait for GPS]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [LINK0]
2-4. #Current Reference Status --------- [NOT SELECTED]
     #GPS STATUS ----------------------- [Unavailable]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ GPS_COMM ]
     #Bad Quality ------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
Command Complete

Code: [Select]
UCCM-P > GPS:SATellite:TRACking?
"Data corrupt or stale"
UCCM-P >

Code: [Select]
UCCM-P > DIAGnostic:LOG:READ:ALL?
Log status: 4 entries

L1:1980-01-06 00:27:05:Log cleared
L2:1980-01-06 00:27:05:SYST:PRESET performed
L3:1980-01-06 00:00:02:Power On
L4:1980-01-06 00:00:17:GPS Engine Alarm
Command Complete
UCCM-P >
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 07, 2016, 07:25:42 am
Hmm, just occurred to me, if I check the output of the GPS pin 3(tx) and it is spitting out NMEA like messages than that should confirm the receiver is ok?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on September 07, 2016, 02:51:10 pm
Hmm, just occurred to me, if I check the output of the GPS pin 3(tx) and it is spitting out NMEA like messages than that should confirm the receiver is ok?
I was going to suggest just that!
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 08, 2016, 05:45:53 am
No NMEA output from pin 3 on the Furuno receiver. Soldered the receiver off the GPSDO board, but haven't had time to test the receiver yet. Did manage to find a users manual on K04BB's site. One thing I did notice when checking the voltages on the Symmetricom board is the voltage to the receivers antenna preamp (pin 10) is 4.7v, yet 5v almost everywhere else on the board. I think it should be closer to 5v, something maybe dragging it down, but it's difficult to trace back as it appears to be a multilayer board. Although I do note that there is supposed to be a 15 ohm current detection resistor across the antenna so perhaps that accounts for the voltage drop. The 3.3 supply to the receiver is a correct 3.3v. Beginning to think it's the Furuno receiver that is toast.

Just to confirm what voltages do other owners see from running the posstatus? command
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on September 08, 2016, 11:59:31 am
That's normal with the antenna voltage. It's the CR1 Rectifier causing the voltage drop.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on September 08, 2016, 12:18:10 pm
When the GPSDO starts it initialises the GPS receiver, you should be able to observe that via the pins.  If you can't see that initialisation sequence then it is getting lost somewhere... I would suspect something has fallen off

You can listen to both pin 3 and 4 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg905470/#msg905470 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg905470/#msg905470)) and should see something.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 11, 2016, 08:54:02 am
When the GPSDO starts it initialises the GPS receiver, you should be able to observe that via the pins.  If you can't see that initialisation sequence then it is getting lost somewhere... I would suspect something has fallen off

You can listen to both pin 3 and 4 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg905470/#msg905470 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg905470/#msg905470)) and should see something.

No parts have fallen off. Stupid mistake and tried to solder a broken wire on the serial connection. Forgot to power it off and I suspect some type of ground issue and a ungrounded soldering iron. There was a Arduino project connected to pin 3 of the GPS receiver and powered from the computer USB port. Saw the Arduino rapidly resetting itself. Wondering if it blew the GPS receiver, although thought they were protected?.

No output from the Furuno, just stays high. I also can't see any input going to pin 4 either on reboot. Oh well, sounds like it's toasted. Suspect strongly the receiver

Anyone have a dead board they want to sell the Furuno receiver off of.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on September 11, 2016, 10:50:41 am
Anyone have a dead board they want to sell the Furuno receiver off of.

If you don't see any initialization sent to the receiver even when you took it off the board I strongly suspect you have bigger problems.
Having said that, if you are sure it is the receiver I can send you one.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 12, 2016, 07:24:39 am
If you don't see any initialization sent to the receiver even when you took it off the board I strongly suspect you have bigger problems.
Having said that, if you are sure it is the receiver I can send you one.

I will have another look at pin 4 and see if there is anything there, I just had a quick look on the scope, after not seeing anything on pin 3 just figured it was toast, but yes the main board could have issues as well, although only the one hardware error reported. Thanks for the offer of the receiver, will contact you via PM. Thanks
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on September 12, 2016, 07:29:57 am
I have not looked at what/when the main board sends stuff to the receiver.  It may only send a few commands when you power up.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on September 12, 2016, 09:49:18 am
If you look at... https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg896223/#msg896223 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg896223/#msg896223)

You will see the kind of messages sent at start-up

The $PFEC,GPint,... commands are setting the interval the GPSDO wants to see various messages

I seem to remember that the output of the MCU on the GPSDO board is directly wired (presumably a UART) to the GPS receiver so if you are seeing nothing at the MCU then it is well broken.  You could test continuity from the GPS receiver to MCU pins... can't remember exactly and I don't have my notes to hand.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 12, 2016, 10:15:36 am
If you look at... https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg896223/#msg896223 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg896223/#msg896223)

You will see the kind of messages sent at start-up

The $PFEC,GPint,... commands are setting the interval the GPSDO wants to see various messages

I seem to remember that the output of the MCU on the GPSDO board is directly wired (presumably a UART) to the GPS receiver so if you are seeing nothing at the MCU then it is well broken.  You could test continuity from the GPS receiver to MCU pins... can't remember exactly and I don't have my notes to hand.

Thanks for that, very helpful , will have a look tomorrow. These multi layered boards don't make I easy to back trace. Just received my new Siglent scope with the serial decode feature, so sure that will  assist me. <g>
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 12, 2016, 07:57:55 pm
I seem to remember that the output of the MCU on the GPSDO board is directly wired (presumably a UART) to the GPS receiver so if you are seeing nothing at the MCU then it is well broken.  You could test continuity from the GPS receiver to MCU pins... can't remember exactly and I don't have my notes to hand.

I am wondering if the reason I am not seeing anything on the RX pin is the MCU needs to see some activity from the TX pin before it sends anything to the RX on the Furuno.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on September 12, 2016, 08:17:52 pm
I am wondering if the reason I am not seeing anything on the RX pin is the MCU needs to see some activity from the TX pin before it sends anything to the RX on the Furuno.

I was wondering the same, but I didn't want to lift a receiver from a working board. However, I should be able to monitor both TX and RX pins and see what goes first. And maybe just disconnecting the TX pin and see if there is still commands sent to the receiver. I can do some experiments tomorrow.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on September 12, 2016, 11:17:23 pm
TBH I would expect the GPSDO to talk to the GPS first.

On the Renesas MCU it appears pins 8,9,10 and 11 are UARTs.... thats numbered anti-clockwise from 1 from the cut-off corner...

Might be fun to look there too.

Oh... and I only mentioned bits falling off because it seems bits often fall off in U26, C119 territory.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 13, 2016, 02:07:28 am
Oh... and I only mentioned bits falling off because it seems bits often fall off in U26, C119 territory.

Second time you have mentioned this and I really should have taken your advice the first time |O |O. Went over that area with a loupe and voila what do I see...... a cap that ripped off. >:( I am not sure if that happened when I moved the board around to solder off the receiver or it happened during the original soldering that I though fried the unit. Anyone have an idee what the value would be. Hopefully this was the only issue. Keep my fingers crossed

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 13, 2016, 07:13:04 am
Popped off the cap below C33 as it appears the same 100nf tested, replaced both , but no luck. The cap was probably broken a long time ago.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on September 13, 2016, 07:19:14 am
If you have nothing being sent to the GPS receiver and nothing has fallen off then I would speculate that you have overloaded the output of the MCU and your board is effectively toast.

You could save up some extra $ and buy one of these... eBay auction: #182145209432, looks quite fun.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on September 13, 2016, 06:33:30 pm
I had a look at what the receiver does at startup and it just starts spitting out information about 2 seconds after powering the board.
Yellow trace = RxD, Green trace is TxD. Both go high after power up, and then it starts to send info although it does not get a command in the first 5 seconds.
Bryan, I hope you realized that it is TTL level, not RS232 level? I think if you already removed the receiver you could just apply 3.3V and it should start doing it's thing.

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=255361;image)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 13, 2016, 07:20:50 pm
Thank you very much, I have observed the same in terms of observing both go high but on my board that's it, nothing after that, Yes at TTL, so this has gotten me thinking it's most likely the receiver. Interesting that the receiver starts to transmit and the there is some data received from the MCU. So is the MCU not sending because it doesn't see any data from the receiver or perhaps more going on. The million dollar question ;)

Could be issues with the MCU as well, but I would have thought it would display other messages as well or not respond at all to any serial commands.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 13, 2016, 07:26:56 pm
You could save up some extra $ and buy one of these... eBay auction: #182145209432, looks quite fun.

Think if I can't get this thing going again will use the OCXO and a Jupiter-T receiver I have and  and try this http://www.jrmiller.demon.co.uk/projects/ministd/frqstd0.htm  (http://www.jrmiller.demon.co.uk/projects/ministd/frqstd0.htm)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 13, 2016, 07:33:35 pm
On the Renesas MCU it appears pins 8,9,10 and 11 are UARTs.... thats numbered anti-clockwise from 1 from the cut-off corner...
I don't see a chip named Renesas?. Assume the MCU you are referring to is the Spartan ie  U18
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on September 13, 2016, 09:18:18 pm
U20 = Renasas H8S/2317
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 15, 2016, 05:55:22 am
I had a look at what the receiver does at startup and it just starts spitting out information about 2 seconds after powering the board.
Yellow trace = RxD, Green trace is TxD. Both go high after power up, and then it starts to send info although it does not get a command in the first 5 seconds.
Bryan, I hope you realized that it is TTL level, not RS232 level? I think if you already removed the receiver you could just apply 3.3V and it should start doing it's thing.

I am pretty sure it is the receiver. I unsoldered the receiver off the board again and applied the power lines and the reset line, still no data coming from the receiver. Same as your findings, after two or so seconds the rx and tx lines go high to 3v. But mine does not output any data. I would be surprised if the receiver needed any commands from the MCU before it started communicating, but who knows. Was hoping to see the MCU sending out some data, but maybe it's waiting for some transmission data first. Your scope test seems to show the MCU sends data after the receiver transmits.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on September 15, 2016, 10:47:17 am
Bryan,

The green line is the output from the receiver, it starts without getting any commands from the MCU (yellow line).
Tonight I will remove the receiver from one of my donor boards and power it up. If it starts transmitting it's yours  ;)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 15, 2016, 06:03:38 pm
Bryan,

The green line is the output from the receiver, it starts without getting any commands from the MCU (yellow line).
Tonight I will remove the receiver from one of my donor boards and power it up. If it starts transmitting it's yours  ;)

Thanks very much, will contact you by PM. Fingers crossed that the MCU requires output from the Furuno before it sends commands. If not well then it's game over. The C33 that was broken didn't seem to make  a change, I note there appears to be space for a unpopulated IC on the reverse side and I suspect the cap was just some supporting components that is not needed for the operation of the GPSDO, maybe for another revision or model number?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on September 15, 2016, 07:03:21 pm
Well, this turns out to be interesting - in a bad way.

I removed the receiver and powered it up. It looks like you also have to power the backup voltage and that you have to apply a reset -after- applying the power.
Even then all output I get is what seems to be the software version... in 38400 Baud! No matter how long I wait nothing else is happening.

So either:

 - it needs to be initialized, but my scope shows nothing when looking at the power up of a working pcb.
 - It's broken, but I find that unlikely.
 - I forgot a pin, but I measured a working one and the only difference is that I didn't apply the antenna voltage, again unlikely.
 - Something else I can't think of, likely because it's over 30oC in my lab and after tinkering for an hour I ran away.

It's almost like it is in some kind of test mode, but even then why 38K4 when it normally does 9K6? and the test & flash pins are low as it is in the normal mode.
So for the moment I'm out of ideas, I can't find anything about initializing this thing and it's too warm anyway. I need to think this over and have another go tomorrow.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 15, 2016, 07:13:16 pm
Well, this turns out to be interesting - in a bad way.

I removed the receiver and powered it up. It looks like you also have to power the backup voltage and that you have to apply a reset -after- applying the power.
Even then all output I get is what seems to be the software version... in 38400 Baud! No matter how long I wait nothing else is happening.

So either:

 - it needs to be initialized, but my scope shows nothing when looking at the power up of a working pcb.
 - It's broken, but I find that unlikely.
 - I forgot a pin, but I measured a working one and the only difference is that I didn't apply the antenna voltage, again unlikely.
 - Something else I can't think of, likely because it's over 30oC in my lab and after tinkering for an hour I ran away.

It's almost like it is in some kind of test mode, but even then why 38K4 when it normally does 9K6? and the test & flash pins are low as it is in the normal mode.
So for the moment I'm out of ideas, I can't find anything about initializing this thing and it's too warm anyway. I need to think this over and have another go tomorrow.

Hmm that's interesting and yes in a  bad way as if it requires some type of initialization then likely my board is bad and not the receiver. I have a manual for the Furuno at home and will look it up. I believe pin 7? the Reset needs to be HIGH, but if I recall there is some timing that may be required, seem to recall from memory, something like 1ms. I just assumed the receiver would more or less "freewheel" when it starts and send out NMEA statments.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on September 15, 2016, 10:11:32 pm
You may have multiple issues but if you take a divide and conquer approach....

According to...

http://www.ko4bb.com/manuals/80.229.235.197/Furuno_GT8031_Protocol_Specification_Rev1.pdf (http://www.ko4bb.com/manuals/80.229.235.197/Furuno_GT8031_Protocol_Specification_Rev1.pdf)

the defaults are such that if you get the receiver powered and in satellite site it should eventually send out some info.


Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: uncle_bob on September 15, 2016, 10:15:07 pm
You may have multiple issues but if you take a divide and conquer approach....

According to...

http://www.ko4bb.com/manuals/80.229.235.197/Furuno_GT8031_Protocol_Specification_Rev1.pdf (http://www.ko4bb.com/manuals/80.229.235.197/Furuno_GT8031_Protocol_Specification_Rev1.pdf)

the defaults are such that if you get the receiver powered and in satellite site it should eventually send out some info.

Hi

There are a very small number of GPS module designs that "boot dead" and then need to be initialized. The problem is that vendors are quite happy to supply modules with non-standard firmware. If you are buying enough parts, the module can do almost anything. If the original design was for a unit that did indeed "boot dead", you can get your new module to do the same.

Bob
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 15, 2016, 10:44:29 pm
Quote
Hi

There are a very small number of GPS module designs that "boot dead" and then need to be initialized. The problem is that vendors are quite happy to supply modules with non-standard firmware. If you are buying enough parts, the module can do almost anything. If the original design was for a unit that did indeed "boot dead", you can get your new module to do the same.

Bob

Yes, I was wondering about some type of custom firmware for the Furuno, which in my case probably means the issue could be the MCU as it is not initializing the receiver, but PA0PBZ  tests show nothing is sent from the MCU to the receiver until after the receiver responds.

PA0PBZ , could it be that during your off board test you had the reset held low when it should be high as per the manual?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on September 16, 2016, 07:10:22 am
PA0PBZ , could it be that during your off board test you had the reset held low when it should be high as per the manual?

No, I made the reset go high after applying power to the receiver, I found that when the reset is held high during power up nothing happens al all. Maybe the reset needs to go high within a certain time after power up but according to the timing diagram it doesn't matter. I will hook up a LA to a working board this evening, find out what the timing is and try to reproduce that.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on September 16, 2016, 04:34:53 pm
OK... this is completely over the top but this is the dialog I see between the Renesas and the Furuno...

I have swapped $ for % to indicate a message from Furuno to Renesas...

Code: [Select]
%GPGGA,000002,3444.0000,N,13521.0000,E,0,00,00.00,000000.0,M,0036.7,M,,
%GPZDA,000002,01,01,2002,+00,00
%GPGSV,1,1,00
%GPVTG,,T,,M,,N,,K,N
%PFEC,GPtps,020101000002,1,0,1,000000000000,00,00,000000000000,1147,172802
%GPGGA,000003,3444.0000,N,13521.0000,E,0,00,00.00,000000.0,M,0036.7,M,,
%GPZDA,000003,01,01,2002,+00,00
%GPGSV,1,1,00
%GPVTG,,T,,M,,N,,K,N
%PFEC,GPtps,020101000003,1,0,1,000000000000,00,00,000000000000,1147,172803
%GPGGA,000004,3444.0000,N,13521.0000,E,0,00,00.00,000000.0,M,0036.7,M,,
%GPZDA,000004,01,01,2002,+00,00
%GPGSV,1,1,00
%GPVTG,,T,,M,,N,,K,N
%PFEC,GPtps,020101000004,1,0,1,000000000000,00,00,000000000000,1147,172804
%GPGGA,000005,3444.0000,N,13521.0000,E,0,00,00.00,000000.0,M,0036.7,M,,
%GPZDA,000005,01,01,2002,+00,00
%GPGSV,1,1,00
%GPVTG,,T,,M,,N,,K,N
%PFEC,GPtps,020101000005,1,0,1,000000000000,00,00,000000000000,1147,172805
$PFEC,GPint,GSV00
%GPGGA,000006,3444.0000,N,13521.0000,E,0,00,00.00,000000.0,M,0036.7,M,,
%GPZDA,000006,01,01,2002,+00,00
$PFEC,GPint,VT|%GPGSV,1,1,00
%GVTG,,T,,M,,N,,K,N
%PFEC,GPtps,020101000006,1,0,1,000000000000,00,00,000000000000,1147,172806
$PFEC,GPint,GSV00
%GPGGA,000007,3444.0000,N,13521.0000,E,0,00,00.00,000000.0,M,0036.7,M,,
%GPZDA,000007,01,01,2002,+00,00
%GPGSV,1,1,00
%GPVTG,,T,,M,,N,,K,N
%PFEC,GPtps,020101000007,1,0,1,000000000000,00,00,000000000000,1147,172807
$PFEC,GPint,GSV00
%GPGGA,000008,3444.0000,N,13521.0000,E,0,00,00.00,000000.0,M,0036.7,M,,
%GPZDA,000008,01,01,2002,+00,00
$PFEC,GPint,ZD|%GPGSV,1,1,00
%GVTG,,T,,M,,N,,K,N
%PFEC,GPtps,020101000008,1,0,1,000000000000,00,00,000000000000,1147,172808
$PFEC,GPint,GSV00

So at startup the Furuno sends quite a few messages, unsolicited. Then it gets a series of commands from the Renesas and then after a while things start generally interleaving and getting more confusing!


If you look at Section 1.5 in the receiver software spec you will see values like... "N34deg.44.0000 min. E135deg.21.0000 min." as default values following restart without battery back-up, so

%GPGGA,000002,3444.0000,N,13521.0000,E,0,00,00.00,000000.0,M,0036.7,M,,

isn't that unexpected and confirms the the Furuno sends first.

Share and Enjoy

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on September 16, 2016, 06:58:04 pm
isn't that unexpected and confirms the the Furuno sends first.

Yes, I fully agree and I can see the same on a working unit, it's just that I can't get the receiver running on its own.
I grabbed the signals from the working unit and this is the result:

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=256293;image)

Also as expected, reset goes high about 200 ms after power up. (TEST and MODE both stay low)
So I hooked up the spare receiver in parallel, that is to say GND, VCC, VBCK and RST_N (and later also RD and VANT when it first didn't work), but it keeps doing what it does: spitting out the firmware version in 38K4. The only logical explanation I have is that it's broken, but how that happened I have no idea. I have 2 more donor boards so I can take off another receiver but it's a bit of a fight and I didn't feel like it this evening. If anyone has a suggestion other than a broken receiver I'd love to hear it.  :-//

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on September 16, 2016, 09:18:23 pm
RST_N should presumeably be wired HI when operating stand-alone?


Is it sending $PFEC,GPtrq ?  That suggests it is in Self-Test mode
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 17, 2016, 01:57:54 am
Thanks everyone for taking the time to test out their boards, for me it looks like it's the Furuno for sure with the possibility of the MCU as collateral damage. I suspect the Furuno is receiving some type of initialization from the MCU after it "handshakes" in some fashion. This would probably explain while you can't send anything from the RXD pin or was it very limited commands that the Furuno would respond to?. If it was  fully "unlocked" it should accept all the commands in the operating guide and send back the corresponding NMEA response. Or maybe a custom firmware on the Furuno from the get go.

Can anyone confirm which pins the on the Renasas is sending and receiving data for the Furuno. Is it 8,9,10 and 11
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on September 21, 2016, 05:56:46 pm
Victory at last!  :phew:

Took another receiver from another donor board, 3.3V to pins 7 and 9, GND to pin 8, pin 6 with 4k7 to 3.3V and grounded. Applied power, removed the ground to pin 6 and the thing starts its once per second report. So it looks like I had a bad receiver the first time after all.  :--

Bryan, if you try the same and you don't get any output your receiver is probably bad.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 22, 2016, 01:58:06 am
Thanks for taking the time to test. I will try the same this weekend and report back.

p.s. With the receiver off the board are you seeing any activity on the MCU/ main board. Is the MCU transmitting anything or is it silent so to speak.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on September 22, 2016, 07:09:23 am
I did not take the receiver from a working main board, so I can't test that.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on September 25, 2016, 09:21:01 am
I did not take the receiver from a working main board, so I can't test that.

Well, hooked up the receiver off board the same as you did, it's dead. No output at all :-[
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on October 03, 2016, 09:09:31 am
Does anyone happen to have a datasheet or specs for the OCXO. All I can find is that it is likely made by C-MAC at one time and rebadged.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Jacobo on November 01, 2016, 11:36:12 pm
Having a problem with Trimble 57964. GPS works fine, module can see 7 to 9 satellites. However it never enables output. Initially it looks like this
Code: [Select]
UCCM >stat

               - UCCM Slot STATE-

1-1. #Now ACTIVE STATUS ---------------- [Alarm]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warm]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [GPS]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL [ LINK ]
     #OPERATION ALARM ------------------ [LINK ]
3-1. #PLL STATUS ----------------------- [ENABLE]
3-2. #Current PLL MODE ----------------- [ENABLE][/font]

but after a while switches to external reference
Code: [Select]
UCCM >stat

               - UCCM Slot STATE-

1-1. #Now ACTIVE STATUS ---------------- [Alarm]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warm]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [NONE]
2-3. #Current Select Reference --------- [X1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL [ LINK ]
     #OPERATION ALARM ------------------ [LINK ]
3-1. #PLL STATUS ----------------------- [ENABLE]
3-2. #Current PLL MODE ----------------- [ENABLE]

Logs are as follows
Code: [Select]
UCCM >diag:log:read:all?

Log status:   8 entries

L00:16/11/01.23:24:23 Log cleared
L01:99/08/22.00:00:01 Output mode: Alarm
L02:99/08/22.00:00:01 Power up start
L03:99/08/22.00:00:01 A/S change: Slave(HIGH)
L04:99/08/22.00:00:01 REF_SEL change: LINK(HIGH)
L05:16/11/01.23:27:12 Ref available
L06:16/11/01.23:28:27 Ref Change: GPS
L07:16/11/01.23:28:28 Ref chang: External PPS

and SYSTem:STATe? output are
Code: [Select]
UCCM >syst:stat?

-------------------------------------------------------------------------------
57964-05     serial number  86927905     firmware ver  1.0.0.2-01 W-CDMA  mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
XX Ref 8KHz 0: [LOS]
XX Ref 8KHz 1: [LOS]                          TFOM     9            FFOM      1
XX Ref 8KHz 2: [LOS]                          UCCM A Status[ALARM]
XX Ref 8KHz 3: [LOS]
>> GPS: [phase:+1.3E+01, settling]
ACQUISITION ...................................................[GPS 1PPS Valid]
Tracking: 8 ____   Not Tracking: 4 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      23:31:27     01 Nov 2016
 22   3  13   41    17  -- ---
  7  53 243   41    15  -- ---                ANT DLY  0 ns
  9  74 193   41    31  -- ---                Position ________________________
 23  59  71   46    19  -- ---                MODE     Hold
  8  21  48   44
 27  24  91   43                              LAT      S  34:YY:XX.607
  3  17   3   43                              LON      E 150:ZZ:WW.968
 30  26 270   36                              HGT               +76.55 m (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------

Regards, hope I'm just missing some command, as I bought this module a while ago and been waiting for GPS antenna to test it, so return period is over on this purchase...

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ZigmundRat on November 02, 2016, 09:11:51 pm
Have you tried:

SYNC:REF:DISABLE LINK
SYNC:REF:ENABLE GPS
REF:TYPE GPS
OUTP:TP:SEL PP1S

This should force the ref to GPS (and the output to 1PPS).
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on November 02, 2016, 09:21:26 pm
On the ACTIVE STATUS the GPS is presenting an ALARM.

Run the hardware alarm? and operation alarm? to see where te error came from.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Jacobo on November 02, 2016, 11:22:39 pm
Hi ZigmundRat,

Have you tried:

SYNC:REF:DISABLE LINK
SYNC:REF:ENABLE GPS
REF:TYPE GPS
OUTP:TP:SEL PP1S

This should force the ref to GPS (and the output to 1PPS).
Good point, I was wandering myself. I have tried those commands, all worked except REF:TYPE GPS. which complains - Parameter error

Hi Nuno_pt,
On the ACTIVE STATUS the GPS is presenting an ALARM.

Run the hardware alarm? and operation alarm? to see where te error came from.
No alarms, both operation and hardware alarms return NONE.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Nuno_pt on November 02, 2016, 11:23:52 pm
Do you've the GPS antenna connected?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Jacobo on November 02, 2016, 11:47:29 pm
Do you've the GPS antenna connected?
Yep. 7 to 9 satellites are visible at any given time.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Jacobo on November 02, 2016, 11:58:46 pm
I suspect the OCXO is a culprit. I have connected frequency counter to OCXO output directly and tried to change VFB pin voltage - no frequency shift at all. The issue is that I'm not 100% sure in my frequency counter, this GPSDO was purchased to calibrate it;) Still I think short term stability is enough to check OCXO...

Anyone knows what frequency swing I should expect from Trimble 65256 OCXO?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on November 03, 2016, 01:47:11 am
Confused, you say no output, but yet say there is output from the OCXO. Do you mean there is no output on the SMA/B connector for 10Mhz but output from the OCXO itself ?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Jacobo on November 03, 2016, 01:52:49 am
Confused, you say no output, but yet say there is output from the OCXO. Do you mean there is no output on the SMA/B connector for 10Mhz but output from the OCXO itself ?

Sorry for confusion. that's correct, no output from SMB connector of GPSDO, I'm checking directly on OCXO pin. After more close look it seems that swing from 0 V to 4 V produces frequency change about +-4Hz. I think it must be an order of magnitude bigger +-40Hz or something.

So I'm still suspect OCXO not able to adjust frequency and PLL can't lock a loop, so it switch to external ref.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on November 05, 2016, 08:41:15 am
Hmm, so you suspect that the OCXO is defective as it can not be adjusted by the PLL and the MCU is kicking the 10Mhz output off. I suppose that is a possibility. I assume you have done the factory reset. What is the voltage on the OCXO REF pin. I would also carefully look over the board with a magnifying glass and look for any ripped off SMD components. I think it's, more likely there is a missing or defective component that is causing the loss of the 10Mhz output to the connector i.e. the output to the buffer, amplifier etc.. I would even try back tracing a bit on the SMA/B connector and see if that leads anywhere.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Jacobo on November 05, 2016, 09:58:07 am
Hi Bryan,

Thanks for your advise. You are right, I did perform factory reset - it didn't help. actually I have some suspicions, but I didn't want to touch board until I'm negotiating a return... but just now I got response from eBay seller - this scum want's me to return it back, so he can sell it again! and he was brave enough to write it in eBay message! So I might have no other choice but try to fix it myself... and escalate to eBay for a full refund..

Soo.... back to business... vref is 2.7V from memory. Fvb pin swap from 1V to 4V on startup and then stays at 2.7V all the time. Though I can't see much frequency change on OCXO output during startup... +- few Hertz is all I can see. Which is most likely is not enough to lock the loop.

Also after some hours with DMM I found that D13 is short, supposed to be a 2.8V Zener diode according to marks on it. (I have Trimble 57963-B).

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on November 05, 2016, 08:11:03 pm
If I recall the control range is 0-5v, so I would suspect that if you are sitting at  2.7v you are fine. If the PLL could not lock would it not be trying to adjust the voltage downward or upwards to the extreme ends of the control range. Hopefully the shorted zener is the issue. Earlier in the thread there is a couple high resolution photos of the board. I would carefully compare looking for a missing SMD component. The boards are really handled rough.

What equipment are you testing the OCXO frequency with?. Strange that the OCXO frequency is only varying slightly upon warm up, unless these are very good OCXO's !!  Would be so great if there was a schematic or flow diagram for these.

Pretty much standard for the response you received from the seller. Which seller was it.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Jacobo on November 06, 2016, 12:13:58 pm
Hi Bryan,

that's what I observe - Fvb pin jump from 0.5V to 4.4V during module init, and if I check at that moment it will say that ref is GPS, then module switch to external ref and Vfb back to 2.4V.

And during that 0.5V to 4.4V swing I can see only 10 Hz change on OCXO output pin. obviously that's not enough, so OCXO still my suspect.

As for shorten zenner - I have unsoldered it and pads where zenner supposed to be still short, while zenner itself looks ok. so short must be somewhere else. but I can't find the trace, as it short to the ground... There are too many pins:(

PS: I don't want to name seller as of yet.. But his name been mentioned in t his thread several times;)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: PA0PBZ on November 06, 2016, 12:55:24 pm
Also after some hours with DMM I found that D13 is short, supposed to be a 2.8V Zener diode according to marks on it. (I have Trimble 57963-B).

Where is this D13? I can't find it on the pcb.
Is your L20 damaged? It is a weak point and used to couple the 10 MHz signal from the OCXO.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on November 06, 2016, 09:01:40 pm
Hi Bryan,

that's what I observe - Fvb pin jump from 0.5V to 4.4V during module init, and if I check at that moment it will say that ref is GPS, then module switch to external ref and Vfb back to 2.4V.

And during that 0.5V to 4.4V swing I can see only 10 Hz change on OCXO output pin. obviously that's not enough, so OCXO still my suspect.

Hmm, that does sound suspect. Perhaps another member could test their working board. Mine is broken so can't test. OCXO can vary quite a lot in the control range and some are fairly narrow so having a 10Hz change may be completely normal. My money is a component missing/broken or defective on the board. If you have a good accurate frequency monitor you could easily yank the OCXO off the board power it up and test it with a variable power supply on the control pin to see what it takes to get to 10MHz. That should eliminate the OCXO and put the blame on the PLL or feedback circuitry.

Another thing to look for is the circuitry around the Mact switch. This switch can put the board in a state where it's outputs a rough 10MHZ if a antenna disconnect is going to occur., what I never got around to testing is does it just set the Vfb pin to 2.5v as a ballpark or so or does it keep the last vfb voltage and hold it their until the unit goes out of holdover. But I think it notifies the user via the RS232 port if activated.

Ok, I think I know which seller. I often wonder why as a seller they advertise as working and then be faced with refunding money for the defective ones. I suppose it's because if you advertised them as for parts only nobody would buy at the going rate. Probably more economical all around to refund the buyers that complain loud enough. Another topic I suppose.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Jacobo on November 07, 2016, 11:02:55 pm
PA0PBZ, I can't see any damaged or missing components on the board. D13 is under GPS receiver. After more detailed observation I think that's by design. So at that moment I don't think this is an issue.

Bryan, I can't believe that OCXO have 1ppm regulation, I think crystal aging would be around 5ppm... so regulation must be much wide, so I have ordered a new OCXO and waiting it to arrive.
As for MACT switch - as far as I can say it just enable output, while board still trying to do it's things - like locking OCXO to GPS or whatever reference is. So MACT doesn't impact Vfb at all, to my best understanding.

Another question is how PLL works - I can observe 9.765606kHz signal in PLL UP/DOWN outputs, meaning that this is frequency phase detector is working on. It's 10MHz / 1024, so it's obvious how to get it from OCXO frequency. However, I can't understand how they obtain reference frequency from GPS, as far as I understand there is nothing with such a frequency that comes from GPS sygnal... Anyway it comes from FPGA, so I can't really tell how PLL works, so I assuming it works.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: enaxy on November 10, 2016, 02:01:32 pm
Hi.
I am from Slovakia. Trimble 57964-15 GPSDO bought from eBay . It works fine.
 Connection via HyperTerminal COM1 is right. But when I run LADY HEATHER or TBOLTMON I do not see anything.

 COM communication I have configured your 9600 8N1 and thus also communicate via Telnet / HyperTerminal.

 Where can I have a problem that Lady Heather and TBOLTMON shows nothing? Thank you.

UCCM Slot STATE-

1-1. #Now ACTIVE STATUS ---------------- [Master]
1-2. #Before ACTIVE STATUS ------------- [OCXO Warm]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [GPS]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL [ LINK ]
     #OPERATION ALARM ------------------ [LINK ]
3-1. #PLL STATUS ----------------------- [ENABLE]
3-2. #Current PLL MODE ----------------- [NORMAL 2 MODE]
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: deepskyridge on November 10, 2016, 02:28:34 pm
TBOLTMON and Lady Heather both use TSIP for comms, the UCCM does not use TSIP.

There was some work on Lady Heather to support the UCCM but I have not seen anything recently.

Gary
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on November 10, 2016, 06:08:43 pm

 Where can I have a problem that Lady Heather and TBOLTMON shows nothing? Thank you.


The version of Lady Heather that works with these "UCCM" receivers should be out in a couple of weeks (really!).  I've been writing some MUCH better documentation for it.  It's up to 3000 lines long now, and I have another 300 or so more to do.

I also just added support for talking to the management interface of the Oscilloquartz Star-4 receivers.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: enaxy on November 10, 2016, 10:28:48 pm
Thank you so much for your work. I'm excited. It's like a gift for Christmas
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Confucian on November 24, 2016, 03:21:45 pm
I got my simple 1 in 4 out 10MHz distribution working. The RF transformers are probably overkill but I found them at eBay auction: #251401324712 and could not resist.
Schematic attached and bare PCB at cost if anyone else is interested.

Finally got my distribution amps sorted, Thanks NivagSwerdna for the PCB's and the relevant info. Dont like MCX connectors so went SMA, I used single sided pcb and Lidl's Sardine tins to make screened enclosures.
 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: guido on December 12, 2016, 11:49:16 pm
Contact made  :)

My UCCM unit is now talking to Lady Heather! I'm using an acient win98 PC with a real RS232 port and a max232 chip inbetween PC and UCCM.
Still need to finish the whole project someday...

http://www.ke5fx.com/heather/readme.htm (http://www.ke5fx.com/heather/readme.htm)

A big thanks to Mark, John and others for the program  :clap: :clap: :clap:
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: enaxy on December 14, 2016, 07:10:58 am
THANKE soooooo muuuuuuch   :-+
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on December 19, 2016, 03:51:59 am
Thanks so much for getting Lady Heather working with these units. This has to be one of the coolest apps ever! I'd rather stare at this than looking at supermodels.  It appears that the TCP server available only runs on Windows via a batch script. I found a way to use a Linux based TCP <> serial server that connects to a Lady Heather client. My intention is to embed a Raspberry Pi (Which also runs this new version of Lady Heather) into the box with the receiver and then run a client on a different machine. I downloaded "ser2net" from https://sourceforge.net/projects/ser2net/
Then I built it, installed it, then added a single line to it's config file: /etc/ser2net.conf
45000:raw:600:/dev/ttyUSB0:57600 NONE 1STOPBIT 8DATABITS XONXOFF LOCAL -RTSCTS
Ensure this port isn't blocked by any firewalls. I connect to it using the -ip=XXX.XXX.XXX.XXX option in the heather.cfg file.

Currently I'm using a USB dongle on a laptop as a server. The dongle doesn't work very will with a Raspberry Pi. There is a lot of latency probably from the way it buffers the data. I plan on using the serial port on the Pi directly attached to the signals before the RS-232 converter on the receiver after disconnecting the data lines from the converter and ensuring that the levels are 3.3v, which is what the Pi is expecting.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on December 19, 2016, 04:02:16 am
Thanks so much for getting Lady Heather working with these units.

Currently I'm using a USB dongle on a laptop as a server. The dongle doesn't work very will with a Raspberry Pi. There is a lot of latency probably from the way it buffers the data. I plan on using the serial port on the Pi directly attached to the signals before the RS-232 converter on the receiver after disconnecting the data lines from the converter and ensuring that the levels are 3.3v, which is what the Pi is expecting.

Think that's cool?  I have added some touchscreen code to Heather and better support for small screens.  It's working very will with a PI + official PI touchscreen.  Here's a photo of a neat Beaglebone version running a 5" touchscreen.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TiN on December 19, 2016, 04:56:40 am
Nuts, I want one now.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on December 19, 2016, 05:22:38 am
Nuts, I want one now.

The touchscreen support should work with any touchscreen that emulates a mouse (or you can also just use a mouse).   Touch the upper left hand corner of the screen, and an on-screen keyboard pops up for entering commands.  Or touch any of the "clickable" items on the screen and that item zooms to a full screen view... it's way cool...

The PI touchscreen display is very nice.   It spurred me to figure out how to get X11 to not put borders and title bars on the window so I can do a full-screen display and not waste precious tiny screen pixels to the X11 window manager window decorations. 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Vgkid on December 19, 2016, 05:23:42 am
@ TXPyro
I haven't been keeping updated with this.
So you are the guy on the Time Nuts group. Nice work  :-+
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on December 19, 2016, 12:57:05 pm
Nuts, I want one now.
That's very fun.  Which screen is that?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on December 19, 2016, 04:24:30 pm
Nuts, I want one now.
That's very fun.  Which screen is that?

I'm not sure... another person built that around a Beaglebone with an LCD cape.   I'm using the official Raspberry PI touchscreen.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on December 20, 2016, 05:37:12 am
The touch screen is pretty cool! I decided that I'm just going to run an instance of Lady Heather on the embedded Raspberry Pi and then connect to it via a VNC client rather than just use the RP as a serial <> TCP server. That way, it can run without interruption and not have to use another computer. The direct serial port connection to the RP works much better than through a USB dongle. If I build another one, I may consider using a touch screen.

On another note, does anyone have a hi res scan of the Trimble version? I have one that works fine except that the status LEDs don't work. I'm wondering if there is a jumper or missing resistor on this one. I didn't see any damaged components. I'm just wondering if this was a "feature".
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on December 20, 2016, 06:32:14 am
The direct serial port connection to the RP works much better than through a USB dongle.

I've had a lot of problems with cheap USB-serial converters on Linux machines.  The main issue that I see is you cannot set the baud rate.  I suspect the clone chips in them are not cloney enough.  All the ones with cloned CH3xx chips seem to have the problem.  The ones with cloned PL23xx chips seem to be OK on Linux, but not on Windows / macOS  with the "official" Prolific drivers... even early versions that supposedly don't check for clones.

Another minor issue with the USB converters on Linux shows up doing the auto-detect of receiver type.  This tries to collect 512 bytes or 3 seconds of data (whichever happens first) at each baud rate it tries.  With some Linux distros it can take longer than three seconds... which cannot happen unless the driver is doing something naughty that effectively stops or slows the system clock.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: LY1 on December 21, 2016, 10:53:19 am
Hello,

I have this: http://www.ebay.com/itm/GPSDO-Symmetricom-Inside-GPS-10MHz-1PPS-GPS-Disciplined-Clock-GPS-Ant-Display-/172166437092?hash=item2815eb58e4:g:Ze8AAOSw1DtXFbR8 (http://www.ebay.com/itm/GPSDO-Symmetricom-Inside-GPS-10MHz-1PPS-GPS-Disciplined-Clock-GPS-Ant-Display-/172166437092?hash=item2815eb58e4:g:Ze8AAOSw1DtXFbR8) 

Inside it has a http://i.imgur.com/Eb1v00q.jpg (http://i.imgur.com/Eb1v00q.jpg)

10Mhz output is working fine. When GPS have LOCK I have an output off 10Mhz.

1PPS output is not working. I do not get 1PPS signal when GPS LOCKs.

How I can get 1PPS signal?
Maybe I need something set via RS-232 and command line?
Or maybe my pcb board is fault?
Thanks for the replies.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on December 21, 2016, 07:30:58 pm
It's a pretty fast pulse. What are you using to "see" it?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: LY1 on December 22, 2016, 06:25:39 am
It's a pretty fast pulse. What are you using to "see" it?

Hello,

I have tektronix 2465b. Enough or not this scope for 1PPS pulse watching?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Macbeth on December 23, 2016, 03:22:30 am
You should easily see the pulse if you trigger for it. It's very narrow in the wider scheme, 20us pulse width IIRC. It should be 1PPS but could be set to PP2S (every 2 seconds).
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Tom45 on December 23, 2016, 03:15:58 pm
The pps pulse width is 50 usec on my unit.

If it is there on your gpsdo you should be able to see it if you set 20 usec/div sweep and trigger on rising edge at a level of a few tenths of a volt.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on December 23, 2016, 04:33:02 pm
It's 50 us on my unit as well. If you are running in "auto trigger" mode, you may not see it on older analog scopes.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: LY1 on December 24, 2016, 07:48:19 am
The pps pulse width is 50 usec on my unit.

If it is there on your gpsdo you should be able to see it if you set 20 usec/div sweep and trigger on rising edge at a level of a few tenths of a volt.

Can you or anybody else add a photo how looks 1pps pulse? I can get it from my unit.

I think my unit is fault. (10Mhz I can see clearly, 78ns rite time impulse too). 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Tom45 on December 24, 2016, 06:15:46 pm
Here is a photo showing the pps signal on my 2465. You should be able to see all of the settings I used. I adjusted the horizontal position over to the right a bit so that the leading edge of the pulse is visible.

This is a 2 second time exposure to show the pulse. In real time, the screen is blank except for the trace as shown that flashes briefly once per second.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: NivagSwerdna on December 26, 2016, 07:25:00 pm
1PPS output is not working. I do not get 1PPS signal when GPS LOCKs.

If you look at https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg934866/#msg934866 (https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg934866/#msg934866) you will see the PPS from both the GPS receiver and the 1PPS from the GPSDO itself.  The GPSDO pulse is around 50us and the GPS is around 500ms; they both occur at the same time when all is locked.

I cant remember exactly but you might not get PPS from the GPSDO until is is fully locked.  What is happening to your status? 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: LY1 on January 01, 2017, 04:26:43 pm
Hello,

Thanks all for helping. Via RS232 I have used this (I think, because I have used a lot off command and I get 1pps working) command: REFerence:TYPE GPS|LINK or SYSTem:PRESet
Changed from Link to GPS and I have now 1PPS like in Tom45 post photo.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: enaxy on January 03, 2017, 07:27:03 am
Hi all.

Still wait for FAKRA antenna reduction and make labels to the panel. It will be completed. Thank you for this forum.

The box is from eBay http://www.ebay.com/itm/331071040666?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/331071040666?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

Power supply is the Goobay Eco-Friendly 2250mA Switch adaptor. http://www.ebay.com/sch/sis.html?_nkw=Goobay+EcoFriendly+Universal+Voltage+Power+Supply+2250+Ma+Switchable+3+12+V+New&_itemId=311602598953&_trksid=p2047675.m4099 (http://www.ebay.com/sch/sis.html?_nkw=Goobay+EcoFriendly+Universal+Voltage+Power+Supply+2250+Ma+Switchable+3+12+V+New&_itemId=311602598953&_trksid=p2047675.m4099)     Disassembled and modified resistive divider on the 6V position to 6.2V voltage.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: LY1 on January 03, 2017, 08:49:35 pm
Symmetricom GPSDO 1pps signal
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: digital_dreamer on January 05, 2017, 12:22:33 am
Think that's cool?  I have added some touchscreen code to Heather and better support for small screens.  It's working very will with a PI + official PI touchscreen.  Here's a photo of a neat Beaglebone version running a 5" touchscreen.

Now, that's cool.
Is that the 800x480 screen? Resistive or capacitance TP?

Now that I'm here, I got some issues.  :P

I've have had a Trimble 57964 board for a year now and have used it with OS X, okay macOS Yosemite (10.10.5), and connect via Terminal and a Keyspan (Now Tripplite) USA-19HS RS232 to USB adapter. No problems there.

With the release of support for the UCCM GPSDOs, I tried out Lady Heather on this board in WIN 7, using the same USB adapter. Cool. I used to use LH on other GPSDO boards some time ago. But, given that I stay mostly in macOS, I decided to try the x11 version of LH 5.00 and am not having success connecting. I'm using the precompiled version already in the directory.

I can connect via Terminal: screen /dev/tty.KeySerial1 57600
In Heather, I use -id=/dev/tty.KeySerial1 in the .cfg file or just type ./heather -id=/dev/tty.KeySerial1 (when in the directory).
All I get is a seeming hangup on connecting to the com port:
Code: [Select]
program:heather
chime_file:1
alarm_file:1
leap_file:1
sunrise_file:1
noon_file:1
chord_file:0
noiify_file:2
bell_file:1
read_config_file(name:heather  local:1  add:1)  path:./
Attempting to open config file(./heather.cfg):(./heather.cfg)
Reading config file:./heather.cfg
opening com device:/dev/tty.KeySerial1
read_config_file(name:heather  local:2  add:1)  path:./
Attempting to open config file(./heather.cal):(./heather.cal)
Reading calendar file:./heather.cal

Initializing memory...
Done...

opening com device:/dev/tty.KeySerial1
The LED on the adapter stops flashing, so I know it's identified correctly.

Any debugging I can do here? Believe me, I've tried other ports, but this one is the only one in use. Everything else is /dev/ttyp0 on up.
I might as well mention that I'm not at all familiar with the x11 windowing system in OS X. Yes, I did install XQuartz, but beyond that I know nothing.

best regards and thanks for all your hard work on making this work for our GPSDOs.
MAJ
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 05, 2017, 12:47:40 am
I'm using the "official" PI touchscreen (7", 800x480, capacitive).   The device in the photo is another guy's unit running a 5" screen on a Beaglebone.

In your OSX output data, it is opening the serial port, reading all the files, etc.  The next thing it should show is opening the XQuartz "X11" display.  It seems like something is wrong with your X11 installation.  What version of OSX and XQuartz are you using?   The binary was compiled on El Capitan.  I'm currently using XQuartz 2.7.9.  I'm running it on a 2012 Mac Mini.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 05, 2017, 10:17:12 pm
In your OSX output data, it is opening the serial port, reading all the files, etc.  The next thing it should show is opening the XQuartz "X11" display.  It seems like something is wrong with your X11 installation.

I forgot to mention that you need to logout/login or restart your system after installing XQuartz...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: digital_dreamer on January 06, 2017, 01:51:46 am
In your OSX output data, it is opening the serial port, reading all the files, etc.  The next thing it should show is opening the XQuartz "X11" display.  It seems like something is wrong with your X11 installation.

I forgot to mention that you need to logout/login or restart your system after installing XQuartz...
Awesome! That's all that was needed - a logout and back in.
Never thought I'd be running this in macOS. Great progress.

MAJ

BTW, this is XQuartz 2.7.11 on macOS 10.10.11 (Yosemite) on a Gigabyte GA-EX58-UD5 based hackintosh (Intel Core i7 920 (quad-core) @ 3.4GHz w/Fusion drive and NVIDIA GeForce GTX 680 GPU).

(https://dl.dropboxusercontent.com/u/1180773/Lady_Heather_Screenshot.png)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Tom45 on January 07, 2017, 03:09:08 am
I decided to watch the OCXO control voltage on my GPSDO and saw random relatively wild oscillations on my 34465 trend graph display. So I saved some log files and graphed them.

The first graph is from an 11 hour (40000 points) run. The second graph is a 20000 point run (5.5 hours). Voltage was logged once per second in all runs. The third graph shows a closeup of the spike in the second run.

This is a Symmetricom UCCM P.

Any ideas what might be going on here? Could it be that it sometimes doesn't see enough satellites?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 07, 2017, 03:21:18 am
Any ideas what might be going on here? Could it be that it sometimes doesn't see enough satellites?

You have a horrible sky view to the east...

It could be.  Lady Heather plots the number of used satellites as the CYAN colored graph at the bottom of the plot area.  See if the jumps in the green DAC plot match changes in the sat count plot. 

Thunderbolt receivers show changes in the DAC value whenever the satellites used change.  The DAC changes get smaller the better your surveyed position is.

I have noticed that some of these "UCCM" receivers seem to periodically do some kind of adjustments to their PLL settings.   I seem to remember one does something every 45 minutes or so...
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Tom45 on January 07, 2017, 04:35:05 pm
Actually I don't have any view to the east. The antenna is looking out a west facing window in the north west corner of my house. After getting the gpsdo I put the antenna next to the window just to verify that it worked. It seemed to be OK, at least until I decided to monitor the control voltage.

Following your suggestion I watched the number of satellites and the control voltage. Since my previous monitoring showed that it could be fine for several hours at a time, I didn't know if I would have the patience to sit it out.  But I was lucky enough to have it drop to 2 satellites for a few minutes. And sure enough, the control voltage oscillated. I moved the antenna away from the window and got a similar oscillation.

So I guess it's time to figure out how to run a longer coax outside to get the antenna in a better and permanent location.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 10, 2017, 03:19:44 am
Been running LadyHeather 5.0 for a few days now with my Trimble UCCM receiver. Check out the GPS dead zone to the north of me.

(https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/?action=dlattach;attach=284250;image)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Krytron on January 10, 2017, 05:01:14 am
[quote ...   Check out the GPS dead zone to the north of me.

Your plot missing north is normal for GPS.  Its due to the polar orbits the GPS satellites are in.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 10, 2017, 05:18:30 am
Been running LadyHeather 5.0 for a few days now with my Trimble UCCM receiver. Check out the GPS dead zone to the north of me.

Due to the satellite orbits, the size and shape of those dead zones depends upon your latitude.   In the southern hemisphere, the dead zones swap to the bottom of the map.

Here's what one looks like in New Zealand:
http://www.febo.com/pipermail/time-nuts/attachments/20161221/f152ac9c/attachment.gif (http://www.febo.com/pipermail/time-nuts/attachments/20161221/f152ac9c/attachment.gif)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 10, 2017, 05:52:53 am
Yeah, just thought it was pretty cool how nicely LH mapped it out. You can even make out where trees are and see a slightly weaker signal in close because of the antenna tower on the east side of the antenna. I have now switched to the antenna on the opposite side of the tower and should see the weaker signal to the west.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 10, 2017, 06:02:25 am
Yeah, just thought it was pretty cool how nicely LH mapped it out. You can even make out where trees are and see a slightly weaker signal in close because of the antenna tower on the east side of the antenna. I have now switched to the antenna on the opposite side of the tower and should see the weaker signal to the west.

Try the ZU command (I think that's in V5.0) to see some other versions of the signal level maps...  from the ZU display you can click on the various maps to bring them full screen.  If ZU doesn't work try ZA, ZR, and ZE.

In V5.0 the signal level maps are based on the average signal levels seen at a given sky position since the program was started.  I've since changed that to restart the averaging (from the current average values) every 24 hours.  That way if something happens to your antenna setup,  the change in signal levels won't be swamped out by the old accumulated data.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 10, 2017, 06:07:11 am
The updates you've made are amazing. Shame my ancient HP 58501A doesn't support any commands (that I can find) to use it with LH.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 10, 2017, 06:50:05 am
The updates you've made are amazing. Shame my ancient HP 58501A doesn't support any commands (that I can find) to use it with LH.

Heather does work with the HP5xxxx/Z3816A/Z3817A devices (use the /rx5 command line option),  but with V5.0 you have to first manually configure them to turn off "full duplex" mode that echoes the serial input data.  Heather does send a command to turn off full duplex mode, but it does not work with all devices/firmwares.  The next rev sends the proper command that should work with everything.  But it sounds like your unit is so old it does not support HP's standard GPSDO command set.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 10, 2017, 07:20:08 am
I can see the commands in ASCII in the firmware I've dumped from it but none of them respond. It's a one off very early unit.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 10, 2017, 06:06:54 pm
Yeah, just thought it was pretty cool how nicely LH mapped it out. You can even make out where trees are and see a slightly weaker signal in close because of the antenna tower on the east side of the antenna. I have now switched to the antenna on the opposite side of the tower and should see the weaker signal to the west.

If possible, put the antenna on the south side of the tower.  That way, the tower isn't blocking any satellites.

Here's my antenna pattern.  I live on the top floor, south side of an apartment building.  The antenna is bolted to my balcony railing.  Nothing but sky to the east, west, and south.  Even so, this pattern took a couple of months to build up.  There were pie-shaped cutouts that were simply due to the fact that there were no satellites there.  Over time, the satellites drifted around and filled up the cutouts.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 10, 2017, 06:48:33 pm
[ Even so, this pattern took a couple of months to build up.  There were pie-shaped cutouts that were simply due to the fact that there were no satellites there.  Over time, the satellites drifted around and filled up the cutouts.

That's a VERY nice antenna pattern.  You must have an exceptional sky view... mine sucks... ground level antenna,  lots of tress and obsctructions,  two story house.

The sats typically cross the sky in 6 hours and the orbits repeat every 12 hours.

Depending upon how many sats your receiver can track,  you should get a pretty much full antenna pattern within 12-24 hours.   There may be a couple of minor arcs of blackness (usually north-south) and some scallops around the edges where no sats have been.  My multi-GNSS receivers that typically track 20+ satellites fill in everything within a few hours. 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 11, 2017, 04:54:43 am
And 24 hours later this is the image with my more eastern antenna - more or less the same as expected.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 11, 2017, 06:18:20 am
And 24 hours later this is the image with my more eastern antenna - more or less the same as expected.

You might want to check your elevation mask.  Use the S - A - E commands to see the elevation angle where the signal level drops and set the elevation mask accordingly.  In my case, a value of 15 degrees is appropriate.  AFAIK, the signals near the horizon should be excluded due to high noise levels and/or multipath which could degrade the short-term performance.  The yellow tips on your graph suggests that the mask might need to be raised a bit.


Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 11, 2017, 06:35:32 am
You are very correct - it is currently 5 degrees, 15 would be much more appropriate.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: K1FPV on January 12, 2017, 11:22:31 pm
Hi All,
I purchased one of these GPSDO's close to a year ago. At the tie I bought it, I tried it out and it worked fine. A week or so later, I acquired a Spectracom Ageless Master Oscillator and have used that to this point to supply reference for my counter and other equipment.

This week, I decided to hook it up again and it is non-functioning. I push the RST button (I assume it is a reset button) and it merely reboots like it used to do only no 10 MHz out or 1 PPS. I hit the other reset button labeled MACI and the 2 upper green LEDs flash back and forth. In either case, I get no 10 MHZ or 1 pps.

Has anyone else encountered this? I looked back a number of pages on this thread, but saw no mention of this unless I accidentally overlooked it. It is too late to ask the seller to make good on it. I should have ran it more than a few minutes when I initially bought it.

Bill
K1FPV
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: TheSteve on January 13, 2017, 02:52:11 am
Connect the main serial port to a terminal program and see what it says.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: K1FPV on January 13, 2017, 01:22:36 pm
I have and it is blank! Nothing with any of the programs, "Termite" a terminal program, nothing with U-Center, and nothing with "VisualGPSview" either. It appears to have pooped the bed! There is an LED underneath the main board that is flashing however.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: enaxy on January 13, 2017, 01:43:49 pm
Good point.  :-+
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on January 14, 2017, 09:42:01 am
Sigh, my view of the sky. Facing North from a ground floor condo, with trees around.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 14, 2017, 08:23:13 pm
Sigh, my view of the sky. Facing North from a ground floor condo, with trees around.

That's why I suggested that a GPS-disciplined Rb oscillator might be the best solution for you.  There are a few Rb oscillators that have GPS disciplining built-in.  Datum/Symmetricom X72 and SA22c, Stanford Research PRS10 are three that come to mind.  But be careful.  Some firmware versions don't have that feature.  Be sure to get confirmation from the seller that his units have the feature.  Unfortunately, these units tend to be at the higher end of the price scale.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on January 14, 2017, 09:07:14 pm
Yes, just don't have the view of the sky for a GPSDO (I do have a Rubidium) , just note that the plot I uploaded was from a older Nortel unit. My Symmetricom died on me. I do have a Jupiter-T that gives a much better plot. Out of curiosity does the Elevation strength plot mean that in this case that the strength is much better at 60 degress and perhaps upping the elevation mask may reduce some multi math interference.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 14, 2017, 09:34:23 pm
Out of curiosity does the Elevation strength plot mean that in this case that the strength is much better at 60 degress and perhaps upping the elevation mask may reduce some multi math interference.

I'd try setting the elevation mask low (0-10 degrees) and running it for a few hours so see where the signals start to really fall off.   In that plot it looks like around 40 degrees.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: bingo600 on January 15, 2017, 05:05:38 pm
Sigh, my view of the sky. Facing North from a ground floor condo, with trees around.

That's why I suggested that a GPS-disciplined Rb oscillator might be the best solution for you.  There are a few Rb oscillators that have GPS disciplining built-in.  Datum/Symmetricom X72 and SA22c, Stanford Research PRS10 are three that come to mind.  But be careful.  Some firmware versions don't have that feature.  Be sure to get confirmation from the seller that his units have the feature.  Unfortunately, these units tend to be at the higher end of the price scale.

Afaik the X72 needs fw > 5.x for 1PPS support , and i have 4.x on mine  :(

/Bingo
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 15, 2017, 05:41:36 pm
Sigh, my view of the sky. Facing North from a ground floor condo, with trees around.

That's why I suggested that a GPS-disciplined Rb oscillator might be the best solution for you.  There are a few Rb oscillators that have GPS disciplining built-in.  Datum/Symmetricom X72 and SA22c, Stanford Research PRS10 are three that come to mind.  But be careful.  Some firmware versions don't have that feature.  Be sure to get confirmation from the seller that his units have the feature.  Unfortunately, these units tend to be at the higher end of the price scale.

Afaik the X72 needs fw > 5.x for 1PPS support , and i have 4.x on mine  :(

/Bingo

I asked Symmetricom if I could get the file to flash the new firmware.  They said all I had to do was RMA the unit and include a check for $1100.

 :wtf:  :o  Aaarrrgghh!......My heart!!.......   ;)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: bingo600 on January 15, 2017, 06:01:35 pm
I asked Symmetricom if I could get the file to flash the new firmware.  They said all I had to do was RMA the unit and include a check for $1100.

 :wtf:  :o  Aaarrrgghh!......My heart!!.......   ;)

I know ... And got a PRS10 instead , for 25% of that silly price.
I was even lucky enough to inherit PHK's PRS10 adapterboard, from his dead unit.  :-+ :-+

BTW: I think i saw someone on *Bay offer to do the upgrade for "small money" , but he wrote it might brick in the process.

Bingo
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 15, 2017, 06:15:56 pm

I asked Symmetricom if I could get the file to flash the new firmware.  They said all I had to do was RMA the unit and include a check for $1100.


A few weeks ago there was a guy on Ebay offering to upgrade them for around $40...   I don't see his listing anymore.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 15, 2017, 08:08:30 pm

I asked Symmetricom if I could get the file to flash the new firmware.  They said all I had to do was RMA the unit and include a check for $1100.


A few weeks ago there was a guy on Ebay offering to upgrade them for around $40...   I don't see his listing anymore.

I think I saw that a few months ago, but there was something about it that I didn't like or it wouldn't work for me.  I can't remember for sure.  Maybe existing firmware had to be at least version X.X.  Maybe just the idea of international shipping (twice!) plus exchange.  Suddenly the price wasn't so attractive for something I didn't really need at the moment.  But it could be very interesting for Bryan if it pops up again on ebay.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 15, 2017, 08:15:05 pm
Maybe existing firmware had to be at least version X.X.

I think that he mentioned that he had upgraded certain firmwares but could probably do others.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on January 15, 2017, 10:11:48 pm
Here is the relative strength vs elevation after 24 hours. Not sure what the yellow marker at ~42 degrees means (It seems to move)?.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 15, 2017, 10:36:02 pm
Here is the relative strength vs elevation after 24 hours. Not sure what the yellow marker at ~42 degrees means (It seems to move)?.

The yellow marker is where the signal strength falls below 87.5% (75% on a Resolution-T) of the average signal strength.  Looks like an elevation mask setting of a little over 30 degrees would be appropriate for your receiver. 

When doing the "autotune" function Heather choses an elevation mask setting half way between the yellow and blue (current elevation mask) values.  It used to set it to where the yellow marker is,  but that seemed to be a little too conservative.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on January 15, 2017, 10:46:50 pm
Excellent, thanks for the information. The plots were for my Nortel, going to try the Jupiter-T receiver and see how it compares. it can see more satellites so hopefully will perform better with the view I have. I did try the autotune with LH4 and it returned a very high elevation mask. Tried the autotune on LH5 and it set the elevation mask at 21 degrees, but I assume it will change depending on the view at the time of the autotune. But yes, think 30+ degrees is the way to go.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 16, 2017, 02:19:35 am
These "UCCM" receivers only output a time code message every two seconds.  Currently Heather fakes the missing odd numbered seconds internally so that things like the audible clocks and alarms work (semi-)properly, but the clock displays only appeared to update every other second.  I was hacking around in the code and figured out a way to generate the faked seconds "on-time".  So now the clocks tick normally every second.

I also added the ability of Heather to talk to up to 10 external com devices (serial or TCP/IP).  One of the pre-defined com "ports" just echoes whatever comes from the receiver.  Another port can send a NMEA formatted stream of the receiver data.  These "echo" ports let you control, monitor, and configure the receiver and also send the receiver data (in native format or NMEA format) to another device or program like NTP, GPSD, etc. 

If one really wanted to, you could add code to echo the receiver data in any format that you wanted (like convert Trimble receiver TSIP data to Ublox format)... an exercise left to the reader...

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 16, 2017, 03:51:37 am
I also added the ability of Heather to talk to up to 10 external com devices (serial or TCP/IP).  One of the pre-defined com "ports" just echoes whatever comes from the receiver.  Another port can send a NMEA formatted stream of the receiver data.  These "echo" ports let you control, monitor, and configure the receiver and also send the receiver data (in native format or NMEA format) to another device or program like NTP, GPSD, etc. 

Would this allow you to run LH on the Tbolt's port and then run NTPD with refclock29 (Tbolt) against LH's virtual port?  Does that include the 1 PPS?  Any idea what kind of jitter/delay you'd see?  Delay could probably be adjusted for,  but jitter would be more of a problem.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 16, 2017, 04:48:16 am
Would this allow you to run LH on the Tbolt's port and then run NTPD with refclock29 (Tbolt) against LH's virtual port?  Does that include the 1 PPS?  Any idea what kind of jitter/delay you'd see?  Delay could probably be adjusted for,  but jitter would be more of a problem.

That's the idea...

Heather knows nothing about hardware 1PPS signals... there is no connection to the 1PPS signal.

Delay would be dependent upon your system and buffering delays.  If you are using a 1PPS signal, it should not matter to NTPD as longs as the message gets out before the next 1PPS pulse... which it should.  If you are not using 1PPS signal, you would need to compensate for the delay.  Jitter should be minimal in either case.

As the receiver data comes in Heather crams it into a buffer.  When the last byte of a message comes in, Heather processes the message and, for the echoed data, sends it out the echo port.

One could cause Heather to echo the unbuffered data as it comes in, but that is rather inefficient... particularly for TCP/IP connections... you would be sending lots of 1 byte packets.  You could reduce any delay by echoing the data at a higher baud rate.

I'm going to do some comparisons with the direct receiver data and echoed data tomorrow.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 16, 2017, 05:25:28 am
Would this allow you to run LH on the Tbolt's port and then run NTPD with refclock29 (Tbolt) against LH's virtual port?  Does that include the 1 PPS?  Any idea what kind of jitter/delay you'd see?  Delay could probably be adjusted for,  but jitter would be more of a problem.

That's the idea...

Heather knows nothing about hardware 1PPS signals... there is no connection to the 1PPS signal.

That's what I suspected, but I thought I'd ask.  The best NTPD performance is obtained by having the 1 PPS on one of the RS-232 control leads.  The Tbolt doesn't do this unless you do the hardware mod yourself, but other GPSDOs do.  If LH doesn't pass that on to its virtual port, NTPD will only have the ASCII to work from and won't provide its best performance.

God, don't tell me I'm becoming an NTP-nut too!  |O

Quote
Delay would be dependent upon your system and buffering delays.  If you are using a 1PPS signal, it should not matter to NTPD as longs as the message gets out before the next 1PPS pulse... which it should.  If you are not using 1PPS signal, you would need to compensate for the delay.  Jitter should be minimal in either case.

I'm confused.  If LH is connected to the hardware port, how could you use a 1 PPS signal for NTPD?

Quote
As the receiver data comes in Heather crams it into a buffer.  When the last byte of a message comes in, Heather processes the message and, for the echoed data, sends it out the echo port.

One could cause Heather to echo the unbuffered data as it comes in, but that is rather inefficient... particularly for TCP/IP connections... you would be sending lots of 1 byte packets.  You could reduce any delay by echoing the data at a higher baud rate.

You'd only use NTPD on the echo port, i.e. it would run on the same machine as LH.  Network delays, both fixed and variable would severely compromise the performance otherwise.  Other apps might find the timestamp via TCP/IP useful.

Quote
I'm going to do some comparisons with the direct receiver data and echoed data tomorrow.

Looking forward to it!  :-+

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 16, 2017, 07:36:40 am
The best NTPD performance is obtained by having the 1 PPS on one of the RS-232 control leads.  The Tbolt doesn't do this unless you do the hardware mod yourself, but other GPSDOs do.  If LH doesn't pass that on to its virtual port, NTPD will only have the ASCII to work from and won't provide its best performance.

You would just wire the 1PPS signal from the receiver to whatever pin your NTP expects.  For 1PPS in via the serial port (the standard pin used by NTP is the carrier detect line) you would wire the 1PPS signal to the the virtual com port connector CD pin.  Heather passes the data stream from the receiver through to the virtual com port which then feeds NTP.

For the serial data the flow is RCVR -> HEATHER RCVR PORT -> HEATHER VIRTUAL PORT -> NTP
For the 1PPS signal it is RCVR -> VIRTUAL PORT CONNECTOR CD pin-> NTP

If you are using a receiver that NTP understands, you could do much the same thing with just a serial "Y" cable and send the receiver serial output signal to both the Heather serial port and the NTP serial port.   But if you are using something like the UCCM receivers that NTP doesn't know about and that only send the time out every other second, Heather can generate a NMEA stream to feed NTP.

My intended configuration is to have a Raspberry PI with the 800x480 touchscreen controlling and monitoring the receiver and spitting out a NMEA stream and 1PPS for feeding NTP.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 16, 2017, 05:08:21 pm
Okay, thanks.

I think we've hijacked this thread enough.  I'll reserve any more questions until after the software is issued.

"We now return you to your regular programming".

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on January 16, 2017, 06:08:28 pm
Looking forward to it!  :-+

I did some testing.  Receiver was a Thunderbolt at 9600:8:N:1.  I measured the message timing offset (the difference between the time in the time code message and the time the last byte of the message arrived) and the standard deviation of the message arrival times.

Direct rcvr connection to Linux laptop:  msg_ofs:60 msecs     sdev:0.55 msecs
Direct rcvr connection to Windows XP:  msg_ofs:52 msecs     sdev:42.1 msecs

Echo TSIP from XP box to Linux box:  msg_ofs: 99 msecs   sdev:44.6 msecs
Echo NMEA from XP box to Linux box:  msg_ofs: 160 msecs    sdev:25.36 msecs

Echo TSIP from XP box to Linux box running GPSD:  msg_ofs: 373 msecs   sdev:28.5 msecs
Echo NMEA from XP box to Linux box running GPSD:  msg_ofs: 261 msecs    sdev:8.5 msecs
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on January 17, 2017, 03:37:38 pm
Here is the relative strength vs elevation after 24 hours. Not sure what the yellow marker at ~42 degrees means (It seems to move)?.

The plot of my Jupiter-T receiver shows quite an improvement, better receiver I suppose, can see 12 birds vs 8.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 17, 2017, 05:13:18 pm
Do you have equipment that can measure the jitter on the Jupiter-T?  Either the period of the 1 PPS or the time delay between the 1 PPS and your Rb.  Since the Jupiter-T has to pick up signals that come through the building, there's no telling how good the results will be.  The results could actually be worse than before if the Jupiter-T is accepting signals that are basically garbage.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on January 18, 2017, 02:04:15 am
The Jupiter-T is using the same antenna as the Nortel, just swapped the Nortel out to test (wasn't tested indoors). I have a DSO and suppose can use persistence mode and see how much the 1pps output varies. That good enough?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 18, 2017, 05:01:40 am
The Jupiter-T is using the same antenna as the Nortel, just swapped the Nortel out to test (wasn't tested indoors). I have a DSO and suppose can use persistence mode and see how much the 1pps output varies. That good enough?

I realize that both units are using the same antenna.  The problem is that by picking up weaker signals, the Jupiter-T might be picking up signals that are so crappy that they should be rejected.  By comparison, the relatively deaf Nortel unit doesn't see them at all.

Give the DSO a try.  Does the Jupiter-T include an OCXO or is it just a GPS receiver?  My experience is that a GPSDO has jitter of < 5 ns while a plain GPS receiver has jitter of 20 - 100 ns under good conditions.  A data sheet I found for the TU60 Jupiter-T GPS Receiver says that timing accuracy is typically 10 - 20 ns and then states that in position hold mode it's +- 40 ns.  That might be a worst case measurement.  If yours measures significantly worse, it's probably because of your poor sky visibility.  See how the Nortel compares and use whichever one gives the best results, regardless of what the graphs show.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on January 18, 2017, 07:50:54 pm
Yes, good point, that could very well be the case. The Jupiter-T is just a receiver with a 1pps and 10kHz output. Any suggestions as to properly test the jitter on the 1pps. Looking at a few tutorials and it is easy if you have a 100K scope<g> I can use the persistence mode on my DS1052e and monitor the rising edge of the 1pps pulse stretched across the display. 
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: edpalmer42 on January 18, 2017, 08:38:34 pm
Yes, good point, that could very well be the case. The Jupiter-T is just a receiver with a 1pps and 10kHz output. Any suggestions as to properly test the jitter on the 1pps. Looking at a few tutorials and it is easy if you have a 100K scope<g> I can use the persistence mode on my DS1052e and monitor the rising edge of the 1pps pulse stretched across the display.

You can't just look at the pulse, you have to look at the period of the 1 PPS.  So you'd have to trigger on the 1 PPS, but tell the DSO to delay the data acquisition for about 1 sec. so that you can see the rising edge of the next pulse.  The jitter on this rising edge will show you the quality of the output.  Maybe your DSO could measure the period of the 1 PPS and report that. 

If your DSO can't do this, you could trigger off of the 1 PPS on one channel and look at your Rb on the other channel.  But you'd have to tweak the Rb to be exactly on frequency, otherwise, the Rb signal will just walk across the screen and smear the results.

The best way to make this measurement is with a time interval counter that measures the time from the rising edge of the 1 PPS from the GPSDO to the rising edge of a signal (ideally 1 PPS) derived from the Rb.  Make many measurements, collect the data electronically, then process it with a program like Timelab.  I don't know if your DSO can be coaxed into doing something like that.  In the end, the results should look something like the attached.  The diagonal part on the left is due to limitations of the measuring equipment.  The flat part shows the performance of the OCXO.  Looks like the Trimble UCCM is okay, but nowhere near as good as the Z3801A.  Both graphs then turn and follow the "GPS line" which is the approximate performance limit of the GPS system.  Finally, at about 10K sec., the Rb starts to peek out from underneath the GPS line.  The black line would have turned and followed a similar path to the blue line if the data run had lasted longer.

Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: VK2AN on January 27, 2017, 09:48:25 am
Hi Everyone,

Not sure if this is the right place to post this question, but I have also recently bought a Symetricom board off Ebay. I seem to have been lucky as no broken caps, no missing sockets and the unit appears to work fine, but it has a couple of peculiarities.

I have mounted it in a case and brought the alarm and lock LEDs out to the front panel. I also have it connected to an ex telco GPS antenna (another Ebay purchase) and it locks fairly quickly and can see around 10 sats most of the time, but the Alarm led refuses to go out.

The ALAR:HARD? and ALAR:OPER? commands both come back "None" but the SYST:STAT? command  tells me it is "Settling"? It is still in this state after being on for more than 24 hours? The 10 Meg output seems quite stable and locked to 10Mhz (as far as I can tell)

Does anyone have any ideas how I can get the alarm led to go off?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: ekyle on January 30, 2017, 04:46:25 pm
I would check and see what the diagnostic log file says. DIAGnostic:LOG:READ:ALL? It might offer some clues.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: digital_dreamer on February 21, 2017, 03:48:11 pm
I'm building a monitor for my Trimble GPSDO based on a STM32F4 driving a 3.5" screen at 480x320. What a lot of fun.

So far, I'm receiving the TOD from the dedicated TOD USART entirely via DMA and interrupts - no loop. The alternate/fake seconds are filled in via counter/interrupt, as well. The most time consuming portion, besides waiting for data, is drawing to screen, obviously. But, I have it down to less than 240 microseconds per clock digit change and only updating the digits that changes.
The time is computed on the fly, converting the GPS seconds to UTC via Modified Julian Date. I'm amazed that the math to convert to MJD and back is only a few hundred cycles on the 168MHz MCU - hardly any time at all.
Leap seconds are added when available on the TOD stream.

I'm updating to the screen the PPS and DAC values each second, as well. The Sat data is split between POSSTAT and SYST:STAT?, alternating on each second. It seems the El and Az data is only available from SYST:STAT?, so you have to match the Sat ID/PRN from POSSTAT to the SYST:STAT? data. Can create messy issues if the data changes between the two USART transfers.

I'd like to create a plot of the DAC, PPS, and OSC, as well as a scattergram/skyplot as texaspyro has done in LH, but haven't quite got that down yet. texaspyro has done some amazing work with his software.

However, I got a whole bunch of questions to ask those that would know:


best regards,
MAJ

(https://dl.dropboxusercontent.com/u/1180773/GPSDO_screen.jpg)
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on February 23, 2017, 10:31:45 pm
I just added the capability of Heather to monitor and control a GPS device while simultaneously calculating ADEVs from an external time interval counter like the TAPR TICC  (it can also work with the time interval analyzer only).  This mode lets Heather calculate true adevs instead of "bogo-adevs" derived from the GPSDO self-reported control loop statistics.

As a test.  I connected Heather to a Trimble "UUCM" GPSDO and a TICC.  The TICC channel A is the UCCM and channel B is a Oscilloquartz Star-4 GPSDO.  The TICC reference is a ERC-130 rubidium (uses an LPRO-101.  Attached is a screen dump of a 12 hour run.  The UUCM beats the Star-4 at tau<20 seconds.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on February 23, 2017, 11:03:34 pm
Wow, that's excellent. How does the external counter connect?
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: texaspyro on February 23, 2017, 11:25:43 pm
Wow, that's excellent. How does the external counter connect?

The TAPR TICC (https://www.tapr.org/kits_ticc.html (https://www.tapr.org/kits_ticc.html)) is a small, cheap ($200) two channel time interval counter with 60 ps resolution.  It uses an Arduinio 2560 for its processor and outputs data via USB.   A commercial, single channel counter with that kind of resolution will set you back a few grand.

Heather now supports time interval counters.  It can either run the TICC as the main input device (instead of a GPS receiver) or as an auxiliary input device (while monitoring and controlling s GPS receiver).  The code supports up to 4 TICC channels simultaneosly.  Currently it works with either time stamping counters or time interval counters.  The TICC reader code can handle the TAPR TICC,  the HP5313x, or a generic time interval/time stamping counter.

Here is screen dump of it running in stand-alone mode and displaying the four different adev type of an Oscilloquartz Star-4 GPSDO.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: Bryan on February 23, 2017, 11:33:12 pm
I got a full refund when the trimble unit I ordered from him didn't show. It did arrive after 2 + months finally, and had a few small caps ripped off the board.

Well against my better judgment I went and ordered a 65256 from this seller. Arrived yesterday, poor condition, dirt and oil all over it, OCXO is speckled with rust and corrosion. Hooked it up to 5.5v to start with, nothing from the output either 10MHZ or 1pps ( well ok 20mv on the 10MHz output), let it sit for awhile, current dropped from about 2 amps to over 1 and still nothing.Then I noticed the DSP TSM320 was just cooking. Yup, it's probably dead. Didn't even bother with seeing what it shows up on the PC as it surely will be a disappointment.
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: digital_dreamer on March 11, 2017, 07:18:57 am
Got a question regarding the UCCM-P Trimble GPSDO, if you guys don't mind.

When up and running the TFOM is typically at 2, which is 10-100ns.
Now, I've noticed the PPS time interval will frequently get much better than that, usually around 1ns or better. So, why does't the TFOM drop down to a lower number, like "1" during this time?
I notice during a reset, the TFOM is well in line with the PPS Time Interval. But, once the TFOM gets to 2, it'll never go lower, even if the time interval is 1ns or less.

Any insight on this? Is my understanding woefully incorrect and off in another galaxy?
Would it be proper to override this if developing a GPSDO software monitor?

best regards,
MAJ
Title: Re: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)
Post by: lachesis on May 10, 2017, 02:17:52 am
I think mine is dead too. I bought it back in January but didn't get around to testing it until this week, so it looks like I'm out of luck with eBay. The seller listed it as "tested working" as well. I hook it up and let it complete its survey of the sky, but it never enabled the output. Oddly, it reports that everything is fine (except LINK is unavailable).

I can get the output to come up if I do DIAG:OUTP ON, at least sometimes. This makes the left LED switch to flashing GREEN & YELLOW. My scope thinks this is a 10MHz output, but since it wasn't autoenabled, I suspect the reference is not happy with the output.

The OXCO has a nice 1.5V P-P signal on its output pin. The board looks alright - no obvious components ripped off or anything like that.

My suspicion is that the OXCO has drifted outside its range, but I'm not 100% sure about that. Does anyone know which pin I should measure to find its adjustment voltage, and what the relationship between that voltage and the change in frequency should be? The OXCO is labeled Trimble 65256.

Here's some logs:
Code: [Select]
UCCM >DIAG:LOG:READ:ALL?

Log status:  14 entries

L00:17/05/10.01:53:25 Reset board by preset command
L01:99/08/22.00:00:01 Output mode: Alarm
L02:99/08/22.00:00:01 Power up start
L03:99/08/22.00:00:01 A/S change: Slave(HIGH)
L04:99/08/22.00:00:01 REF_SEL change: LINK(HIGH)
L05:17/05/10.01:59:13 Ref available
L06:17/05/10.02:00:14 Ref Change: GPS
L07:17/05/10.02:00:15 Ref chang: External PPS
L08:17/05/10.02:04:00 Reset board by preset command
L09:99/08/22.00:00:01 Output mode: Alarm
L10:99/08/22.00:00:01 Power up start
L11:99/08/22.00:00:01 A/S change: Slave(HIGH)
L12:99/08/22.00:00:01 REF_SEL change: LIN