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

[PA0PBZ]

I hava a UCCM-P GPSDO.
I want to decode the TOD message send by GPSDO every 2 seconds over serial port in order to make a real time clock
An example message below:
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 4A DA 3D 9A 00 12 60 04 45 80 00 00 00 00 4E 0F CA
Thank you in advance

Same thread: https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg967799/#msg967799

[tomeo.gonzales]

Thank you.
It was exactly what I need.

[thinkfat]

Alright, got mine to talk to Lady Heather with a RS232 USB converter. The problem now is it's not seeing any satellites. I've connected some GPS antenna I bought off Ebay, I found one that has a MCX connector so that I could hook it up directly to the socket on the PCB.

The antenna is recognized, i.e. I don't get an alarm signal on the ALM led (it's off) when the antenna is connected.

I can measure 5V on the "cold" side of L2.

Probably the antenna position is not good. I put it on a sheet of metal with it's magnetic back, but it's inside on a west facing window on the window sill. I guess I need to find a better place for it.

[thinkfat]

Status output:

Code: [Select]

UCCM > stat

                 - UCCM-LP Slot STATE -



1-1. #Now UCCM-LP STATUS --------------- [Wait for GPS]
1-2. #Before UCCM-LP STATUS ------------ [OCXO Warmup]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [GPS]
2-3. #Current Select Reference --------- [NOT SELECT]
2-4. #Current Reference Status --------- [Not Selected]
     #GPS STATUS ----------------------- [Unavailable]
     #ALARM STATUS
     #H/W FAIL ---------- [ EXT ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [OFFSET OBSERVATION MODE]
Command Complete

I'm wondering mostly about "#GPS STATUS [Unavailable]"

Code: [Select]

UCCM > syst:stat?
-------------------------------------------------------------------------------
090-03861-13   serial number S3ZB720551   firmware ver 1.0.0.5-01      Ext mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
XX Ref Ext :                                 
                                              TFOM     9             FFOM     3
                                              UCCM-LP Status[WAIT FOR GPS]
                                             
>> GPS: [no ref]                             
ACQUISITION .............................................. [ GPS 1PPS Invalid ]
Tracking: 0 ____   Not Tracking: 0 ________   Time ____________________________
                                              GPS      00:17:54 [?] 06 JAN 1980
                                              GPS      Invalid: not tracking
                                              ANT DLY  +0.000E+00
                                              Position ________________________
                                              MODE     Survey:      0% complete
                                                       Suspended: track <4 sats
                                              INIT LAT N  49:48:51.000
                                              INIT LON E   8:39:10.998
                                              INIT HGT          +96.00 m  (MSL)
                                             
                                             
                                             
                                             
ELEV MASK  5 deg                             
-------------------------------------------------------------------------------

Command Complete

What does "GPS [no ref]" mean?

[PA0PBZ]

I'm wondering mostly about "#GPS STATUS [Unavailable]"

What does "GPS [no ref]" mean?

I think this is because it didn't receive anything (yet).

[thinkfat]

I'm wondering mostly about "#GPS STATUS [Unavailable]"

What does "GPS [no ref]" mean?

I think this is because it didn't receive anything (yet).

Yes, you're right. I cobbled together a power supply and moved the whole setup including the laptop out in the garden and let it run for a while, and it locked and completed the survey without problems, within 90 minutes or so. I'm now back in the lab and I've just put the antenna outside on the window sill, it's working just fine and doing the survey again.

Looks like I have a fully functional unit. Considering the horror stories I've read about ripped off components and stuff, I consider myself very lucky. The device I have here looks pristine.

[thinkfat]

OK, pretty happy with the first results, I let the unit run overnight, but it really deserves to be in a housing of sorts, it was just laying on by bench. Every little draft of air probably influences the OCXO.

Is there a way with these receivers to make a longer survey than the built-in self survey? It always completes in 1 hour, but I would give it a bit more time for a more precise position. Lady Heather supports that, but the GPS automatically goes into "position hold" after the survey completes and in that mode the reported position is constant.

Also, how big is the influence of the satellite constellation on the time accuracy and stability? It doesn't have a real good view to the sky, basically it can see the western hemisphere only.

[thinkfat]

Attached a screenshot from Lady Heather after having it run overnight.

[PE9RX]

So i got an Samsung device instead of the Symetricon.
Not so much difference i gues, both have a OCXO and both have a GPS.
I figured out the Serial port, baudrate and gave some commands and status update with Putty.
It is recognized by Lady Heather, but she shows no data on the screen, but the data is flowing (sniffer).
Maybe not supported yet i gues..

Already figured out that the command do not are retentive, so after every powercycle you need to do some settings.
Like in my case where the standard settings are  not usable.

       - UCCM Slot STATE -

1-1 #Now UCCM STATUS ----------------------------[Alarm]
1-2 #Before UCCM STATUS -------------------------[OCXO Warm]
2-1 #Reference Clock Operation ------------------[Not Used]
2-2 #Current Reference Type ---------------------[Ext Clock]
2-3 #Current Select Reference -------------------[NOT SELECT][Ext ?]
2-4 #Current Reference Status -------------------[Unavailable]
    #GPS STATUS ---------------------------------[Unavailable]
    #Priority Level -----------------------------[EXT->GPS]
    #ALARM STATUS
    #H/W FAIL -----------------------------------[NONE]
    #OPERATION ALARM ----------------------------[EXTREF]
    PLL STATUS ----------------------------------[Disable]
    Current PLL MODE ----------------------------[OFFSET OBSERVATION MODE]
"Command Complete"


So i know now i need the commands:

sync:ref:disable ext
sync:ref:enable GPS
Ref:Type GPS

I can have a arduino do that for me, maybe even a display handler to get the status on a display.

Stat after these commands:

1-1 #Now UCCM STATUS ----------------------------[Alarm]
1-2 #Before UCCM STATUS -------------------------[OCXO Warm]
2-1 #Reference Clock Operation ------------------[Not Used]
2-2 #Current Reference Type ---------------------[Ext Clock]
2-3 #Current Select Reference -------------------[GPS 1PPS]
2-4 #Current Reference Status -------------------[Available]
    #GPS STATUS ---------------------------------[Available]
    #Priority Level -----------------------------[EXT->GPS]
    #ALARM STATUS
    #H/W FAIL -----------------------------------[NONE]
    #OPERATION ALARM ----------------------------[Antenna]
    PLL STATUS ----------------------------------[Enable]
    Current PLL MODE ----------------------------[FAST LOCKING MODE]


Still have to figure out what the ANTENNA OPER alarm is about.
GPS is locking etc so no big deal i gues.

for the rest everything looks good:
 UCCM> syst:stat?
-------------------------------------------------------------------------------
UCCM-L8  serial number SE2D307230  firmware ver 1.0.0.3-02 GPS(or Ext) mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
XXExt Ref : Unknown[LOS]
                                                                             TFOM     2            FFOM      1
                                                                             UCCM A Status[Master]

>>GPS :     [phase : -6.500E-8]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking:  5 ___   Not Tracking:  6 _______   Time ____________________________
PRN  El  AZ  CNO   PRN  El  Az                       GPS      23:01:40     19 NOV 2019
  2  31  53  43      6   4  24                           GPS      Synchronized to UTC
 12  23  94  44     14  26 254                        ANT DLY  +0.0E+0
 25  69  91  49     21   4 182                         Position ________________________
 29  74 199  50     23   1 347                        MODE     fixed
 31  55 287  48     26  17 282
                    32  12 228                              FIX LAT  N  52:xx:xx.xxx
                                                                  FIX LON  E   4:xx:xxx.xxx
                                                                  FIX HGT           +43.97 m




ELEV MASK  5 deg                              ANT V=5.148V, I=16.160mA
-------------------------------------------------------------------------------
Temp = 34.000 / Antenna
"Command Complete"


Anything else to do or to take care of?
all hints would be appreciated..

[thinkfat]

I believe I have the same model, bit different firmware, though. Lady Heather supports it, at least the 6.14 beta does. Try starting with /rxcs.

Try diag:log:read:all? to display the log. Might give a clue about the alarm.

[PE9RX]

Lady Heather supports it, at least the 6.14 beta does. Try starting with /rxcs.

Oke that is the problem. i could only find the 5.00 release.
Any idea where i can find the 6.14 beta for windows??

[PA0KTF]

https://www.eevblog.com/forum/metrology/lady-heather-v6-beta-for-windows-exe/

[jailbird]

I know this is a really stupid question guys, please be gentle .

I know most people are using 40-42 for GND & some/all of 44-50 for for +5V.   The question is what to do with the rest of the (signal) GNDs?  Should they all be bridged?  I'm guessing no, but I figured there's a reason that they're exposed in the first place...

Thanks!

[thinkfat]

They're all bridged on the module anyway.

[jailbird]

They're all bridged on the module anyway.

Awesome, thanks! I assumed so, but...

[MKatana]

Hi everyone!

I bought one Samsung STP 2945 LF and one Trimble 57964-05 UCCM board.
The Samsung one had it's DAC set at 100% without locking and gave out "EFC Limit Exceed" error so I replaced the OCXO with a Bliley one and suprizingly the thing worked right away!
It still throws a power alarm using 6V with the pin 39 floating.
57964 on the other hand locks fine but LH doesn't seem to get any LOOP data out of it.
Serial monitor shows that mine doesn't understand some of the commands.

[texaspyro]

It still throws a power alarm using 6V with the pin 39 floating.

Try a silicon or  Schottky diode as a voltage dropper.   The Samsung valid input voltage detector is rather picky...

[thinkfat]

Make sure you have all supply and ground pins connected. The FPC cable has a significant burden voltage. If connected properly, 5.5V at the source is sufficient.

[MKatana]

It still throws a power alarm using 6V with the pin 39 floating.

Try a silicon or  Schottky diode as a voltage dropper.   The Samsung valid input voltage detector is rather picky...

I'll fiddle with the MP1484 buck converter feeding it.

Make sure you have all supply and ground pins connected. The FPC cable has a significant burden voltage. If connected properly, 5.5V at the source is sufficient.

So far I have used all 7 5V pins and only 3 GND pins for power. I'll make shure to connect the other grounds.

57964 didn't show that it has locked after powering it last night. The graphs and reported parameters look fine. Any ideas?

[thinkfat]

It still says "warming up". It's not going to go into lock in that state. Also, observe that the TCOR line is flat. You have a problem with the temperature sensing circuit for the OCXO. You exchanged the original (broken?) OCXO with another one, right? That might also mean the temperature compensation params inside the unit are useless now. Not sure if it's worth continuing.

All other parameters look fine (TFOM 2, FFOM locked), no problem with the GPS part of the unit.

EDIT: No, the one you exchanged was the OCXO on the Samsung module, I misread this.

[thinkfat]

BTW in case anyone's interested, I made a power supply and signal breakout board for these UCCM modules. You can read a bit about it here:
https://www.eevblog.com/forum/projects/question-on-buck-converter-layout/msg2818976/#msg2818976

If anyone's interested, I can supply Gerbers and a BOM. Soldering is probably not too difficult, just the FPC connector is a pain. All components are 0805 or larger, all doable with a decent soldering iron. The switching regulator however has a center pad that needs a hot-air station to reflow correctly. You can also solder it from the bottom side with a decent amount of heat and additional flux.

The PCB fits into a Fischer KOH case.

[Sparky]

BTW in case anyone's interested, I made a power supply and signal breakout board for these UCCM modules. You can read a bit about it here:
https://www.eevblog.com/forum/projects/question-on-buck-converter-layout/msg2818976/#msg2818976

If anyone's interested, I can supply Gerbers and a BOM. Soldering is probably not too difficult, just the FPC connector is a pain. All components are 0805 or larger, all doable with a decent soldering iron. The switching regulator however has a center pad that needs a hot-air station to reflow correctly. You can also solder it from the bottom side with a decent amount of heat and additional flux.

The PCB fits into a Fischer KOH case.

Nice work!  I am building a power supply module for the exact same GPSDO!   I will post some details of my approach in the thread you linked above!

[MKatana]

If anyone's interested I opened the failed Samsung OCXO.
Interestingly the 20 pin QFN chip is a Intersil ISL22446 SPI controlled quad 128 step potentiometer.

[Leo Bodnar]

Do you have the picture of the oven controller?  Looks like there was intention to go digital in that department.
Leo

[MKatana]

Do you have the picture of the oven controller?  Looks like there was intention to go digital in that department.
Leo

The oven controller seems to be made of discrete analog components.
There are seven SOT-23 ICs. Five are labeled "VBGI" and I guess those are TLV2371IDBVR, TLV237x opamps,
one "LOTB" LP2985-N LDO and one "C26K" SN74LVC1G126 buffer gate.

It seems that they did plan to add some digital functionality as the extra two pins go to the unpopulated QFN pad.
I guess the DPOT is used as a sort of factory calibration device because the wipers are set from it's programmable non-volotile registers at startup.