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

[texaspyro]

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.

[uncle_bob]

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

[DDalton]

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.

[f1rmb]

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...) 

[texaspyro]

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.

[shinjiikari0601]

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.

[texaspyro]

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.

[shinjiikari0601]

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.

[texaspyro]

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.

[Vgkid]

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...

[Macbeth]

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...

[ekyle]

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.

[sharpgun]

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
-------------------------------------------------------------------------------

[uncle_bob]

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

[sharpgun]

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....

[texaspyro]

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.

[sharpgun]

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....

[uncle_bob]

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

[sharpgun]

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

[sharpgun]

Power Supply 6.5v .....the OCXO test Voltage is
1. Power  5.77
2. VRef 2.80
3. EFC 2.80

is OK?

[uncle_bob]

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

[Vgkid]

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.

[deepskyridge]

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

[ZigmundRat]

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.

[sharpgun]

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 ??