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

[ekyle]

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.

[deepskyridge]

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

[sharpgun]

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.......

[deepskyridge]

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

[texaspyro]

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.

[Macbeth]

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.

[sharpgun]

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

[Nuno_pt]

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.

 

[deepskyridge]

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

[texaspyro]

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.

[deepskyridge]

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

[Nuno_pt]

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.

[Nuno_pt]

For those that are thinking of buying or making an distribution amplifier for 10MHz, look at this video from Gerry https://youtu.be/chrzrod3tQY, or this other guy that use a smaller version 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.

[sharpgun]

 O0Hi, anybody know how to connect to GPS GT-8031F? Whice Pin is RX TX.... TTL or  RS232..............Show me the Picture....3Q

[Nuno_pt]

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.

 

[sharpgun]

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

[Nuno_pt]

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.

[Nuno_pt]

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?

 

[jkf1000]

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

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

[davebb]

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

[jkf1000]

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

[Nuno_pt]

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.

[jkf1000]

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

[Nuno_pt]

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.

[dl2sba]

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


//Dietmar