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

[DM4DS]

After 24 hours - the survey is complete and many things looking good , some I´m still strugling.

First the good things:

Code: [Select]

                 - 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 ----------- [GPS]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [GPS > LINK]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [NORMAL 2 MODE]
Command Complete

Code: [Select]

POSSTATus
-----------------------------------------------------------------------------
11/29/2020 18:08:25
-----------------------------------------------------------------------------
 Position : LAT(N 49:XX:X.X54) LON(E 8:XX:XX.314) H(1X.40 m MSL)
-----------------------------------------------------------------------------
 Geometry : PDOP(0.0) HDOP(0.0) VDOP(0.0)
-----------------------------------------------------------------------------
 Channel Status
   num of visible sats > 9
   num of sats tracked > 3
   ------ Receiver Channel State ------
     CH 0 >  SateID(12) TrackMode(pos avail) SigValue(40)
     CH 1 >  SateID(25) TrackMode(pos avail) SigValue(37)
     CH 2 >  SateID(32) TrackMode(pos avail) SigValue(43)
     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(2) :
-----------------------------------------------------------------------------
  Antenna Voltage: 4941 mV,  Antenna Current: 17 mA
-----------------------------------------------------------------------------
Command Complete
Tryed to place the antenna better but no real difference.
Maybe there is a problem

Code: [Select]

SYSTEM:STATUS?
-------------------------------------------------------------------------------
090-03861-03   serial number W5609120308   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
XX Ref 8KHz 0: [LOS]                         
                                              TFOM     2             FFOM     0
                                              UCCM-P Status[ACTIVE]
                                             
>> GPS: [phase:  5.83e-08]                   
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 4 ____   Not Tracking: 5 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      18:09:02     29 NOV 2020
 10  11 274   31     6  10  94                GPS      Synchronized to UTC
 12  65 246   33    15  23 182                ANT DLY  +0.000E+00
 25  25 247   37    17  28  47                Position ________________________
 32  21 315   43    19  42  65                MODE     Hold
                           24  78 117               

                                              LAT      N  49:XX:00.054
                                              LON      E   8:XX:XX.314
                                              HGT              +1X.40 m  (MSL)
                                             
                                             
                                             
                                             
ELEV MASK 10 deg                             
-------------------------------------------------------------------------------

Command Complete
1 PPS turned to VALID , thats a real good news.

It report operational normal, but I can´t really believe. Why? If I measure the Vref Pin it´s always 4V. Instant after PowerUP. With 2 OCXOs I tryed and it never changed. On my selfbuild one this V is changing at the beginning fast , slowing down until perfect Lock. And 2 OCXOs who have the same "age Voltage".

Started a stability measerement on my Freq counter. it runs on his internal OCXO atm while it was easier to handle for the moment.

What exactly happens during the survey? Think this will answer my next question possibly too. Is there a way to disable the survey if it is not necessary everytime?

I ask while my selfbuild one is fired up every morning and only needs ~10-15 minutes for lock. If the survey is needed to be stable on the symmetricom then I can´t switch it off , it needs too long.

Have seen that some have other firmware, do we know the differences and can it be updated if it make sense?

The Thread is long, tryed to read alot and hope that I have not overread all the infos.

Hope all had a nice sunday and thanks for all the help.

[PA0PBZ]

Vref should be stable because it is a reference voltage created by the OCXO. You are confusing it with EFC which is the tuning voltage.

[DM4DS]

You are right Paul, thanks.

Not my dialy business.

The ENE doesn´t have the Vref , is it then usable? I read at side 46 i think that a OM tryed to use it.

Any answers on the survey?

[PA0PBZ]

Hi,

Not my daily business either
The survey is there to get the location as exact as possible. I could be helped by setting the location after powering up by using a command which I can't remember at the moment but it's in this thread somewhere... The best of course is to leave it powered on because after the survey it also takes some time to get the loop stable, I guess this could well be several hours if not days. Also, try to get Lady Heather working so you can have a nice overview of which part of the sky is covered by your antenna. I'm not sure what you are referring to by ENE, but if this is an OCXO without the Vref it would not be useable with the UCCM.

[wkb]

You could supply a stable reference of your own if the OCXO does not supply one itself. I have some OCXO's like
that here

[ZigmundRat]

Refer to my post from 4 years ago (where did THAT time go, eh?)
I think that will give you what you need to set the position and maybe answer some other questions. Your signal levels still look low though.

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.

[DM4DS]

I bought 5 ENE3311A some years ago but they don´t have the ref Voltage.
But if a small LT6654 can do the job, why not. Thanks

You could supply a stable reference of your own if the OCXO does not supply one itself. I have some OCXO's like
that here

I also have one Trimble OCXO which should also have the Vref . It´s too big to be soldered onto the symmetricom Possible that I give some wire a try.

Refer to my post from 4 years ago (where did THAT time go, eh?)
I think that will give you what you need to set the position and maybe answer some other questions. Your signal levels still look low though.

Thanks. The Thread is so long, nearly impossible to keep all in mind or find everything again if you dont spend hours....´
Will also try to do the Display thing I read somewhere.

On my own I did that in the past and works great.



Lady is working on this one. On the other one still no working RS232.
A Samsung one is also on the way, hope to get that also sorted....
LH is fine during testing etc but later my SYM will run behind my measure equipment and will not be connected to a PC.
The display could be a thing I build. a Small arduino and a 24x4 display should do the job.
Then the small arduino can also send the commands from "ZigmundRat" if it will be disconneted by any reason.

Hi,

Not my daily business either
The survey is there to get the location as exact as possible. I could be helped by setting the location after powering up by using a command which I can't remember at the moment but it's in this thread somewhere... The best of course is to leave it powered on because after the survey it also takes some time to get the loop stable, I guess this could well be several hours if not days. Also, try to get Lady Heather working so you can have a nice overview of which part of the sky is covered by your antenna. I'm not sure what you are referring to by ENE, but if this is an OCXO without the Vref it would not be useable with the UCCM.

[Bad_Driver]

Hi

I'm a new club member here. I got a cheap SYMMETRICOM UCCM board without OXCO (I have several double oven OXCOs
by the hand) at ALIEXPRESS (18€). It arrived in very good condition, nothing missing, nothing broken but a little bit oily.
The board is the same revision as the first ones in this blog.
I'm experienced with GPS receivers and GPSDO stuff.
From my shelf I got an old docking station for a much older HP laptop with a real RS232 interface.

After de-oiling ande using a TRIMBLE OCXO with different pin layout on a separate board I fired the UCCM up. Everything looks good,
all voltages are ok.
But after trying now for several days never a Satellit shows up! I tried several (working) antennas, inside and outside which all
find enough Satellites after a few minutes with my other receivers.

I went several times through the whole board but can't find any hint what to do.
Can some one be so kind and have a look on the following status messages maybe I have overseen something important.
Thanks in advance!

B.D.

11:19:12: SYST:STAT?
-------------------------------------------------------------------------------
090-03861-03   serial number W560940154   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS 0%]                       
                                              TFOM     9             FFOM     3
                                              UCCM-P Status[ALARM]
                                             
>> GPS: [no ref]                             
ACQUISITION .............................................. [ GPS 1PPS Invalid ]
Tracking: 0 ____   Not Tracking: 0 ________   Time ____________________________
                                              GPS      05:46:19 [?] 06 JAN 1980
                                              GPS      Invalid: not tracking
                                              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                             
-------------------------------------------------------------------------------
Alarms:  [0008] 10MHZ
Command Complete
UCCM-P >
UCCM-P > POSSTATUS
11:19:41: POSSTATUS
-----------------------------------------------------------------------------
1/6/1980 05:46:30
-----------------------------------------------------------------------------
 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: 4745 mV,  Antenna Current: 35 mA
-----------------------------------------------------------------------------
Command Complete
UCCM-P >
11:21:28: DIAGnostic:LOG:READ:ALL?
Log status: 22 entries

L1:1980-01-06 00:01:00:Log cleared
.... (removed - entries from the previous boot)
L13:1980-01-06 00:00:02:Power On
L14:1980-01-06 00:00:03:FPGA VCXO Alarm
L15:1980-01-06 00:00:03:OCXO Alarm
L16:1980-01-06 00:00:03:Funct Fail code: 00000208
L17:1980-01-06 00:00:03:Funct Fail OCXO curr: 400 mA
L18:1980-01-06 00:00:03:Funct Fail PDOP: 0.00
L19:1980-01-06 00:00:03:Funct Fail sat count: 0
L20:1980-01-06 00:00:03:Funct Fail TRAIM: 0 0
L21:1980-01-06 00:14:01:Antenna feed line fault (comes from changing antenna once again)
Command Complete
UCCM-P >

[DM4DS]

@ Bad Driver: Looks like mine , from time to time it receive some sats, then again none. Yours never, ok ,thats worse

Mine has now a new problem. Internal 0.5hz failure.
@PA0PBZ described that problem on the first pages here. But all looks good on my board . I have a stereo microscope able to solder 0201 but I can´t find any problem. All looks good, some points/joints I resoldered just to be sure that all is fine but it does not fix the problem.

No luck with these boards.

My first one runs but the RS232 is broken. The second, now has the 0.5 internal.....should I try to order a third one? All good things are 3

Or is one for sale?
These boards costs me time I could spend for other things 

[wkb]

I have a Symmetricom board that works. PA0PBZ verified it for me using
an original Symmetricom OCXO. I do not have the correspnding
Symmetricom OCXO myself.

Given that in the meantime I have acquired a nice complete working Samsung UCCM
as well as a (for now ai hope..) not locking Trimble UCCM my Symmetricom board
is up for sale. At cost of course, I think it was like €18 or so, would need to check
Send me a PM if you are interested.

Wilko
(trying not to get bitten by the Frequency Nuts bug.  Hmmm mulitple GPSDOs
and a Rubidium ref... argh..)

[Bad_Driver]

Thanks for your replies!
I assume that the GPS receiver doesn't work so I'll try to get soldered 2 wires on the RX/TX pins of it
and try to "listen" what's going on as described in the beginning of this topic.

And thanks for your offer Wilco, I keep it in mind. But first I try to get a new one from the Aliexpress dealer, he shows 900+ more in stock.
I never had any problems with delivery from China and it seems that Aliexpress is much faster than the EBay resellers.

I prepared a nice enclosure with 2 different PSUs for 5V and 12 V. I found in a Trimble Thunderbold board the hint that
performance and phase noise becomes much better with a separately analogous 12 V PSU for the OCXO which should be
also better on a different board to avoid digital interferences. But this makes only sense with a very good OCXO.

Would be a pity not to get a Symmetricom UCCM running 

I keep you all informed. If someone knows how to check with the UCCM console the status of the GPS receiver plz let me know.
Since my eyes are weak and my hands are trembling I'm not sure how successful my soldering efforts will be 

[PA0PBZ]

If someone knows how to check with the UCCM console the status of the GPS receiver plz let me know.
Since my eyes are weak and my hands are trembling I'm not sure how successful my soldering efforts will be 

It's not that bad to do and you only need one wire on the TX output of the receiver.

[Bad_Driver]

After soldering a UART to the GPS receiver pins I kept running the GPS logging the whole night. No Satellits!

$GPGGA,124539,3444.0000,N,13521.0000,E,0,00,00.00,000000.0,M,0036.7,M,,
$GPGSA,A,1,,,,,,,,,,,,,00.00,00.00,00.00
$PFEC,GPtps,020101124539,1,0,1,000000000000,00,00,000000000000,1147,218739

The FURONO receiver is still on it's initial position following to it's manual.

https://furuno.box.com/s/gmpma0cfol7xkxrhc85k9432c01uv6ep

I will now check once again the antenna connections on the board. May be I have overseen something.

The chinese seller Aliexpress seems not to be helpful. They expect a return of the board but postage is 16€ - senseless
for a 18€ item.

Mmh ... at ALiexpress are several Samsung UCCM for sale for about 50€...

[wkb]

I have a similar senseless discussion with an AliExpress seller about a Trimble UCCM that nicely sees GPS sats but never leaves the "Settling" state  . We simply do not have state-sponsored shipping here in Europe so "please return it" does not make any monetary sense. NL postage is even quite a bit higher than in Germany  :-(

Wilko

[Bad_Driver]

After removing the small onboard pigtail connector that runs from the GPS receiver to the motherboard and
connecting an antenna direct to it I hoped for any improvement - nothing. No satellite shows up 

Surprisingly I found that the FURUNO has it's own antenna feeding (4.8 V) independly from the feeding from the motherboard.

 11:08:23: $GPGGA,151641,3444.0000,N,13521.0000,E,0,00,00.00,000000.0,M,0036.7,M,,
$GPGSA,A,1,,,,,,,,,,,,,00.00,00.00,00.00
$PFEC,GPtps,020101151641,1,0,1,000000000000,00,00,000000000000,1147,227801

Same situation.

Wilko, that's the risk with this cheap deliveries from China, but to be honest it is the first time I run into trouble.
All my double oven OCXO came from Aliexpress and all perform very well. One of this Trimbles is now
the high stability time base of my HP 53131A and doing very well.

[DM4DS]

If you need something small soldered, let me know. I can do it for you.

Possibly you are in my area, then no shipping is required....76669

......
Since my eyes are weak and my hands are trembling I'm not sure how successful my soldering efforts will be 

[Bad_Driver]

Thanks for your interest and your offerings! But I worked it out by myself 
As mentioned I successfully soldered the UART to the  FURUNO pins on the motherboard and attached
the small pigtail from the GPS modul direct to my best 26 dB GPS antenna. The Furuno has it‘s own
antenna feeding.
But after another night nothing was received  Same receivers response as above.
And that is really a pity because the board arrived in very good shape, nothing missing or broken.

I‘m now sure that the GPS  part ist dead. May be I find the single Furuno elsewhere.

Aliexpress was not helpfull but I‘m now in contact with the seller (Pyboard Store) let‘s see. If he has another 900+ on stock
he should send me a replacement. (all fingers crossed).
And as far as I can see this is the only place in the web where they can find other buyers for their stock of UCCMs.

[wkb]

After some back and forth the AliExpress arbiter can up with a €17 refund. Better that than nothing at all, so I accepted.

Some measurements revealed the Trimble OCXO does not produce any Vref.  I have another Trimble OCXO here but that is a 12V iso a 5V. 

Will try the 5V Bliley, that appears to even fit the footprint on the PCB.

Stay tuned..

Wilko

NB the Symmetricom OcXO-less but working PCB is on its way to Germany, to DM4DS, so to a good home 😃

[wkb]

Sofar, with the Bliley OCXO installed, the Trimble UCCM ramains in "Settling" state. Which is the same thing that happened with the original ztrimble OCXO installed. 

Doe anyone per chance have a description of what the various states in LH mean? I could dig into the Lh source code but I'd rather not.

Wilko

[cdev]

Sometimes you can find TruePosition GPSDOs for around $35-45 online. And they contain a suitable Furuno TRAIM-enabled timing GPS.

That's a hell of a good deal.

(Although I would just leave it in the state you get it in. It might give you ?? (1? 2?) orders of magnitude improvement in accuracy).

But then you don't get to build it yourself.

Thanks for your interest and your offerings! But I worked it out by myself 
As mentioned I successfully soldered the UART to the  FURUNO pins on the motherboard and attached
the small pigtail from the GPS modul direct to my best 26 dB GPS antenna. The Furuno has it‘s own
antenna feeding.
But after another night nothing was received  Same receivers response as above.
And that is really a pity because the board arrived in very good shape, nothing missing or broken.

I‘m now sure that the GPS  part ist dead. May be I find the single Furuno elsewhere.

Aliexpress was not helpfull but I‘m now in contact with the seller (Pyboard Store) let‘s see. If he has another 900+ on stock
he should send me a replacement. (all fingers crossed).
And as far as I can see this is the only place in the web where they can find other buyers for their stock of UCCMs.

[Bad_Driver]

My arguments with the chinese seller were not successful.
I desoldered the FURUNO board and it's shielding (nightmare!).
Attached HiRes Photos. As you can see one of the resistors is broken. May be this is the reason for the not working receiver.

But it is so incredible small (<< 1 mm) that you can't spot it without any help.
No idea how to fix it 

[PA0PBZ]

Yes, getting the receiver out is a bit of a fight, I know. But that doesn't look broken to me, just not placed very nice. I also think it's a capacitor, not a resistor. It looks like it is still attached though so my bet is that this is not the problem.

[wkb]

yes, I agree. Does not look broken, just a bit awkwardly mounted

[DM4DS]

Write me a PM for adress if I should resolder it for you

My arguments with the chinese seller were not successful.
I desoldered the FURUNO board and it's shielding (nightmare!).
Attached HiRes Photos. As you can see one of the resistors is broken. May be this is the reason for the not working receiver.

But it is so incredible small (<< 1 mm) that you can't spot it without any help.
No idea how to fix it 

[thinkfat]

If you want to attempt a repair, maybe focus on the RF section. Check the Bias section and the signal path through the SAW filter.

Maybe it's something easy like bias network shorting the antenna to ground? Or the cable is dodgy?