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

[wkb]

The module has made it back from testing by Paul PA0PBZ, many thanks for that!!  With the original Symmetricom OCXO it works
fine.

I decided that now that the module has been tested to be OK it was time to ensure I have a proper GPS antenna.

A fellow ham operator had some surplus GPS roof antennas available, plus a really neat inline GPS antenna amplifier.
Both Symmetricom branded.  I put the amplifier inline with the antenna cable to my existing roofmounted GPS antenna.
That really helped, suddenly the UCCM module happily received sats! See the LH screenshot. The 'interesting' signal strength
pattern is due to the fact that the antenna is mounted on the side of a VHF/UHF antenna pole.  But works A-ok as far as I am concerned.
Not having to climb on top of the roof in the autumn rain has me sold on the amp 

The UCCM currently has the Trimble OCXO fitted, which works just as bad as before    Paul PA0PBZ has sent me some ideas on how that might be fixable, next step I'd say..

Wilko

[PA0PBZ]

That pattern is normal Wilko. there are no satellites in that direction. It fooled me first too, but look:



The idea I sent to Wilko was using an opamp to make the Trimble look like a Symmetricon OCXO. He told me that the Trimble was much more sensitive on the EFC input so I guess when you attenuate the control signal (10K resistor) and put it in the correct position {X} resistor he should be able to get it working.

Oh by the way, if the fellow ham has more antennas for sale I could be interested

[PA0PBZ]

So I took the Dremel to the failing OCXO only to find another closed metal box    I'm not sure I want to open this because I guess it will move the 10MHz outside the locking range but still undecided. It's a multilayer PCB (4 layers?) so it's hard to figure out what exactly is going on.

Anyway, here are the pics:

[wkb]

Wow.. quite a bit more electronics than I had imagined.  Really puzzling this 2nd small can..

[DM4DS]

Can someone help me with lady heather?

TRyed 57600 8 n 1 and others but she always telling me : no receiver

Board is the Symmetricom with Furuno.
OCXO is a Bliley . 10Mhz can be activated with the momentary. 1PPS also works.

Tryed 2 RS232 USBs but nothing. hTerm only a lot of whatever.

Any ideas?

[thinkfat]

Tryed 2 RS232 USBs but nothing. hTerm only a lot of whatever.

Any ideas?

Post some of the "whatever". Preferably in form of a hexdump. Where did you connected the serial port adapter? What kind of adapter was it?
 

[wkb]

Did you specify /rxc on the command line?

Wilko

[DM4DS]

hterm receives (57600) in hex only 00 00 00 00 (3968 bytes long) , in ASCII its: <\0>
that look in ascii little strange, sorry its not whatever.

LH with /rxc (i havn´t used before) says: No serial port data seen - press ... for help
started now with:  /20 /br=57600:8:n:1 /rxc, also /20 only . LH displays some things but then says above message

it´s normally not so hard to connect a serial rx/tx
Adapter is a FTDI RS232 3,3V 5V (selected with a jumper)

must there something changed on the board or broken parts known?

edited baud rate - 56000 is wrong , that was aalt i tested. 57600 is correct

[wkb]

The header pins are true RS232 signalling +/- 12V so not 5V levels.

Wilko

[DM4DS]

OH ups

Then i level shift them to my adapter. That could be my problem 
long time ago i´ve seen 12V signals.

Thanks Wilko

[texaspyro]

The header pins are true RS232 signalling +/- 12V so not 5V levels.

That depends upon which header you are using.  The small 5 pin header is 12V.  There are low voltage serial ports on the big 50 pin one.  You want to use the 5 pin header (or is it 4 pin?

[wkb]

The 50wire needs a FPC to header conn board. I assume the
5 pin is used by the OP, and that is true RS232 signalling

Wilko

[DM4DS]

I tryed the 4 pin header but something is wrong.

while nothing worked, also not on my good old rs232 adapter, i´m using with the Yaesu FT847 ham rig, i decided to give my MSO5474 a try. there is only a DC with something like a sawtooth on it. No RS232 decoding at no speeds , levels or whatever.

The 10Mhz and 1 PPS are fine but no serial communication.

I´m clueless. My way to solve it , I ordered another one + a Samsung one which i know is a different but the symmetricons I havn´t found any more. And somewhere I´ve seen screenshots from measurements so there must be a way on the samsng too to display the things. And a second GPSDO / third is never a mistake 

If you have ideas, i´m still open for everything

[DM4DS]

While I have only one antenna atm but ordered a second/third unit for testing, can we use one of these cheap GPS Antennas?

https://ebay.us/CfP6hq

If not, can you please point me to one?

Many Thanks

[thinkfat]

Yes, these will work. Make sure you find one with the correct plug. I think it's MCX in most cases.

[DM4DS]

Thanks for the fast reply.

Think I will buy some adapters from MCX to SMA , for mounting at the front of a case and then use these cheap chinese GPS antennas which use SMA.
Also MCX to BNC or N for the 10Mhz. Mountable at the frontplate.

Hope my second unit arrives in the next week or 2, the RS232 on my first unit isn´t working But I don´t give up.

Thanks agn

[PA0PBZ]

Today I opened the box I found inside the Symmetricom OCXO:



And found the following:





Another metal box of course! I guess this is the crystal and I will leave it alone 

[wkb]

Interesting! Week code 04 1998, or maybe PCB design date? Latter is more plausible.

[DM4DS]

Hello again,

the "new" board arrived and the seriel port is working perfect.
No idea why not on the first one.

And while I can´t look at my first one , hope you can help me.

Code: [Select]

UCCM-P > SYSTEM:STATUS?
-------------------------------------------------------------------------------
090-03861-03   serial number W56091xxxxx   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]                         
                                              TFOM     9             FFOM     3
                                              UCCM-P Status[WAIT FOR GPS]
                                             
>> GPS: [no ref]                             
ACQUISITION .............................................. [ GPS 1PPS Invalid ]
Tracking: 4 ____   Not Tracking: 7 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      00:10:37 [?] 06 JAN 1980
 10  18 315   42    12  21 218                GPS      Invalid: inacc position
 20  22 279   35    13  44 146                ANT DLY  +0.000E+00
 23  28 283   42    14  Not OK                Position ________________________
 24  56 286   36    15  66 208                MODE     Survey:      0% complete
                    17  36  95                         Suspended: poor geometry
                    19  30 121                INIT LAT N  49:XX:XX.952
                    28  32  51                INIT LON E   8:XX:XX.028
                                              INIT HGT           +0.00 m  (MSL)
                                             
                                             
                                             
                                             
ELEV MASK  5 deg                             
-------------------------------------------------------------------------------

Command Complete
UCCM-P >
The ACQUISITION .............................................. [ GPS 1PPS Invalid ] makes me nervous.
the survey doesn´t start , too

Any ideas?
Murphy is living here
The survey starts everytime? Can´t find it again on the long thread - my other runs 24/7 and COM doesn´t work as we know. I sound like a old vinyl

Thanks for ideas

[PA0PBZ]

It looks like your antenna has a poor view of the sky (Survey suspended, poor geometry).
Can you post the output of the posstatus command?

[DM4DS]

Code: [Select]

UCCM-P > POSSTATus
-----------------------------------------------------------------------------
11/28/2020 19:48:32
-----------------------------------------------------------------------------
 Position : LAT(N 49:XX:X.222) LON(E 8:XX:XX.732) H(1XX.10 m MSL)
-----------------------------------------------------------------------------
 Geometry : PDOP(0.0) HDOP(46.1) VDOP(46.1)
-----------------------------------------------------------------------------
 Channel Status
   num of visible sats > 9
   num of sats tracked > 3
   ------ Receiver Channel State ------
     CH 0 >  SateID(25) TrackMode(pos avail) SigValue(31)
     CH 1 >  SateID(31) TrackMode(pos avail) SigValue(33)
     CH 2 >  SateID(32) TrackMode(pos avail) SigValue(37)
     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: 5059 mV,  Antenna Current: 18 mA
-----------------------------------------------------------------------------
Command Complete
UCCM-P >
Survey started but suspended again:

Code: [Select]

Survey:    7.7% complete
Suspended: poor geometry
Antenna is outside but only 240° skyview

GPS 1PPS still invalid.
If I measure the Vref Pin it´s always 4V , should it not move until perfect 10Mhz?
I´m using a Bliley NV47A1282 atm, same with the NVG
That looks like a second problem?

Thanks for your help.
(Think it was easier to build one by myself  )

[thinkfat]

With an outside antenna and almost full sky view there should be many more sattelites being tracked. Either the antenna or the receiver are broken.

PS: did you do a factory reset? Maybe there's stale data lingering around in the receiver.

[DM4DS]

No , no reset done.

Before I search hours , can you tell me how?

[ZigmundRat]

It's the 'SYST:PRES' command. It may help, it may not  

It does look like you have GPS issues. You have good reported antenna voltage and reasonable current, but the signals seem poor. You might check the RF connections to be sure they are all properly seated, or if possible try a different antenna.

[DM4DS]

Thanks for the fast response.

Did it and now let it run over night.

The survey was suspended until now, hope it´s better now....will see 2morow.

will update here