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

[SHF]

An antenna must be connected so that the red LEDs go out, 5.0V are fully sufficient full function

[thinkfat]

How do you connect the GPSDO module to the PC? The signals on J5 are already RS232 line level. You can directly connect them to a PC serial port. Don't use a TTL converter, it will not work and likely get destroyed.

[Sparky]

How do you connect the GPSDO module to the PC? The signals on J5 are already RS232 line level. You can directly connect them to a PC serial port. Don't use a TTL converter, it will not work and likely get destroyed.

Hello thinkfat and friends:  I saw the note regarding serial (UART/RS232) interfaces, and being unsure which interface to use with Lady Heather I thought this is a good opportunity to find out!

I have the Symmetricom UCCM board and list below the serial interfaces from two of the connectors:

P1 50pin FPC connector - pin number and name according to here.
pin 2 = UART 4 TX, TTL low voltage, baud rate = 625000?

pin 33 = RS232 RX, baud rate = 57600, 8N1 (in website linked above referred to as UART 2)
pin 34 = RS232 TX, baud rate = 57600, 8N1 (in website linked above referred to as UART 2)

pin 36 = UART 3 RX, TTL low voltage, baud rate = 57600, 8N1
pin 37 = UART 3 TX, TTL low voltage, baud rate = 57600, 8N1

J5 4pin 0.1" through-hole
pin 1 = RX = RS232, baud rate = 57600, 8N1
pin 2 = TX = RS232, baud rate = 57600, 8N1
pin 3 = BT = ?
pin 4 = GD = ground


Basic questions just to clarify:
1) Any errors above? 
2) Is it expected the RS232 interface on pins 33/34 appears is the same as on J5 connector?  (On my board it appears to be so.)
3) Which UART/RS232 to use with Lady Heather?
4) Which UART/RS232 to access the console and enter commands like:
UCCM-P > SYSTem:STATus?


I should plug my board in -- plenty of time for such activity now!

[thinkfat]

Basic questions just to clarify:
1) Any errors above? 
2) Is it expected the RS232 interface on pins 33/34 appears is the same as on J5 connector?  (On my board it appears to be so.)
3) Which UART/RS232 to use with Lady Heather?
4) Which UART/RS232 to access the console and enter commands like:
UCCM-P > SYSTem:STATus?


I should plug my board in -- plenty of time for such activity now!

I think there's no error in the description, seems identical to the information I have.
Pin 33/34 is equivalent to J5. This is the interface to use with Lady Heather. It's also the console interface to enter commands (which is essentially what Lady Heather does).

[Nuno_pt]

An antenna must be connected so that the red LEDs go out, 5.0V are fully sufficient full function

Thanks, so that validates that my antenna is really scrap from the fall, need to buy a new one.

How do you connect the GPSDO module to the PC? The signals on J5 are already RS232 line level. You can directly connect them to a PC serial port. Don't use a TTL converter, it will not work and likely get destroyed.

I know the signal on J5 are RS-232, I connect to the PC with RS-232 cable, the problem that I´m facing it's that nothing happens on this connector, I've the -5.6v on J5 pin2, but once I plug it with dupont cables to the RS-232 cable I can't see anything writing on PuTTy, that's way I suggest that maybe Sipex3232E could be broken or something more strange is happening since when I loop pin 2 & 3 together on the dupont cables it writes on PuTTy, so COM1 is ok, cables are ok too.

Any ideas why I can't seem to see nothing on PuTTy?

 

[thinkfat]

An antenna must be connected so that the red LEDs go out, 5.0V are fully sufficient full function

Thanks, so that validates that my antenna is really scrap from the fall, need to buy a new one.

How do you connect the GPSDO module to the PC? The signals on J5 are already RS232 line level. You can directly connect them to a PC serial port. Don't use a TTL converter, it will not work and likely get destroyed.

I know the signal on J5 are RS-232, I connect to the PC with RS-232 cable, the problem that I´m facing it's that nothing happens on this connector, I've the -5.6v on J5 pin2, but once I plug it with dupont cables to the RS-232 cable I can't see anything writing on PuTTy, that's way I suggest that maybe Sipex3232E could be broken or something more strange is happening since when I loop pin 2 & 3 together on the dupont cables it writes on PuTTy, so COM1 is ok, cables are ok too.

Any ideas why I can't seem to see nothing on PuTTy?

Is your antenna passive or active? If it's a passive antenna, you need to switch off the antenna monitoring of the GPSDO. It detects a power draw from an active antenna and reports a fault if it's not there.

But in order to do that, you need to have a connection with the GPSDO console first.

If you own an oscilloscope, you can monitor the TX line while rebooting the GPSDO. It will output some banner and diagnostic messages that will show up on the scope.

Have you checked the trivial problem of mixing up RX and TX?

[Sparky]

I think there's no error in the description, seems identical to the information I have.
Pin 33/34 is equivalent to J5. This is the interface to use with Lady Heather. It's also the console interface to enter commands (which is essentially what Lady Heather does).

Thank you!   

I powered it up and connected J5 to the COM-USB translator, and this is what I got:

Code: [Select]

UCCM > SYSTEM:STATUS?
-------------------------------------------------------------------------------
090-03861-13   serial number S3ZBC20150   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: 2 ________   Time ____________________________
                   PRN  El  Az                GPS      00:11:38 [?] 06 JAN 1980
                    16  61  12                GPS      Invalid: not tracking
                    26  47  64                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                             
-------------------------------------------------------------------------------

Command Complete

I have a terrible sky view, so I'm just going to wait a lot and hope this improves!


In the meantime I played around with some of the commands from the first post:

Code: [Select]

UCCM >  *IDN?
Symmetricom,090-03861-13,S3ZBC20150,1.0.0.5-01
Command Complete

Code: [Select]

UCCM >  STATus

                 - UCCM-LP Slot STATE -



1-1. #Now UCCM-LP STATUS --------------- [Master Manual]
1-2. #Before UCCM-LP STATUS ------------ [Wait for GPS]
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

Code: [Select]

UCCM > POSSTATus
-----------------------------------------------------------------------------
1/6/1980 00:32:02
-----------------------------------------------------------------------------
 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 > 9
   num of sats tracked > 1
   ------ Receiver Channel State ------
     CH 0 >  SateID(20) TrackMode(pos avail) 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: 5147 mV,  Antenna Current: 8 mA
-----------------------------------------------------------------------------
Command Complete

The "ACT" LED was originally flashing GREEN, but now (when I logged the above messages) it is solid GREEN and flashing RED.

So I think it is waiting to make another attempt and track more satellites.

[Nuno_pt]

Is your antenna passive or active? If it's a passive antenna, you need to switch off the antenna monitoring of the GPSDO. It detects a power draw from an active antenna and reports a fault if it's not there.

But in order to do that, you need to have a connection with the GPSDO console first.

If you own an oscilloscope, you can monitor the TX line while rebooting the GPSDO. It will output some banner and diagnostic messages that will show up on the scope.

Have you checked the trivial problem of mixing up RX and TX?

When I buy the antenna was a active one, but after the fall it can be broken, so not sure about the condition of the antenna.

I don't own a scope yet (trying to decide between Siglent 12xx and Rigol 11xx), but I can measure the voltages on the Sipex 3232E if this help.
What is making scratch my head is why i can't communicate with GPSDO console.

I've change the pins 2&3 connection to see if that change anything, but with the same results.

From what I can see the buttons MACT & RESET doesn't have any effect on the led's when press.

[thinkfat]

I don't own a scope yet (trying to decide between Siglent 12xx and Rigol 11xx), but I can measure the voltages on the Sipex 3232E if this help.
What is making scratch my head is why i can't communicate with GPSDO console.

I've change the pins 2&3 connection to see if that change anything, but with the same results.

From what I can see the buttons MACT & RESET doesn't have any effect on the led's when press.

Pressing the RESET button should have an effect on the LEDs, they should go off and back on again. That's concerning.
If you put a DMM on the TX pin of J5, you should see the read-out changing for a while after you press the RESET button (or after a power cycle)

If nothing of the above happens, most likely you have a faulty unit.

[thinkfat]

I think there's no error in the description, seems identical to the information I have.
Pin 33/34 is equivalent to J5. This is the interface to use with Lady Heather. It's also the console interface to enter commands (which is essentially what Lady Heather does).

Thank you!   

I powered it up and connected J5 to the COM-USB translator, and this is what I got:

Code: [Select]

UCCM > SYSTEM:STATUS?
-------------------------------------------------------------------------------
090-03861-13   serial number S3ZBC20150   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: 2 ________   Time ____________________________
                   PRN  El  Az                GPS      00:11:38 [?] 06 JAN 1980
                    16  61  12                GPS      Invalid: not tracking
                    26  47  64                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                             
-------------------------------------------------------------------------------

Command Complete

I have a terrible sky view, so I'm just going to wait a lot and hope this improves!


In the meantime I played around with some of the commands from the first post:

Code: [Select]

UCCM >  *IDN?
Symmetricom,090-03861-13,S3ZBC20150,1.0.0.5-01
Command Complete

Code: [Select]

UCCM >  STATus

                 - UCCM-LP Slot STATE -



1-1. #Now UCCM-LP STATUS --------------- [Master Manual]
1-2. #Before UCCM-LP STATUS ------------ [Wait for GPS]
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

Code: [Select]

UCCM > POSSTATus
-----------------------------------------------------------------------------
1/6/1980 00:32:02
-----------------------------------------------------------------------------
 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 > 9
   num of sats tracked > 1
   ------ Receiver Channel State ------
     CH 0 >  SateID(20) TrackMode(pos avail) 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: 5147 mV,  Antenna Current: 8 mA
-----------------------------------------------------------------------------
Command Complete

The "ACT" LED was originally flashing GREEN, but now (when I logged the above messages) it is solid GREEN and flashing RED.

So I think it is waiting to make another attempt and track more satellites.

That looks like you have really no sky view at all. What makes me wonder, though, is that the receiver claims to know how many satellites are visible. For that, it must at least have a rough idea of its position and it must have been able to receive at least almanac data from the satellites. There's a chance that there is stale data stored somewhere. I suggest you do a factory-reset of the device and try again. It might be looking for all the wrong satellites.

[Nuno_pt]

Pressing the RESET button should have an effect on the LEDs, they should go off and back on again. That's concerning.

Yep that's not happening, led's still red, MACT & RESET buttons are working since they cut the voltage when press, so something could be holding the reset state.

If you put a DMM on the TX pin of J5, you should see the read-out changing for a while after you press the RESET button (or after a power cycle)

On J5-2 when RESET button is press, nothing happens, steady at -5.6v, but when power off, the voltage dips to -1.4xx, and to -5.6v when power on steady, it seems is stuck.

Did some more measurements with the unit power on:

Continuity test, J5-2 it's tied to C366, C364, C367, and to Maxim3232cwe pins 1,2,3,4,5,7,9,10,11,12,14,15,16
On C366 on one side I've 5.947v on the other side 0.0118v
On C367 on one side I've 5.605v on the other side 0.0001v
On C364 on one side I've 5.958v on the other side 3.279v

Seems that something is happening with Maxim

In attach there are the voltages of my Maxim3232cwe, I could try and plug pins 9 & 12 to a TTL --> RS-232 board with a Max3232, and see if there are some communication, what do you think?

If nothing of the above happens, most likely you have a faulty unit.

Let's see if I need to buy some new units.

[Sparky]

That looks like you have really no sky view at all. What makes me wonder, though, is that the receiver claims to know how many satellites are visible. For that, it must at least have a rough idea of its position and it must have been able to receive at least almanac data from the satellites. There's a chance that there is stale data stored somewhere. I suggest you do a factory-reset of the device and try again. It might be looking for all the wrong satellites.

Yes, I do have really terrible sky view.  Imagine the 3rd floor window of an apartment building in a city district...

I moved the antenna and try again this morning.  To my surprise it was able to pick up a number of satellites and at one stage was tracking 5 of them:

Code: [Select]

ACQUISITION .............................................. [ GPS 1PPS Invalid ]
Tracking: 2 ____   Not Tracking: 8 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      18:23:16     04 APR 2020
  9  30 156   36     5  19 271                GPS      Assessing stability
 13  22 316   29     7  61  60                ANT DLY  +0.000E+00
                     8  30  52                Position ________________________
                    11  20  90                MODE     Survey:    5.5% complete
                    17  11 183                         Suspended: track <4 sats
                    27   5  33                AVG LAT  N  37:46:xx.yyy
                    28  55 242                AVG LON  W 122:24:xx.yyy
                    30  65 334                AVG HGT           +34.61 m  (MSL)                                             

At least it figured out what the time is...and started the survey!     Hopefully it will resume after sometime and gradually complete!

[Sparky]

I'm surprised how difficult it is to find a RS232-level (not TTL-level!) to USB breakout board.  All the FTDI-based boards I've seen from Adafruit/Sparkfun convert TTL-level (3.3V or 5V) to USB, and do not seem compatible with RS232 levels.

Does anyone know of a breakout board that integrates MAX3232 for RS232 to TTL level translation, and then follows with USB conversion?

[Sparky]

The survey completed and it switched to HOLD mode:   

Code: [Select]

ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 5 ____   Not Tracking: 5 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      21:02:14     04 APR 2020
  7   6 132   32     1  17  48                GPS      Synchronized to UTC
 13  44 233   34     6  11 165                ANT DLY  +0.000E+00
 19  64 201   37    15  31 271                Position ________________________
 24  15 313   35    17  83  91                MODE     Hold
 30  38 130   35    28  53  45               
                                              LAT      N  37:46:xx.yyy
                                              LON      W 122:24:xx.yyy
                                              HGT               +20.20 m  (MSL)

The status command gives following output:

Code: [Select]

UCCM > status
                 - UCCM-LP Slot STATE -

1-1. #Now UCCM-LP STATUS --------------- [Master]
1-2. #Before UCCM-LP 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]
     #ALARM STATUS
     #H/W FAIL ---------- [ EXT ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [NORMAL 2 MODE]

What is the meaning of #H/W FAIL ---------- [ EXT ]?

[bingo600]

I'm surprised how difficult it is to find a RS232-level (not TTL-level!) to USB breakout board.  All the FTDI-based boards I've seen from Adafruit/Sparkfun convert TTL-level (3.3V or 5V) to USB, and do not seem compatible with RS232 levels.

Does anyone know of a breakout board that integrates MAX3232 for RS232 to TTL level translation, and then follows with USB conversion?

I'd prob go for a Genuine FTDI cable , and a matching db9 from your board , have used the US232R-100 for years
https://www.digikey.dk/product-detail/da/ftdi-future-technology-devices-international-ltd/US232R-100-BULK/768-1074-ND/2441363

The FTDI boards on most "Sites" are FAKE , and it's even worse with the max232/3232 boards.

If you need a Breakout board , i'd recommend CP2102/CP2104 , no probs on Win/Linux. I havent seen fakes ... Well drivers destroying those.
Then get original max232/3232 and make your own adapter.

A quick way to make a functional max232 board , is to buy a few fakes , and replace the chip w. an original max232 (digikey/mouser etc...)

/Bingo

[thinkfat]

The survey completed and it switched to HOLD mode:   

Code: [Select]

ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 5 ____   Not Tracking: 5 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      21:02:14     04 APR 2020
  7   6 132   32     1  17  48                GPS      Synchronized to UTC
 13  44 233   34     6  11 165                ANT DLY  +0.000E+00
 19  64 201   37    15  31 271                Position ________________________
 24  15 313   35    17  83  91                MODE     Hold
 30  38 130   35    28  53  45               
                                              LAT      N  37:46:xx.yyy
                                              LON      W 122:24:xx.yyy
                                              HGT               +20.20 m  (MSL)

The status command gives following output:

Code: [Select]

UCCM > status
                 - UCCM-LP Slot STATE -

1-1. #Now UCCM-LP STATUS --------------- [Master]
1-2. #Before UCCM-LP 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]
     #ALARM STATUS
     #H/W FAIL ---------- [ EXT ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [NORMAL 2 MODE]

What is the meaning of #H/W FAIL ---------- [ EXT ]?

Looks good! 

The H/W fail means it's missing its external reference signal. That probably means this unit was slaved to an external 1PPS while in operation, instead of using its own GPS. It's now using its own GPS in what seems to be a fallback mechanism. That should be no problem.

[Sparky]

If you need a Breakout board , i'd recommend CP2102/CP2104 , no probs on Win/Linux. I havent seen fakes ... Well drivers destroying those.
Then get original max232/3232 and make your own adapter.

A quick way to make a functional max232 board , is to buy a few fakes , and replace the chip w. an original max232 (digikey/mouser etc...)

/Bingo

Thanks, Bingo!  Yes, I'm actually using one of those genuine FTDI cables at the moment, wiring the DB9 pins directly to the J5 connector.  It does work well but I'd prefer a simple USB cable to connect the GPSDO to my computer. 

I actually have CP2104 breakout from Adafruit (https://www.adafruit.com/product/3309) so I'll just get a legit MAX3232 to interface with the GPSDO.

Thanks for your note -- it helped confirm what I need to do!

Best,
Sparky

[Sparky]

Looks good! 

The H/W fail means it's missing its external reference signal. That probably means this unit was slaved to an external 1PPS while in operation, instead of using its own GPS. It's now using its own GPS in what seems to be a fallback mechanism. That should be no problem.

Thanks thinkfat!  It's reassuring to have your explanation that the "fail" message is not going to be a problem.

Now that everything is working well, I can move on with design the enclosure, proper mounting board, etc.

[bingo600]

so I'll just get a legit MAX3232 to interface with the GPSDO.
Sparky

You could do with a MAX232 , as you have the 5v for it (from USB) , but if you have 3v3 on the Ada USB board , 3232 would do too
The MAX232A or is it N , just need 100nF caps instead of 1uF on the original vers.  .. Worth thinking about

[BFX]

Hmmm Corona forced me to get to my GPSDO 

What experience do you have guys with those cheep Chinese GPS antenas? because my is really bad


RS232 messed up


Finally few satelites


Good sign


Even better sign:)


Happy Agilent

Next step is the power supply , case and nice VFD display for that GPSDO guy

[thinkfat]

I've had one GPS antenna (puck style) DOA, another two were fine and giving good results.

[Cat]

What does A/S change mean?
The log gets spammed with these messages:

Code: [Select]

L333:1980-01-06 00:09:57:A/S change: Slave(HIGH)
L334:1980-01-06 00:09:59:A/S change: Master(LOW)
L335:1980-01-06 00:10:01:A/S change: Slave(HIGH)
L336:1980-01-06 00:10:05:A/S change: Master(LOW)It seems like pin 8 is a high impedance input and responsible for the messages. When measuring with a DMM it gets pulled down to 0,3 V and in the log appears A/S change: Master(LOW)
When disconnecting the A/S change: Slave(HIGH) entry is logged.
Everything else seems normal.
The GPSDO is a Symmetricom 090-03861-13 serial number S3ZD320xxx firmware ver 1.0.0.5-01

[MindBender]

What experience do you have guys with those cheep Chinese GPS antenas? because my is really bad

Please note that timing specialised GPS receivers, are whole different receivers than positioning specialised receivers. Therefore, they also have different requirements for their antennae.

Years ago, I worked as a freelance software engineer for a well-known brand of first portable and later in-car navigation devices devices. For trouble-shooting problems we had with the SiRF GPS receivers we were using, I got to speak to some of the engineers at SiRF. And due to my life-long fascination for precision time keeping, we also talked about timing receivers (If you are interested in precision time keeping, I can highly recommend the Time Nuts mailing list http://www.leapsecond.com/time-nuts.htm).

Anyway, what I took away from the conversations we had was:
1. Specialised timing GPS receivers use specialised firmware. This firmware strives for a low TDOP. This automatically means a high HDOP (and VDOP and PDOP)
2. For a low TDOP, the SVs tracked must be as close together as possible, as high in the sky as possible. (a low HDOP requires SVs in a constellation as far apart as possible).
3. For maximum timing accuracy, a helical antenna must be used. If I remember correctly, for steeper rise/fall times on the received signal; The signal 'bounces' around in the ceramic patch, making it fuzzier.
4. Trimble owns all the patents for timing specialised GPS receivers, hence they make the best ones.

At that time, one of the very best timing specialised GPS receiver was the Trimble Resolution-T. Its 1PPS output is within 14ns of UTC and it is cheap. Use this to discipline a good Rubidium standard with 1PPS input, such as the SRS PRS10, and you've got the most accurate frequency standards and reference clocks you ca build yourself.

Gee; That went off-topic real quickly. I'm posting anyway, because I hope this information is useful to anybody following this thread. If not, feel free to delete it, admin.

[bingo600]

Just got one of these : Samsung STP2945LF 10MHz GPS Disciplined Clock GPSDO

46 pages is a lot ....
Is the TTL levels on the FPC cable 5v TTL or 3.3v ?

Does anyone have a manual ?

TIA
/Bingo

[DEPChimp]

Found this for STP2945LF on Twitter from @Rasiel_J https://twitter.com/Rasiel_J/status/1137661271115911168
Had some fun hand writing the hanzi characters in www.qhanzi.com, to translate this is what I come up with.
Edit: Corrected my link