[time-nuts] Re: Trimble GSPDO - ISSUE

[Ziggy9]

The status shown looks mostly ok. Reference is GPS, plenty of satellites tracked, signal levels ok, etc. Your antenna alarm is due to the 0ma current - should not be a problem. But… your XDOP values are all 0 which seems suspicious and the status is still ‘OCXO Warmup’ (not 100% on that since I don’t have a Trimble unit, only Samsung and Symmetricom). I would suggest that you eliminate the splitter and connect directly to your antenna, just to eliminate things. Also, the OCXO could be substantially off frequency. If possible, I’d measure the EFC voltage and frequency. The output from DIAGnostic:LOG:READ:ALL? would also be useful. 

You also might want to post to EEVBlog as there is a substantial thread on these UCCM units there at https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/

> On Jul 27, 2021, at 2:54 PM, ordnit via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Hi there,
> thank you for valuable information I get everyday from the list.
> 
> After a very long time I managed to power up a Trimble GPSDO, connected
> to an aexternal antenna.
> 
> UCCM >*IDN?
> TRIMBLE,57964-15,86854165,V3.0.0.11-01
> Datecode: 0814 (pretty old, but still in its teen years)
> 
> Some output from "common commands":
> 
> UCCM >SYSTem:STATus?
> 
> -------------------------------------------------------------------------------
> 57964-15     serial number  86854165     firmware ver  3.0.0.11-01LINK  mode
> -------------------------------------------------------------------------------
> Reference Status __________________________   Reference Outputs _______________
> XX Ref 8KHz 0: [LOS]
> XX Ref 8KHz 1: [LOS]                          TFOM     4            FFOM      1
> XX Ref 8KHz 2: [LOS]                          UCCM A Status[OCXO WARMUP]
> XX Ref 8KHz 3: [LOS]
> >> GPS: [phase:-3.3E-05, settling]
> ACQUISITION ...................................................[GPS 1PPS Valid]
> Tracking: 8 ____   Not Tracking: 3 ________   Time ____________________________
> PRN  El  Az  C/N   PRN  El  Az                GPS      11:44:34     27 Jul 2021
> 32  39 107   46     3  10 226
>  1  28 284   37    16   6 189                ANT DLY  0 ns
> 10  40  51   42    14   8 327                Position ________________________
>  8  79 239   45                              MODE     Hold
> 23   7  49   38
> 21  52 297   43                              LAT      N  43:35:11.819
> 27  55 153   43                              LON      E  13:31:1.250
> 22  32 230   41                              HGT              +225.27 m (MSL)
> 
> 
> ELEV MASK  5 deg
> -------------------------------------------------------------------------------
> 
> UCCM >POSSTATus
> 
> ---------------------------------------------
> 07/27/2021  11:44:57
> ---------------------------------------------
> Position: LAT(N  43:35:11.819) LON(E  13:31:1.250) H(        +225.27 m MSL)
> ---------------------------------------------
> Geometry: PDOP(0.0) HDOP(0.0) VDOP(0.0)
> num of visible sats >  10
> num of sats tracked >  10
>  -------- Receiver Channel State --------
> CH  0 > SateID(03) TrackMode(pos avail) SigValue(36)
> CH  1 > SateID(32) TrackMode(pos avail) SigValue(47)
> CH  2 > SateID(01) TrackMode(pos avail) SigValue(37)
> CH  3 > SateID(16) TrackMode(pos avail) SigValue(34)
> CH  4 > SateID(10) TrackMode(pos avail) SigValue(42)
> CH  5 > SateID(08) TrackMode(pos avail) SigValue(44)
> CH  6 > SateID(14) TrackMode(tracking ) SigValue(20)
> CH  7 > SateID(23) TrackMode(pos avail) SigValue(37)
> CH  8 > SateID(21) TrackMode(pos avail) SigValue(44)
> CH  9 > SateID(27) TrackMode(pos avail) SigValue(43)
> CH  10 > SateID(22) TrackMode(pos avail) SigValue(40)
> CH  11 > SateID(00) TrackMode(tracking ) SigValue( 0)
> ---------------------------------------------
> Rcvr Status(1):
> ---------------------------------------------
> Antenna Voltage:  5000.00mV   , Antenna Current:     0.00mA
> 
> UCCM >status
> 
>               - UCCM Slot STATE-
> 
> 1-1. #Now ACTIVE STATUS ---------------- [OCXO Warm]
> 1-2. #Before ACTIVE STATUS ------------- [Alarm]
> 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 ------------------ [Antenna]
> 3-1. #PLL STATUS ----------------------- [DISABLE]
> 3-2. #Current PLL MODE ----------------- [OFFSET OBSERVATION MODE]
> 
> 
> The issue I'm facing is following: even after a long uptime, I never com to a "fast blinking led" and PLL status "enabled". Monitoring device with LHv6, shows an "operation mode" alternating Locked (few seconds" and "recvery". TFOM is quite always 3 or 4. Power supply is linear, with output voltage 5.6V or 6V. I made many tests but had no luck.
> 
> Sys:stat showa a "phase" value moving from -1.4E-05,settling up to
> -4.3E-06, settling. On an old post I read that it might be caused by the oscillator drifting due to age.
> 
> Any guess? Do I have to throw the unit from the window? For your reference, I have a samsung unit connected to same antenna via a splitter. The GPSDO is performing very well.
> 
> Thank you in advance for help.
> Best regards.
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