[time-nuts] Z3805A GPS module going deaf, what modules can replace it?
Mike Cook
michael.cook at sfr.fr
Fri Feb 13 21:05:21 UTC 2015
The model number is that of an Oncore VP. It is easy to remove the receiver from the unit for testing independently. That might be worth a try. Maybe reseating it may help if there is any continuity problem on the pins. Unfortunately you will probably need another VP to replace a dead one. IIRC, I did try to replace a VP in my Z3801A with a UT+ , but it would not work.
"Ceux qui sont prêts à abandonner une liberté essentielle pour obtenir une petite et provisoire sécurité, ne méritent ni liberté ni sécurité."
Benjimin Franklin
> Le 13 févr. 2015 à 20:28, John Stone <johns at ks.uiuc.edu> a écrit :
>
> Hi,
> I've got a Z3805A that I bought off ebay a couple of
> years ago, and it recently started going deaf, beginning
> with an apparent loss of sensitivity leading to holdovers,
> and more recently, receiver errors reported in the system
> status.
>
> I have the Z3805A, a thunderbolt, and one of the recently discussed
> KS-24361 units sharing the same GPS antenna via a four output
> 58536A distribution box. I've run the Z3805A on its own
> separate antenna and compared its signal levels with the
> other units, and it has clearly developed some issue.
> After a power cycle, I can get it going by initiating a
> survey, but after a day or two of running it will lose
> all sats, and in some cases the status command will show
> "GPS Rcv: Err".
>
> I queried the hardware info on the GPS in this unit and
> from what I've gathered, it's one of the earliest motorola
> Oncore GPS receivers based on the "B1121P1114" model number.
> What GPS module models can I put into a Z3805A to get it
> running again? Any tips are appreciated, including suggestions
> for tests I could run on the GPS module, the power supply, or
> other items that might be common failure points.
>
> I've included the output from scpi queries below, and the
> status from the KS-24361 attached to the same antenna
> for comparison:
>
> *IDN?
> HEWLETT-PACKARD,Z3805A,3542A00943,3543B-A
>
> :DIAG:LIF:COUN?
> +29437
>
> :DIAG:IDEN:GPS?
> "COPYRIGHT 1991-1995 MOTOROLA INC.",
> "SFTW P/N # 98-P39972M ",
> "SOFTWARE VER # 8 ",
> "SOFTWARE REV # 4 ",
> "SOFTWARE DATE 13 JUL 1995",
> "MODEL # B1121P1114 ",
> "HDWR P/N # _ ",
> "SERIAL # SSG0120281 ",
> "MANUFACTUR DATE 5M18 ",
> "OPTIONS LIST IB "
>
>
> Failing Z3805A system status output:
> ------------------------------- Receiver Status -------------------------------
>
> SYNCHRONIZATION ........................................... [ Outputs Invalid ]
> SmartClock Mode ___________________________ Reference Outputs _______________
> Locked to TFOM 9 FFOM 3
> Recovery 1PPS TI --
> Holdover HOLD THR 1.000 us
>>> Power-up: GPS acquisition Holdover Uncertainty ____________
> Predict --
>
> ACQUISITION .......................................... [ GPS 1PPS CLK Invalid ]
> Satellite Status __________________________ Time ____________________________
> Tracking: 0 Not Tracking: 0 GPS 08:51:14 [?] 12 Feb 2015
> 1PPS CLK Absent or freq error
> ANT DLY 180 ns
> Position ________________________
> MODE Survey: 0% complete
> Suspended: no track data
> INIT LAT N 40:08:01.714
> INIT LON W 88:12:27.166
> ELEV MASK 10 deg INIT HGT +198.59 m (MSL)
> HEALTH MONITOR ...................................................... [ ERROR ]
> Self Test: OK Int Pwr: OK Oven Pwr: OK OCXO: OK EFC: OK GPS Rcv: Err
> scpi >
>
>
> For comparison, here is what my recently acquired Z381x / KS-24361 GPSDO
> says, driven from the same antenna:
>
> -------------------------- Secondary Receiver Status --------------------------
> SYNCHRONIZATION ............................................. [ Outputs Valid ]
> SmartClock Mode ___________________________ Reference Outputs _______________
>>> Locked to GPS TFOM 3 FFOM 0
> Recovery 1PPS TI +10.0 ns relative to GPS
> Holdover HOLD THR 1.000 us
> Power-up Holdover Uncertainty ____________
> Predict 3.7 us/initial 24 hrs
>
> ACQUISITION ................................................ [ GPS 1PPS Valid ]
> Tracking: 8 ____ Not Tracking: 2 ________ Time _____ +1 leap second pending
> PRN El Az C/N PRN El Az GPS 19:22:10 13 Feb 2015
> 1 23 302 37 11 15 278 GPS 1PPS Synchronized to GPS Time
> 4 32 269 43 18 18 138 ANT DLY 60 ns
> 12 20 49 38 Position ________________________
> 14 66 30 46 MODE Hold
> 22 53 146 39
> 25 36 90 38 LAT N 40:08:00.925
> 31 61 216 42 LON W 88:12:26.995
> 32 43 310 46 HGT +200.94 m (GPS)
> ELEV MASK 10 deg
> HEALTH MONITOR ......................................................... [ OK ]
> Self Test: OK Int Pwr: OK Oven Pwr: OK OCXO: OK EFC: OK GPS Rcv: OK
>
>
> Cheers,
> John Stone
>
> --
> NIH Center for Macromolecular Modeling and Bioinformatics
> Beckman Institute for Advanced Science and Technology
> University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
> http://www.ks.uiuc.edu/~johns/ Phone: 217-244-3349
> http://www.ks.uiuc.edu/Research/vmd/
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