[time-nuts] week 1024 roll over

Roy Phillips phill.r1 at btinternet.com
Fri Apr 18 04:32:11 EDT 2008

Interesting to hear your problems with the Datum - I have the same problem 
with an Odetics 325 - my date is the same , currently Sept 02,1988, but I am 
pleased to tell you that it has no effect on the performance of the 
equipment. I have the correct time and a GDOP of 1.8 and  TFOM=4 . I did 
have to replace the lithium battery in the Receiver section (it had 0 
volts!) and now the system can store its essential data and re-start with 
little delay. I would like to find a firmware correction to this problem, 
but as I have been informed - "the date was never a priority with GPS" ! ? 
Its nice to have this facility as well as the Rubidium Standard - they are 
now in step, and checked every day.

Good luck

Roy P

----- Original Message ----- 
From: "Glenn Little WB4UIV" <glennmaillist at bellsouth.net>
To: "Time-Nuts list" <time-nuts at febo.com>
Sent: Friday, April 18, 2008 6:19 AM
Subject: [time-nuts] week 1024 roll over

>I recently bought a Datum GPS Time/frequency System 9390-5593. When I
> enter date, time and location, it fails to indicate GPS lock. It is
> indicating GPS week 451, when the week is really 1475. It is also
> indicating that the day is 246. I highly suspect that the receiver
> has firmware that needs to be updated.
> I have not disassembled the equipment far enough to verify the type
> of GPS engine installed. Does anyone know what GPS engine is
> installed in this equipment?
> Will the 1024 week rollover cause the receiver not to lock, I suspect
> that the receiver will not lock as it has incorrect date?
> Can I change the engine to something that has correct firmware?
> Does the receiver output NMEA 0183 data or something unique?
> I contacted Symmetricom as they bought Datum. They say this product
> was out of support prior to them buying Datum. I requested the price
> of a manual. They will sell me one, if they have one to copy, for a
> mere $250.00. I suspect that they do not have a firmware update that
> they will release for a reasonable cost. This is a hobby, not a
> business for me.
> Any help or advice? Possibly just scrap this and use the Rb standard?
> Thanks
> 73
> Glenn
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