[time-nuts] week 1024 roll over

Rob Kimberley rk at timing-consultants.com
Fri Apr 18 11:57:08 EDT 2008

Hi Glenn

I'm pretty certain I have a manual for this (will check and get back to
you). However, Symmetricom are right about the firmware, this unit was prior
the Datum takeover, and they don't have the information available now. If
the unit is tracking, then the time should be right, but date wrong. It only
affects the date, and should not have any affect on its ability on frequency
outputs and disciplining the Rubidium. The engine used would have been a
Trimble one, but without checking the manual, I can't tell you which. Other
time nuts have reported this problem, and it may be worth checking the

Rob Kimberley 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Glenn Little WB4UIV
Sent: 18 April 2008 06:20
To: Time-Nuts list
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
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
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?


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