[time-nuts] Substitute GPS in a Z3801A

bg at lysator.liu.se bg at lysator.liu.se
Thu Jun 24 14:57:36 UTC 2010

Hi Mike,

> At 10:48 PM 6/23/2010, Robert Benward wrote...
>>Has anyone ever put another GPS in a Z3801A?  Will the software
>>another GPS that tracks say, 12 channels?
> Possibly 8 channels. You must use a Motorola Oncore VP. A 6 channel one
> was what HP used. There are mixed reports on using an 8 channel VP -
> some say it works fine, others say you must configure it in 6 channel
> mode (but you do pick up improved reception). Whether the different
> reports are due to changes in configuration or firmware of the z3801a,
> the Oncore, or both - I have no idea.
> The commands/responses used by the z3801a prevent it from working
> directly with newer GPS modules, like the GTs, UTs or M12s (even if you
> adapted them physically).
> If you want to try and get better performance with a newer GPS
> receiver, you should be able to leave the existing board in place, and
> bypass the 1PPS input with the signal from the newer receiver. You'd
> only get in trouble in exceptional conditions (new receiver loses sync,
> but existing one is reporting good satellite lock, etc.). Of course,
> the z3801a satellite reporting wouldn't be worth much.

Is it established that the Z3801 does not use sawtooth corrections for the
1PPS pulses it receives from the oncore VP?

IF it use these corrections even a substitute "perfect" 1PPS will be worse
than the orginal setup.



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