[time-nuts] Z3801A version issues - was Re: Substitute GPS in a Z3801A

Matthew Kaufman matthew at matthew.at
Sun Aug 29 21:40:52 UTC 2010


  I believe I've found a difference between the faulty units and the 
working units... The faulty ones come up as 1/1/1997 when you do 
:SYSTEM:PRESET, the good ones come up as 1/1/1998. Does this difference 
ring any bells for anyone?

Matthew Kaufman

On 6/24/2010 8:41 AM, Matthew Kaufman wrote:
> I now have *two* Z3801A units which misbehave in the following way 
> (which this thread reminded me of):
>
> The GPS status says it acquires quite a few (5-6) satellites with high 
> signal strength... then after a minute or two, for no apparent reason, 
> it loses *all* of them simultaneously but immediately goes back into 
> "acquiring" for the ones it was seeing, and a few seconds later, 
> they're all back. During this time, survey (if in progress) is halted 
> and then restarts and runs for a bit before halting again when it 
> loses everything briefly again. Then, within days, the unit ends up 
> out of lock... if I go check it, I see it doing the same thing, and 
> when the satellites are being received it is in "fine frequency 
> adjust" mode, but so far off the 1pps phase that it really has no hope 
> of re-locking before the next time it drops and then reacquires all 
> the satellites.
>
> This is independent of antenna, location, and 48v power source... one 
> unit apparently has been this way since I got it, the other worked 
> fine for months and then developed this problem.
>
> Without knowing more, I'm thinking it might simply be a bad GPS 
> receiver board, thus the idea of trying to find a replacement, perhaps 
> one that is better at staying acquired, has crossed my mind.
>
> Matthew Kaufman
>
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