[time-nuts] TruePosition GPSDO Holdover Issues

Bob kb8tq kb8tq at n1k.org
Sun May 13 11:08:08 EDT 2018


Hi

Assuming the device has the “normal stuff” in it, it will look at the location in memory and
compare that to the current solution. If the solution is off by more than the limit, it will
reject it. If it rejects enough data ( = no good solution) it goes into holdover. Some devices
will operate down to a single satellite against a memorized position. That is not true of all
gizmos. Even with the “single sat” devices, there is a multi sat / bad location solution situation 
that will send you into holdover. 

Bottom line is that it usually is antenna location. Clear view of the sky and an appropriate 
elevation mask are what you are after.

Bob

> On May 13, 2018, at 10:27 AM, gandalfg8--- via time-nuts <time-nuts at febo.com> wrote:
> 
> Ok, I give up....
> 
> I've been logging this with Lady H and was watching again this afternoon as the sat count dropped but this time there was no dropping into holdover as the number of sats dropped from four to three....damn, it just carried on doing its thing until the count went up again:-)
> 
> I'm still seeing the occasional reported random holdover event but am still no nearer to knowing why.
> 
> Otherwise it's a nice unit and does handle the holdover well, even a longer event yesterday whilst there was a supposed antenna fault didn't reflect into the frequency plots, but time to call a halt for now.
> 
> Nigel, GM8PZR
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