[time-nuts] Accuracy/drift of Garmin GPS 16 HVS 1 PPS output under invalid fix conditions...

[Steve Olney]

Hi Bob,

On 13/03/2019 1:30 am, Bob kb8tq wrote:
> Sorry if this is an ongoing / somewhat random dump of a bunch of things … I am not doing the
> same sort of thing you are doing. That makes a lot of this a bit less focused than maybe
> it could be.

Thanks for your suggestions - they have been most helpful.  It was just 
when the discussion turned to Maser clocks and interferometry that I was 
concerned that the discussion had "dropped out of lock and drifting with 
many ppm" :-)

I simply want to know about the behaviour of the GPS 16 HVS under 
no-lock conditions.   I need that information to optimise a fail-safe 
mechanism in my software.  Basically, if there is a loss of lock I need 
to account for that.   In my application, it doesn't matter if the GPS 
unit drops out of lock as I can re-schedule the timing event to a 
slightly later time when a valid fix is present.  All that matters is 
that I have an accurate time-stamp.  It doesn't matter if that 
time-stamp is re-scheduled for a minute or two later.   However, if I 
know the drift of the 1 PPS output under invalid fix conditions I might 
not need to reschedule the timing event at all as long as the 
(tdrift/dt) * (how long the invalid fix has lasted) < 1 ms.  The value 
of tdrift/dt is the key to implementing this.

Thanks for your suggestions.

Cheers

Steve

HawkRAO