[time-nuts] Correcting measured PPS values with receiver sawtooth correction values

[Achim Gratz]

Mark Sims writes:
> For all the receivers that I have tested there is only one combination
> that jumps out as being the correct one.  However, for the new Ublox
> F9P, there are two combinations that produce virtually identical
> measurements and statistics (add current sawtooth or subtract previous
> sawtooth).  Any ideas on how to determine which combination is the
> "correct" one?

I don't think that uBlox changed the defaults over their previous
generation, so whatever worked for the M8 series should be applicable
here.  If you're using the UBX-TIM-TP message data, this always applies
to the TIMEPULSE0 output following the message.  The message and the
measurement rate as well as the PPS frequency need to match up for this
to work as expected.

Now, if you want to check, I think you need to wait for a clear
wraparound to appear in the sawtooth correction, which should coincide
with a cycle slip on the next PPS pulse (not the previous one).


Regards,
Achim.
-- 
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