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

[Bob kb8tq]

Hi

The gotcha is that the jitter on the base pps output is high enough in this case that doing a reasonable
check (roll over … ) is not as simple as it should be. Best guess is that uBlox has a bug in their GPS 
side of things. Pretty much par for the course on something this new. 

Bob

> On Feb 16, 2019, at 3:59 PM, Achim Gratz <Stromeko at nexgo.de> wrote:
> 
> 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.
> -- 
> +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+
> 
> Waldorf MIDI Implementation & additional documentation:
> http://Synth.Stromeko.net/Downloads.html#WaldorfDocs
> 
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