[time-nuts] Timing between two GPS PPS outputs.

[David J Taylor]

David,

Thanks for the update. The spikes I'm experiencing coincides with the
time when there are 3 or less visible satellites, as predicted by the
Trimble Planning software.
=================================================

I'm glad that's resolved, Gabs.  I have seen similar spikes on my systems, 
and there's no doubt that an outside antenna with a clear view all round 
gives the best results.  I'm located on the top floor of a two-storey house 
and if I mount patch antennas high up in the work-room they can often get a 
"good enough" view.  I've recently moved Raspberry Pi #1 into an unheated, 
north-facing room, and now the temperature variations are less and slower, 
so NTP shows a much more stable offset.  Raspberry Pi #1 is running a 
"navigation" GPS, and #2 a "timing" GPS, and the temperature variations of 
the in-office #2 are the dominant factor:

  http://www.satsignal.eu/mrtg/performance_ntp-pn.php

PC Pixie on that plot is driven from a GPS 18 LVC (not the newer 18x),and 
that receiver is less sensitive and does need to be outside.  It's lying on 
the sloping roof here.

Cheers,
David
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk