[ntp:questions] A Christmas puzzler - intermittent offset oscillations with a PPS source

David Taylor david-taylor at blueyonder.co.uk.invalid
Mon Jan 7 11:14:12 UTC 2013

On 21/12/2012 09:55, David Taylor wrote:
> I have two Raspberry Pi card computers both synced to GPS/PPS sources.
> #1 is using a u-blox 6M "navigation" GPS, and #2 a Trimble resolution
> SMT "timing" GPS.  Every now and then (perhaps one day on ten?), the
> "navigation" synced device develops spikes in the offset of about 8
> microseconds in duration, as shown here:
> Graphs for December 20:
>    http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html#oscillations
> Current data:
>    http://www.satsignal.eu/mrtg/performance_ntp-pn.php

Update: these oscillations appear to have been cured by a firmware 
update on Raspberry Pi #1, from version 337601 to version 346337.  The 
graphs will take a time to update, reaching primary stability within an 
hour or two.  I will continue watching for any subsequent occurrence of 
this problem.
Web: http://www.satsignal.eu

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