[time-nuts] Four hour cycle in GPS NMEA jitter
geoff36 at gmail.com
Tue Mar 21 19:24:16 EDT 2017
> Why would a GPS module produce jitter with a pattern like this?
Trent, I must admit I have not seen such a four hour "spike" before in
the NMEA latency, however a clue may be that the GPS ephemeris
(broadcast by the SV's) orbit description is valid only for a "4 Hour
Period" - before the SUN and Moon and other factors make it too
I did a Google search for
telit ephemeris gps "4 hour"
and found that the TELIT appears to have some algorithm that enhances
somehow the ephemeris. Maybe your 4 hour spike (which appears to be
for 4 seconds each time) is evidence of your TELIT doing some extra
homework involving the ephemeris - just a guess on my part.
Regards, Geoff (Christchurch , New Zealand)
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