[time-nuts] My Garmin 18x, Ver 3.50, currently 1 second slow to UTC
David J Taylor
david-taylor at blueyonder.co.uk
Thu Jan 13 07:50:51 UTC 2011
> This agrees with what Kasper Pedersen wrote earlier:
>> 3.10 starts transmitting 350ms .. 480ms after PPS
>> 3.30 starts transmitting 920ms .. 1220ms (!) after PPS
>> 3.50 starts transmitting 700ms .. 1220ms (!) after PPS
Folks,
With some help from Hal Murray who knows more of NTP than I do, we have
worked round this problem as described here:
http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm#gps-18x
The basic steps were:
- make the GPX18x LVC "noselect" so that NTP would not use it
- enable the peerstats to measure where NTP thought the 18x end of message
occurred
- analyse the peerstats file to determine the apparent offset (which
was -1.000 seconds, as it happened)
- add that offset (as +1.000 seconds) to the fudge time2 value for the 18x
in the ntp.conf
- restart NTP
I hope that helps someone.
Cheers,
David
--
SatSignal software - quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk
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