[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


With some help from Hal Murray who knows more of NTP than I do, we have 
worked round this problem as described here:


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 

- 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.

SatSignal software - quality software written to your requirements
Web:  http://www.satsignal.eu
Email:  david-taylor at blueyonder.co.uk 

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