[ntp:questions] Single GPS/PPS time source gets marked as a falseticker

Rob nomail at example.com
Thu Jul 14 08:13:26 UTC 2011

Michael Eder <meder at whoi.edu> wrote:
> We have looked at our GPS on a scope, the PPS it is dead on and the NMEA
> (just one sentence) is also reliable with about a 680 ms latency and 10 ms
> jitter.

Again, are you using gpsd?

If so, you may want to try removing the (huge) 680ms offset inside gpsd
instead of in ntpd.
There is a place in the code where a fixed offset is added to time obtained
using NMEA (because the gpsd author does not want configurable items) and
it cannot be correct for every possible receiver.

Again, it is better to switch from NMEA to the native binary protocol
of the receiver.

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