[ntp:questions] PPS versus serial offset

Rob nomail at example.com
Wed Aug 28 09:10:22 UTC 2013


detha <detha at foad.co.za> wrote:
> I have a test setup with a RaspberryPi and a SiRF/gpsd module. All
> working quite well, but one thing bugs me. Looking at the ntpq -p output
> the serial port readings seem to drift away slowly but steadily from the
> PPS, see <http://detha.co.za/ntp/ntpmon.20130828.jpg>.

It is normal.  The offset between serial data and PPS changes all the time.

It is often a bit better when you put the GPS in binary mode instead
of NMEA.



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