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

Chris Albertson albertson.chris at gmail.com
Tue Jul 12 17:24:35 UTC 2011


On Tue, Jul 12, 2011 at 10:16 AM, Mike S <mikes at flatsurface.com> wrote:
> At 08:01 AM 7/12/2011, Michael Eder wrote...

> Try adding "tos mindist 0.015" to your ntp.conf. This widens the correctness
> interval used by the clock selection algorithm. Basically, it accommodates
> the jitter in the serial NMEA stream. 0.01 is another commonly used value,
> but you may want more or less. It should be as small as possible while
> providing reliable operation.
>
> From the docs ( http://www.cis.udel.edu/~mills/ntp/html/prefer.html ):
> "the prefer peer can still be discarded by the intersection algorithm as a
> falseticker. To avoid this, it is usually wise to increase the mindist
> option of the tos command from the default .005 s to something like .05 s."


The above is technically correct but if you find that Internet pool
servers are seriously out performing your GPS, then maybe you need a
better GPS.


Chris Albertson
Redondo Beach, California



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