[ntp:questions] Spike detection and clock runaway

Dave Hart hart at ntp.org
Thu Feb 23 23:01:10 UTC 2012

On Thu, Feb 23, 2012 at 22:45, A C <agcarver+ntp at acarver.net> wrote:
> I will have to process and plot my peerstats and loopstats files but the
> graph does seem to line up with approximately what I see on my system. The
> difference in my case is that I'm using ATOM as the refclock (instead of
> NME) and Internet servers as my other sources (gpsd is still not involved
> here, it's in the config as noselect).

The 2143 fix affects only the NMEA driver #20, but if it symptoms look
similar to what you're seeing, the underlying cause may be the same.
If switching to using NMEA temporarily for testing fixes it, you would
know your PPS is not so trustworthy when the NMEA sentence indicates
less than acceptable reception.  That sort of the obvious win in using
the nmea driver's integrated PPS support -- you're not artificially
disconnecting the GPS PPS signal from its NMEA context.

Dave Hart

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