[ntp:questions] how to have offset < 1ms

David Lord snews at lordynet.org
Mon Apr 12 22:44:18 UTC 2010

lhommedumatch wrote:
> I'm working on a oceanographic vessel
> ntpgmtaceb is our reference clock that is synchronised with a gps at
> the beginning of a cruise.
> The drift of this clock is <1ms each day.
> It's connected on the lan board of our vessel.
> I have removed these two lines
> server
> fudge stratum 10
> Then:
> service ntpd stop
> ntpdate ntpgmtaceb
> 12 Apr 21:46:22 ntpdate[9860]: adjust time server offset
> -0.000252
> sec
> service ntp start
> ntpq -p
>      remote           refid      st t when poll reach   delay
> offset  jitter
> ==============================================================================
> *ntpgmtaceb      .1PPS.           1 u   20   64  377    0.144
> -0.373   0.863
> So it's seems to be really better, isn't it?

Delay on that connection is 0.144 vs 29.431 your original message
so it's probably "better" because of that rather than removal of
LOCAL(0). If original figure from delay was correct, eg due to
network load, then you'd need to get that fixed.

If using a recent ntpd you can have "tos orphan 10" to fallback
to local clock if it's sufficiently reliable, and other tos
options to set limits on what time if any is accepted and reported.

What version of ntpd are you running?


More information about the questions mailing list