[ntp:questions] Too much offset from GPS?
isw at witzend.com
Sat Mar 8 07:21:07 UTC 2008
In article <Z_jAj.87237$C61.22584 at edtnps89>,
Unruh <unruh-spam at physics.ubc.ca> wrote:
> Steve Kostecke <kostecke at ntp.org> writes:
> >On 2008-03-07, Hal Murray wrote:
> >>ATTRIBUTION MISSING wrote:
> >>>I have problem with my stratum1 box. My box include: freebsd
> >>>5.2-RELEASE without PPS , ntp-4.2.0_1, Intel Pentium III, 40 G IDE,
> >>>Germin GPSmap60 , connect with serial com. In GPSmap60 set as NMEA.
> >>>Freebsd box can get NMEA input string. My configuration of ntp.conf
> >>>like this:
> >>>server 127.127.20.0 mode 1 prefer minpoll 4
> >>>server 127.127.1.0 minpoll 5
> >> Most NMEA devices (or at least all the ones I've worked with)
> >> send their text with a significant offset.
> >It gets even better ... NMEA sentences are output by the GPS device
> >when it is not busy. This means that there is no fixed relationship
> >between the top of the second and the NMEA sentence. And there will be
> >significant jitter.
> Ie, NMEA is good for getting the second, not for getting any better
> accuracy (well maybe 1/10 sec) If you want accurate time get a gps with PPS
> Otherwise there is no advantage of NMEA over a network ntp connection.
Well, except for the "no wires" part...
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