[ntp:questions] Trimble Resolution SMT on Ubuntu 12.04

Dave Hart hart at ntp.org
Thu Mar 29 18:35:02 UTC 2012


On Thu, Mar 29, 2012 at 17:17, G <geng_j at yahoo.com> wrote:
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
>  GPS_NMEA(1)     .GPS.            0 l    -    8    0    0.000    0.000   0.000
>  caustique.anox. .INIT.          16 u    -   64    0    0.000    0.000   0.000
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> *GPS_NMEA(1)     .GPS.            0 l    2    8    7    0.000  -73.419  22.031
>  caustique.anox. .INIT.          16 u    -   64    0    0.000    0.000   0.000
>
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> *GPS_NMEA(1)     .GPS.            0 l    5    8  377    0.000    4.693   3.906
>  caustique.anox. .INIT.          16 u    -   64    0    0.000    0.000   0.000
> root at test12041:/home/test# ntpq -p
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> *GPS_NMEA(1)     .GPS.            0 l    -    8  377    0.000    4.945   3.906
>  caustique.anox. .INIT.          16 u    -   64    0    0.000    0.000   0.000
> root at test12041:/home/test# ntpq -p
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> oGPS_NMEA(1)     .GPS.            0 l    2    8  377    0.000   -0.581   3.906
>  caustique.anox. .STEP.          16 u    - 1024    0    0.000    0.000   0.000
>
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> oGPS_NMEA(1)     .GPS.            0 l    2    8  377    0.000    0.105   3.906
>  caustique.anox. .STEP.          16 u    - 1024    0    0.000    0.000   0.000
>
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> oGPS_NMEA(1)     .GPS.            0 l    1    8  377    0.000    0.838   3.906
>  caustique.anox. 128.233.150.93   2 u  698 1024    1    5.516  994.460   3.906
>
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> oGPS_NMEA(1)     .GPS.            0 l    7    8  377    0.000    1.849   3.906
>  caustique.anox. 128.233.150.93   2 u 1024 1024    1    5.516  994.460   3.906
>
>
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> xGPS_NMEA(1)     .GPS.            0 l    5    8  377    0.000    1.460   3.906
> xcaustique.anox. 128.233.150.93   2 u 59  64   377    4.457 995.520   3.906
>
> this is result for ntpd 3hours running .
>
> I guess not good . I will let it run over night to see what change.

It appears you've latched onto the wrong second, perhaps helped by
connectivity problems to the single pool server.  Once it became
reachable the problem is clear.  Use fudge time2 -0.600 so that ntpd
is steering the clock closer to correct when using only NMEA end of
sentence timestamps, so that when the clock is believed to be close
enough to engage PPS, it's indeed close and not close to a second off.

If you pay attention to the offset closely during startup, you can
tune time2 closer to minimize startup transients.

Cheers,
Dave Hart


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