[ntp:questions] xGPS_NMEA / xPPS

TomK forensic at milwpc.com
Fri Feb 24 11:28:57 UTC 2012


  GPS PPS is not really flawless. It's reasonably dependable. If you can 
repeat the error, it's almost always software. It looks like the GPS 
lost a fix on at least 3 satellites, so PPS didn't sync. NTP noticed, 
and switched to 'NMEA sentence' time only. Check on satellite fix when 
that happens.




On 02/24/12 05:45, Alby VA wrote:
>
>   I've watched as my NTP session has gone between normal and falsetick.
> Anybody want to toss out an idea of why this is happening and the
> solution to make it stop?
>
>
>       remote           refid      st t when poll reach   delay
> offset  jitter
> ==============================================================================
> -ntp.alaska.edu  .GPS.            1 u   69  128    7  127.532
> 0.581  19.471
> +utcnist2.colora .ACTS.           1 u   69  128    7   61.424
> 15.184  16.376
> *time-a.nist.gov .ACTS.           1 u   70  128    7   16.060
> 26.839  25.833
> +tick.usask.ca   .GPS.            1 u   75  128    7  106.332
> 20.798  24.112
> -cronos.cenam.mx .GPS.            1 u   68  128    7   81.165
> 1.985  11.542
> xPPS(0)          .PPS.            0 l   13   16  377    0.000
> 28.105   3.330
> xGPS_NMEA(0)     .GPSb.           0 l   12   16  377    0.000
> -11.920   5.476
>
>
>
>
>
>       remote           refid      st t when poll reach   delay
> offset  jitter
> ==============================================================================
> +ntp.alaska.edu  .GPS.            1 u   75  128    7  127.532
> 0.581  19.471
> -utcnist2.colora .ACTS.           1 u   75  128    7   61.424
> 15.184  16.376
> -time-a.nist.gov .ACTS.           1 u   76  128    7   16.060
> 26.839  25.833
> -tick.usask.ca   .GPS.            1 u   81  128    7  106.332
> 20.798  24.112
> +cronos.cenam.mx .GPS.            1 u   74  128    7   81.165
> 1.985  11.542
> oPPS(0)          .PPS.            0 l    3   16  377    0.000
> 28.630   3.022
> *GPS_NMEA(0)     .GPSb.           0 l    2   16  377    0.000
> -25.386  12.305
>
>
>
> ** Ignore the low reach. I just restarted ntpd.
>
>
> _______________________________________________
> questions mailing list
> questions at lists.ntp.org
> http://lists.ntp.org/listinfo/questions



More information about the questions mailing list