[ntp:questions] Determine from logfiles if PPS/NMEA was discarded?

David Lord snews at lordynet.org
Fri Jan 3 13:13:51 UTC 2014


Ralph Aichinger wrote:
> I've had to rebuild my NTP server, and have had problems of
> ntp somehow "losing" the GPS with offsets of 1 second (wrong
> side of the PPS) and/or huge (100ms+) sporadic jitters since.
> 
> I'm not sure if I've solved it, but configuring out unneded
> sentences, fiddling with time2 (400ms now) seems to have 
> vastly improved it, or solved it completely.
> 
> Is there a way to find out afterwards, if the NMEA has had
> a problem (e.g. tally "x" discarded by intersection algorithm,
> or losing the "o" of the PPS signal in peer display) while
> I was not looking?
> 
> The peerstats/clockstats file is a bit cryptic to me.
> 
> Thanks in advance,
> 
> /ralph

I use peer_summary and loop_summary but they are not suitable
for diplaying short term glitches. I also have a crontab
*/6 *   *   *   *   /bin/sh /root/scripts/ntp/ntp_stat.sh

Fri Jan  3 12:54:00 GMT 2014
      remote   refid     st t when poll reach   delay   offset  jitter
=====================================================================
-GPS_NMEA(2)  .GPSb.     7 l    7   64  377    0.000  -23.293   5.274
oPPS(2)       .PPSb.     0 l    6   16  377    0.000   -0.005   0.004
+ns0.lordynet 81.187.61  3 u   60   64  377    1.592    0.442   0.586
  ns2.lordynet 192.168.5  2 u   26   64  377    0.665   -0.179   0.406
+ns1.lordynet 81.187.61  3 u   18   64  377    0.642    0.290   0.557
+ns3.lordynet 81.187.61  3 u   34   64  377    0.825    0.263   0.658
*ntp1.xxxxxxx 195.66.24  2 u   41  256  377   23.172   -0.069   0.465
ntp_gettime() returns code 0 (OK)
   time d6713169.300d801c  Fri, Jan  3 2014 12:54:01.187, (.187706104),
   maximum error 403500 us, estimated error 2 us, TAI offset 35
ntp_adjtime() returns code 0 (OK)
   modes 0x0 (),
   offset -5.040 us, frequency -36.693 ppm, interval 256 s,
   maximum error 403500 us, estimated error 2 us,
   status 0x2107 (PLL,PPSFREQ,PPSTIME,PPSSIGNAL,NANO),
   time constant 4, precision 0.001 us, tolerance 496 ppm,
   pps frequency -36.693 ppm, stability 0.021 ppm, jitter 2.800 us,
   intervals 1030, jitter exceeded 877, stability exceeded 0, errors 3.


David



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