[ntp:questions] NTP with GPS + PPS falsetick

Marc Leclerc marc-leclerc at signaturealpha.com
Tue Jun 15 14:46:36 UTC 2010


Hi,

So it seem that after a while NTP reject my GPS and PPS input for time 
keeping. The only source for time sync is the GPS, I cannot use other 
devices and/or remote servers.

I had to add support for my receiver (Trimble Resolution SMT) and 
communication wise seems to communicate ok. The pps is also working.

Can anyone make sense of the output from ntpq -p and as cmd from ntpq 
and maybe help in understanding whats happening.

if there is any extra info needed please let me know

Thanks



my config is:

driftfile /etc/ntp.drift

server 127.127.29.1 mode 5 iburst prefer
server 127.127.22.0

#I tried with and without delay
#packet delay
#fudge 127.127.29.1 time1 0.020

At start

ntpq> as

ind assid status  conf reach auth condition  last_event cnt
===========================================================
   1 54000  802b   yes    no  none    reject clock_alarm  2
   2 54001  8011   yes    no  none    reject    mobilize  1
ntpq> as

ind assid status  conf reach auth condition  last_event cnt
===========================================================
   1 54000  802b   yes    no  none    reject clock_alarm  2
   2 54001  8011   yes    no  none    reject    mobilize  1
ntpq> as

ind assid status  conf reach auth condition  last_event cnt
===========================================================
   1 54000  9654   yes   yes  none  sys.peer   reachable  5
   2 54001  8011   yes    no  none    reject    mobilize  1


/ # ntpq -p
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l    8   16  377    0.000   -0.538   
0.141
  PPS(0)          .PPS.            0 l    -   64    0    0.000    
0.000   0.000

 >> Note the offset getting larger...

/ # ntpq -p
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l    1   16  377    0.000   -0.838   
0.233
  PPS(0)          .PPS.            0 l    -   64    0    0.000    
0.000   0.000

/ # ntpq -p
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l   15   16  377    0.000   -0.931   
0.149
  PPS(0)          .PPS.            0 l    -   64    0    0.000    
0.000   0.000

/ # ntpq -p
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l    1   16  377    0.000   -1.582   
0.148
  PPS(0)          .PPS.            0 l    -   64    0    0.000    
0.000   0.000

/ # ntpq -p
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l    5   16  377    0.000   -1.524   
0.544
xPPS(0)          .PPS.            0 l   37   64    1    0.000  -114.56   
0.002
/ # ntpq -p
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l   14   16  377    0.000   -1.431   
0.606
xPPS(0)          .PPS.            0 l   62   64    1    0.000  -114.56   
0.002
/ # ntpq -p
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l    7   32  377    0.000   -2.086   
0.438
xPPS(0)          .PPS.            0 l    7   64    3    0.000  -112.39   
2.171
/ # ntpq -p
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l   14   32  377    0.000   -2.086   
0.438
xPPS(0)          .PPS.            0 l   14   64    3    0.000  -112.39   
2.171
/ # cat /etc/ntp.drift
2.203
/ # ntpq
ntpq> pe
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l   13   32  377    0.000   -1.679   
0.360
xPPS(0)          .PPS.            0 l   13   64   17    0.000  -109.26   
3.655
ntpq> as

ind assid status  conf reach auth condition  last_event cnt
===========================================================
   1 54000  9654   yes   yes  none  sys.peer   reachable  5
   2 54001  9124   yes   yes  none falsetick   reachable  2

ntpq> pe
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l    8   32  377    0.000   -0.690   
0.885
xPPS(0)          .PPS.            0 l   40   64   37    0.000  -107.76   
4.440
ntpq> as

ind assid status  conf reach auth condition  last_event cnt
===========================================================
   1 54000  9654   yes   yes  none  sys.peer   reachable  5
   2 54001  9124   yes   yes  none falsetick   reachable  2
ntpq> as

ind assid status  conf reach auth condition  last_event cnt
===========================================================
   1 54000  9654   yes   yes  none  sys.peer   reachable  5
   2 54001  9124   yes   yes  none falsetick   reachable  2
ntpq> pe
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l    2   32  377    0.000   -1.317   
0.413
xPPS(0)          .PPS.            0 l    2   64   77    0.000  -106.28   
5.237
ntpq> as

ind assid status  conf reach auth condition  last_event cnt
===========================================================
   1 54000  9654   yes   yes  none  sys.peer   reachable  5
   2 54001  9124   yes   yes  none falsetick   reachable  2
ntpq> pe
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*GPS_PALISADE(1) .GPS.            0 l    5   32  377    0.000   -0.564   
0.828
xPPS(0)          .PPS.            0 l   37   64   77    0.000  -106.28   
5.237
ntpq> as

ind assid status  conf reach auth condition  last_event cnt
===========================================================
   1 54000  9154   yes   yes  none falsetick   reachable  5
   2 54001  9124   yes   yes  none falsetick   reachable  2
ntpq> pe
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
xGPS_PALISADE(1) .GPS.            0 l    8   32  377    0.000   -1.193   
0.409
xPPS(0)          .PPS.            0 l    8   64  177    0.000  -104.82   
6.030







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