[ntp:questions] Very large jitter and offsets on GPS ref clock after upgrade to "p5"

Chris Albertson albertson.chris at gmail.com
Fri Jan 6 03:44:36 UTC 2012


I just upgraded to 4.2.6p5 at 1.2349-o and I'm getting some odd results.
NTPD has been running for about 12 hours not on a Linux system.  The
following three "peers" displays were taken about one minute apart.
How do I go about debugging this?   Where to start?   The PPS coming
from the Oncore has less jitter on it than I can measure with an
HP5328 counter.  I shows a period of exactly 1,000,000 uSec.   I look
at "clockstats" and

ntpq> peers
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
oGPS_ONCORE(0)   .GPS.            0 l   14   16  357    0.000    0.004 377.962
+dev.factiondev. 66.220.9.122     2 u   18   64  377   44.131   -1.572   0.515
+bindcat.fhsu.ed 132.163.4.102    2 u   60   64  377   68.404    1.101   0.438
*ntp3.junkemailf 209.81.9.7       2 u   62   64  377   20.440   -1.842   0.862
-tds-solutions.n 167.23.176.214   3 u   17   64  377   45.344   -3.163   1.269
ntpq> peers
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*GPS_ONCORE(0)   .GPS.            0 l    6   16  327    0.000  999.997 999.996
+dev.factiondev. 66.220.9.122     2 u    6   64  377   43.754   -0.970   0.510
-bindcat.fhsu.ed 132.163.4.102    2 u   41   64  377   68.054    1.100   0.680
+ntp3.junkemailf 209.81.9.7       2 u   44   64  377   20.938   -1.328   0.524
-tds-solutions.n 167.23.176.214   3 u    7   64  377   44.084   -2.274   1.075
ntpq> peers
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*GPS_ONCORE(0)   .GPS.            0 l    3   16  277    0.000   -0.003 377.964
+dev.factiondev. 66.220.9.122     2 u   61   64  377   43.754   -0.970   0.510
-bindcat.fhsu.ed 132.163.4.102    2 u   29   64  377   68.054    1.100   0.524
+ntp3.junkemailf 209.81.9.7       2 u   32   64  377   20.938   -1.328   2.476
-tds-solutions.n 167.23.176.214   3 u   62   64  377   44.084   -2.274   1.075
ntpq> ver
ntpq 4.2.6p5 at 1.2349-o Thu Jan  5 07:51:56 UTC 2012 (1)

I know you are going to ask so here are the config files

MODE 4
LAT    33 51 54.315
LONG -118 23 01.782
HT     25.56 M
DELAY 50 NS
ASSERT
SHMEM /var/log/ntpstats/ONCORE
POSN3D
MASK 0

****************************

driftfile /var/lib/ntp/ntp.drift
statsdir /var/log/ntpstats/
logconfig =all
statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable

disable auth

# Connect to Oncore UT+ GPS
server 127.127.30.0  prefer

server 0.us.pool.ntp.org
server 1.us.pool.ntp.org
server 2.us.pool.ntp.org
server 3.us.pool.ntp.org

******************************

Chris Albertson
Redondo Beach, California


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