Re: [chrony-users] GPS / Chrony NTP server config questions

[ Thread Index | Date Index | More Archives ]

I have also not looked at the code recently but am suspicious. The time is
for example 1510691647.698064095 That is almost exactly half way between the
two seconds, and I think that the time needs to be within 1/4 sec of the top
of the second for chrony to think that there is a lock, and to start looking
at the time.

As Lichvar suggested, it would be a really great idea to connect your system
to the ethernet and to see what an ntp server somewhere else thinks is the
correct time. Two possibilities. One is that it is the clear edge of the pulse that needs to
be used as the top of the second. the second is that your nmea (GPS) time is
out by just about exactly 1/2 a second (which way I have no idea without some
other time source. )

William G. Unruh __| Canadian Institute for|____ Tel: +1(604)822-3273
Physics&Astronomy _|___ Advanced Research _|____ Fax: +1(604)822-5324
UBC, Vancouver,BC _|_ Program in Cosmology |____ unruh@xxxxxxxxxxxxxx
Canada V6T 1Z1 ____|____ and Gravity ______|_

On Tue, 14 Nov 2017, Joe Smith wrote:

I rebuilt chrony with --enable-debug and ran with -d -d  Below is some output although I'm
not 100% sure what it means. Tried looking at the source code to see if I could ascertain
the cause but I was unable. I let it run for a bit and here's some sample output. The
pattern just seems to repeat over and over.
2017-11-14T20:34:08Z refclock.c:765:(filter_add_sample) filter sample 0
t=1510691647.698064095 offset=-0.198064096 dispersion=0.000001833
2017-11-14T20:34:08Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003574796 sync=0 dist=1.500000000
2017-11-14T20:34:09Z refclock.c:765:(filter_add_sample) filter sample 1
t=1510691649.560963143 offset=-0.060963144 dispersion=0.000001833
2017-11-14T20:34:09Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003580218 sync=0 dist=1.500000000
2017-11-14T20:34:10Z refclock_shm.c:104:(shm_poll) SHM sample ignored mode=1 count=1202298
2017-11-14T20:34:10Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003583732 sync=0 dist=1.500000000
2017-11-14T20:34:11Z refclock.c:765:(filter_add_sample) filter sample 2
t=1510691651.549839364 offset=-0.049839365 dispersion=0.000001833
2017-11-14T20:34:11Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003582173 sync=0 dist=1.500000000
2017-11-14T20:34:12Z refclock_shm.c:104:(shm_poll) SHM sample ignored mode=1 count=1202302
2017-11-14T20:34:12Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003574833 sync=0 dist=1.500000000
2017-11-14T20:34:13Z refclock.c:765:(filter_add_sample) filter sample 3
t=1510691653.564970804 offset=-0.064970805 dispersion=0.000001833
2017-11-14T20:34:13Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003576043 sync=0 dist=1.500000000
2017-11-14T20:34:14Z refclock_shm.c:104:(shm_poll) SHM sample ignored mode=1 count=1202306
2017-11-14T20:34:14Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003574430 sync=0 dist=1.500000000
2017-11-14T20:34:15Z refclock.c:765:(filter_add_sample) filter sample 4
t=1510691654.612400335 offset=-0.112400336 dispersion=0.000001833
2017-11-14T20:34:15Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003573701 sync=0 dist=1.500000000
2017-11-14T20:34:16Z refclock.c:765:(filter_add_sample) filter sample 5
t=1510691656.599152919 offset=-0.099152920 dispersion=0.000001833
2017-11-14T20:34:16Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003564191 sync=0 dist=1.500000000
2017-11-14T20:34:17Z refclock.c:765:(filter_add_sample) filter sample 6
t=1510691657.519233732 offset=-0.019233733 dispersion=0.000001833
2017-11-14T20:34:17Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003540440 sync=0 dist=1.500000000
2017-11-14T20:34:18Z refclock.c:765:(filter_add_sample) filter sample 7
t=1510691658.565950335 offset=-0.065950336 dispersion=0.000001833
2017-11-14T20:34:18Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003555990 sync=0 dist=1.500000000
2017-11-14T20:34:19Z refclock.c:765:(filter_add_sample) filter sample 8
t=1510691659.612487851 offset=-0.112487852 dispersion=0.000001833
2017-11-14T20:34:19Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003554507 sync=0 dist=1.500000000
2017-11-14T20:34:20Z refclock_shm.c:104:(shm_poll) SHM sample ignored mode=1 count=1202318
2017-11-14T20:34:20Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003536535 sync=0 dist=1.500000000
2017-11-14T20:34:21Z refclock.c:765:(filter_add_sample) filter sample 9
t=1510691661.556102500 offset=-0.056102501 dispersion=0.000001833
2017-11-14T20:34:21Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003563863 sync=0 dist=1.500000000
2017-11-14T20:34:22Z refclock.c:765:(filter_add_sample) filter sample 10
t=1510691662.603828315 offset=-0.103828316 dispersion=0.000001833
2017-11-14T20:34:22Z refclock.c:520:(RCL_AddCookedPulse) refclock pulse ignored
offset=0.003559951 sync=0 dist=1.500000000
2017-11-14T20:34:23Z refclock_shm.c:104:(shm_poll) SHM sample ignored mode=1 count=1202324
2017-11-14T20:34:23Z sources.c:356:(SRC_AccumulateSample) ip=[NMEA] t=1510691656.723338336
ofs=0.080481 del=0.200000 disp=0.009623 str=0
2017-11-14T20:34:23Z sourcestats.c:583:(SST_DoNewRegression) off=1.007180e-01
freq=6.636850e-05 skew=3.159318e-04 n=16 bs=0 runs=10 asym=0.000000 arun=0

On Tue, Nov 14, 2017 at 10:36 AM, Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:
      On Tue, Nov 14, 2017 at 07:40:33AM -0500, Joe Smith wrote:
      > Thank you for the quick response Bill... The PPS is coming in on /dev/pps1
      > which is what I have in the refclock entry in my chrony.conf file. When run
      > the cat command corresponding to that device I get:
      > debian@beaglebone:~/ntp-gps-server/pps-overlay$ cat
      > /sys/devices/virtual/pps/pps1/assert
      > 1510661769.997836084#571264

      That looks good. The configuration also looks good. I guess the only
      thing that could be wrong is the offset value on the SHM line. Does
      the machine have an internet connection? It might help if you could
      configure it with an NTP server and remove the lock option from PPS to
      see if it works that way and to see if the offset of the NMEA source
      needs to be adjusted.

      If that doesn't work, recompiling chrony with debug support
      (--enable-debug) and running chronyd with -d -d should show why it's
      ignoring the PPS samples.

      Miroslav Lichvar

      To unsubscribe email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
      with "unsubscribe" in the subject.
      For help email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
      with "help" in the subject.
      Trouble?  Email listmaster@xxxxxxxxxxxxxxxxxxxx.

Mail converted by MHonArc 2.6.19+