| [chrony-users] trying to get Chrony to work with gpsd/PPS GPS |
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Listers,
I was using NTPD with the following configuration for the GPS (Garmin 18xLVC):
### /etc/ntp.conf
driftfile /var/lib/ntp/drift
server clock.fmt.he.net noselect
server ntp-1.vt.edu noselect
server clock.nyc.he.net noselect
server time-b.nist.gov noselect
# Garmin GPS 18 LVC
server 127.127.20.0 mode 0 minpoll 4 maxpoll 4 prefer
fudge 127.127.20.0 time2 0.600 flag1 1 flag2 0 flag3 1 refid PPS
It would report offsets of about 0.001 with low jitter as well.
Trying to use the same unit with chrony + gpsd and this configuration:
# Internet sources
server clock.fmt.he.net noselect
server ntp-1.vt.edu noselect
server clock.nyc.he.net noselect
server time-b.nist.gov noselect
refclock SHM 0 offset -0.6 delay 0.5 refid NEMA noselect
refclock SHM 1 offset -0.6 precision 1e-9 lock NEMA refid PPS
# Record the rate at which the system clock gains/losses time.
driftfile /var/lib/chrony/drift
Yields wildly varying offsets :(
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#? NEMA 0 4 377 9 +675ms[ +675ms] +/- 253ms
#* PPS 0 4 377 8 +7747ns[+8253ns] +/- 5644ns
^? clock.fmt.he.net 1 6 377 55 -600ms[ -600ms] +/- 35ms
^? ntp-1.ipv6.vt.edu 2 6 377 53 -601ms[ -601ms] +/- 35ms
^? clock.nyc.he.net 1 6 377 54 -600ms[ -600ms] +/- 7765us
^? time-b.nist.gov 1 6 377 55 -600ms[ -600ms] +/- 6549us
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#? NEMA 0 4 377 10 +669ms[ +669ms] +/- 253ms
#* PPS 0 4 377 8 +2954ns[+2721ns] +/- 5613ns
^? clock.fmt.he.net 1 6 377 38 -600ms[ -600ms] +/- 35ms
^? ntp-1.ipv6.vt.edu 2 6 377 36 -601ms[ -601ms] +/- 36ms
^? clock.nyc.he.net 1 6 377 101 -600ms[ -600ms] +/- 7765us
^? time-b.nist.gov 1 6 377 37 -600ms[ -600ms] +/- 6610us
Chronyc tracking
Reference ID : 50505300 (PPS)
Stratum : 1
Ref time (UTC) : Thu Sep 07 22:48:47 2017
System time : 0.000001081 seconds fast of NTP time
Last offset : +0.000000692 seconds
RMS offset : 0.000000814 seconds
Frequency : 22.380 ppm fast
Residual freq : +0.000 ppm
Skew : 0.010 ppm
Root delay : 0.000000001 seconds
Root dispersion : 0.000015589 seconds
Update interval : 16.0 seconds
Leap status : Normal
GPSMon Screenshot:
https://img.bsd-unix.net/screenshots/user1/2850Ab83e.png
ntpshmmon output:
# Name Seen@ Clock Real L Prec
sample NTP0 1504824422.059456899 1504824422.059016714 1504824422.000000000 0 -1
sample NTP1 1504824422.400228108 1504824422.399984786 1504824423.000000000 0 -20
sample NTP0 1504824422.559968988 1504824422.059016714 1504824422.000000000 0 -1
sample NTP1 1504824422.900433425 1504824422.399984786 1504824423.000000000 0 -20
sample NTP0 1504824424.045028574 1504824424.044241505 1504824424.000000000 0 -1
sample NTP1 1504824424.400442519 1504824424.399978781 1504824425.000000000 0 -20
sample NTP0 1504824424.545348968 1504824424.044241505 1504824424.000000000 0 -1
sample NTP1 1504824424.900928345 1504824424.399978781 1504824425.000000000 0 -20
sample NTP0 1504824426.041318136 1504824426.041166576 1504824426.000000000 0 -1
sample NTP1 1504824426.400096238 1504824426.399988587 1504824427.000000000 0 -20
sample NTP0 1504824426.541773498 1504824426.041166576 1504824426.000000000 0 -1
sample NTP1 1504824426.900437395 1504824426.399988587 1504824427.000000000 0 -20
sample NTP0 1504824428.051476959 1504824428.050505815 1504824428.000000000 0 -1
Any help would be appreciated!
--
Bryan G. Seitz
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