Le 17/10/2011 16:55, Bill Dailey a écrit :
I need an NTP guru for a couple NTP questions. I have my Fury GPSDO hooked
up to a linux (ubuntu) computer have offset in the "time-nuts" category
(less than a microsecond) with pps. I am wondering where to go from here so
I can actually quantify the precision (it is below the standard minimum for
ntpd and reads 0s offset). I presume I have to get a soekris unit,
descipline it and use freebsd and ntpns. Input?
ntpq only reports the data to a resolution of 1us, but if you have
loopstat logging enabled you can get resolution 1ns
$ ntpq -pn
remote refid st t when poll reach delay offset
jitter
==============================================================================
o127.127.22.1 .PPS1. 0 l 9 16 377 0.000 0.000
0.008
$ tail /var/log/ntp/loopstats
55851 56703.983 0.000000874 9.230 0.000007629 0.000015 4
55851 56719.984 0.000000546 9.230 0.000007629 0.000015 4
55851 56735.983 0.000000797 9.230 0.000007629 0.000014 4
55851 56751.984 0.000000957 9.230 0.000007629 0.000015 4
55851 56767.983 0.000000173 9.230 0.000007629 0.000014 4
55851 56783.983 0.000000589 9.230 0.000007629 0.000014 4
55851 56799.983 0.000000626 9.230 0.000007629 0.000014 4
55851 56815.983 0.000000769 9.230 0.000007629 0.000013 4
55851 56831.984 0.000000377 9.230 0.000007629 0.000013 4
55851 56847.983 0.000000563 9.230 0.000007629 0.000013 4
use gnuplot to get a graph
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