[time-nuts] leontp offset?
David J Taylor
david-taylor at blueyonder.co.uk
Sat Oct 15 03:43:54 EDT 2016
Hi all,
I'm checking out the leontp ntp time server (leontp.com). After a week of
use I am getting the following ntp -q output:
$ ntpq -pn
remote refid st t when poll reach delay offset
jitter
==============================================================================
*172.17.21.11 .GPS. 1 u 13 16 377 0.137 0.077
0.054 <- Arbiter 1084C GPS Clock
+172.17.21.12 .GPS. 1 u 11 16 377 0.101 0.085
0.174 <- Arbiter 1084C GPS Clock
x172.17.21.233 .GPS. 1 u 11 16 377 0.071 9.760
0.061 <- LeoNTP
the offset of the leontp device from the other clocks has consistently been
in the 9.5 -10.5 range. since I'm measuring all three sources from the
same (EL7) computer, I would expect that the offset of the leontp unit to
converge to be in the close neighborhood of the offsets of the arbiters.
It has not converged, instead maintaining the ~10ms offset.
Thoughts?
Thanks.
_______________________________________________
Briefly,
Here is an Intel Atom Linux NTP server fed from a Garmin GPS 18 LVC compared
against some other devices, where 192.168.0.20 is a LeoNTP:
remote refid st t when poll reach delay offset
jitter
==============================================================================
o127.127.22.0 .kPPS. 0 l 5 16 377 0.000 0.000
0.003
*127.127.28.0 .GPSD. 0 l 6 16 377 0.000 -3.598
0.662
192.168.0.83 .kPPS. 1 u 2 32 377 0.251 0.006
0.017
192.168.0.20 .GPS. 1 u 16 32 377 0.087 0.028
0.002
+192.168.0.1 .kPPS. 1 u 4 32 377 0.161 -0.119
0.022
+192.168.0.7 .kPPS. 1 u 18 32 377 0.196 -0.043
0.027
+192.168.0.8 .kPPS. 1 u 2 32 377 0.160 -0.018
0.139
There's no 10 ms offset. Other devices are: .83 a Raspberry Pi, .1, .7 .8
Windows kernel-mode PPS synced server. I would suggest checking your
Arbiter servers.
Can you check with a 'scope to compare the PPS out out the LeoNTP? It's a
100 ms positive pulse, within about 50 ns of a couple of other GPS/PPS
devices, and about 200 ns earlier than a Jackson Labs device.
Cheers,
David
--
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Email: david-taylor at blueyonder.co.uk
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