[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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