[ntp:questions] Falseticking with PPS

Nickolay Orekhov nowhere at mail.ru
Tue Nov 22 06:59:07 UTC 2011


Hello, all!

I have the following configuration on my client:
1 PPS signal delivered from some GPS receiver and 1 NTP server

Here's what I've got:
QNX Neutrino (localhost) (ttyp0)

ntpq> pe
     remote           refid      st t when poll reach   delay   offset
 jitter
==============================================================================
xPPS(1)          .PPSE.           0 l    5    8  377    0.000  -356.53
1.699
x10.0.0.197      .GPS.            1 u    4    8  377    0.316  84647.8
2.052
 10.0.0.198      .STEP.          16 u    -    8    0    0.000    0.000
0.000
ntpq>

Here's my config:

tos mindist 0.032
tinker panic 0 stepout 60

# PPS reference clock
server 127.127.22.1 maxpoll 3
fudge 127.127.22.1 refid PPSE

# External servers
server 10.0.0.197 prefer iburst maxpoll 3
server 10.0.0.198  iburst maxpoll 3

Ok, I see, they are both falsetickers because of great difference between
them. But why the difference is so great?
I think the difference between PPS signal and some other signal can't be
more than 1 second, isn't it?

May be I should increase tos mindist to be slightly greater than 1 second?

Thanks, Nick


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