[ntp:questions] Help: fudge time2 value for NMEA driver

Paul tik-tok at bodosom.net
Wed Nov 2 23:51:26 UTC 2016


On Sun, Oct 30, 2016 at 1:29 PM, ogre up <orgeup at gmail.com> wrote:

> Hello everyone, I've setup a NMEA+PPS ntp server, but both ref clock have
> strange offset value reported by ntpq -p.
>

Your billboard is fine.  If you want less jitter in your NMEA sentences you
need to buy better hardware.  Not necessarily more expensive but better.
However it doesn't matter as long as you stay within a few hundred
milliseconds of the correct second since the timing is done with PPS and
the GPS output is only used to number the seconds.  Unfortunately I have no
experience with your PPS problem.

I prefer using ATOM (PPS) + a GPS specific driver.  In the past I've been
unhappy using the PPS option in the NMEA driver so I don't bother.

Output from a low jitter NMEA compatible GPSDO:
     remote           refid      st t when poll reach   delay   offset
jitter
==============================================================================
o127.127.22.0    .GPPS.           0 l    2    8  377    0.000    0.000
0.002
*127.127.20.0    .FURY.           0 l    1    8  377    0.000   -0.003
0.011


More information about the questions mailing list