[ntp:questions] Running ntpd with PPS precision signal only
alexvm22 at gmail.com
Mon Mar 5 18:15:03 UTC 2012
Thanks for your help.
> Assuming you are not disconnecting the PPS by disconnecting the NMEA,
> if you want the PPS to survive NMEA outage you'll likely need to
> switch from unified NMEA+PPS driver to NMEA-only and PPS-only:
NMEA and PPS drivers work fine, but sometime after power on a time
diffrenece between NMEA and PPS is too big (about 3 secs) and I have
xGPS_NMEA(0) .NV24. 0 31d 16 377 0.000 2510.04 8.180
xPPS(0) .PPS. 0 31d 16 377 0.000
I think there isn't a synchronization between NMEA and PPS signals
though I found and set time2 properly.
> If that doesn't do the trick, also add one or more network servers
> with "prefer".
Unfortunately I can't use any network servers on my embedded system...
>I'm unsure at the moment if the PPS driver requires a
> reachable prefer peer continuously, or only to bootstrap. Also you
> may need a fudge time2 on the NMEA to offset its end-of-sentence
> timestamps to be closer to the preceding PPS timestamp -- the PPS
> driver requires the prefer peer(s) get the system clock offset
> relative to the PPS under 0.4s before the PPS is engaged.
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