[ntp:questions] Sure GPS - Very High Jitter and Offset
mlichvar at redhat.com
Tue Aug 16 14:53:37 UTC 2011
On Tue, Aug 16, 2011 at 09:42:09AM -0500, Ken Link wrote:
> I wrote a script to compare the previous/current assert timestamp
> (ignoring the seconds), and this is what I get when NTP is *not*
That looks good.
> I tried setting flag3 to 0 but it didn't appear to make a difference.
> Also, I would have expected NTP to mark the clock as a PPS source with
> 'o', but when I let it sync it seems to stick with '*' instead:
> $ ntpq -p
> remote refid st t when poll reach delay offset jitter
> LOCAL(0) .LOCL. 12 l 232 64 10 0.000 0.000 0.002
> *GPS_NMEA(0) .GPS. 0 l 7 16 377 0.000 20.012 26.423
It seems the GPS driver is not getting or is ignoring the PPS signal.
I think there were some issues fixed recently in it. I'd try the ATOM
driver (22) first to verify ntpd was compiled with PPS support and is
able to use it.
More information about the questions