[ntp:questions] NTP server with Garmin GPS 18 LVC
Adrian P
ntp at pascalau.ro
Mon Dec 16 11:16:15 UTC 2013
Hi,
In an old IBM thinkpad T22 laptop that runs FreeBSD 9.2, I have
configured a NTP server that gets the PPS signal from a Garmin GPS 18
LVC, as described here:
http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm
The /etc/ntp.conf contains the following generic NMEA GPS receiver
driver configuration:
server 127.127.20.0 mode 1 minpoll 4 maxpoll 4 prefer
fudge 127.127.20.0 flag1 1 flag2 0 flag3 1 refid PPS
I let it run for a few days, however I still have every now and then
huge peaks (between -50 and +30 us) of the clock offset as seen in the
following graph: http://goo.gl/JpSyeO
So I am wondering: why those repeating huge clock offsets? They
allays starts with a negative peak, followed immediately by a positive
one. Is this because of the faulty laptop internal clock, that drifts
away with 30-40 us every now and then? Any thoughts?
Many thanks,
Adrian
More information about the questions
mailing list