[ntp:questions] NTP and PPS (and gpsd etc..)
david_anullo at itacosystems.com
Tue Apr 24 14:31:20 UTC 2007
I have a problem (Houston..). :-)
I must connect a Navman Jupiter 21 receiver to a linux-embedded machine.
I must also use PPS signal for accurate time to syncronize the internal
After a lot of various tests i have big trouble upon the utilization of ntp.
i have used:
1 gpsd (version: 2.32, 2.35beta) with ntpd (version: 4.1.1, 4.2.4,
4.2.5_24) (ntp.conf using shared memory 127.127.28.0/1)
2 only ntp (ntp.conf with NMEA/PPS 127.127.20.0/127.127.22.0)
3 a old Navman Jupiter 12 receiver (with Refclock Jupiter 127.127.31.0)
In the test 1, the ntpq -p show a offset upon SHM1-0 that without
warning jump to +/- 300/400 msec (ntpd sometimes show the "no new value
found" in shared memory)
In the test 2 i lost the PPS signal
In the test 3 i have a relevant excursion of peerstat offset (4 msec..)
In all test i have make various variations that i don't report to you..
this is only for example.
My question is: what i must to do with all this "instruments" to have a
stable time source for my machine? How i can use this strange PPS?
How i can make to obtain a syncronization time-source from this reicever
(or from a receiver)?
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