cstankev...@toyon.com (Chris Stankevitz) writes: >Hello,
>I believe ntp is syncing to NMEA messages and not my PPS. I have some >specific questions below. >Facts: >1. My kernel is patched to support LinuxPPS Not needed. You can just use something like gpsd to use the shm hardware clock to run the pps. >2. ntpd-4.2.4 patched to support LinuxPPS >http://ftp.enneenne.com/pub/misc/linuxpps/refclocks/nmea/ ??? Patched? >3. I am using a Garmin GPS18 LVC with PPS tied to DCD >4. ntpd was configured with --disable-all-clocks --disable-parse-clocks >--enable-NMEA --enable-LOCAL-CLOCK Just why did you disable all clocks? >5. ntp.conf contains: >server 127.127.20.0 minpoll 4 prefer >server 127.127.20.0 flag3 1 flag2 0 >6. PPS signals are received by the kernel evidenced by entries in >/var/log/messages: >Jan 24 16:57:04 gps kernel: [ 136.314349] PPS event at 4294902783 >Jan 24 16:57:05 gps kernel: [ 136.947295] PPS event at 4294903033 >7. The NMEA clock is offset from a stratum 2 server by 600ms: >r...@gps:~/ntp-4.2.4p6# ntpq -p > remote refid st t when poll reach delay offset >jitter >============================================================================== > europium.canoni 193.79.237.14 2 u 13 64 1 154.790 548.684 > 0.001 > GPS_NMEA(0) .GPS. 0 l 11 16 1 0.000 -63.337 > 0.001 YOu must have set up your nmea to issue a huge bunch of sentences. Why not use the fudge to get the gps at least near the right ballpark. >8. ntpdc -c kern makes no reference to pps: >r...@gps:~/ntp-4.2.4p6# ntpdc -c kern >pll offset: -0.017965 s >pll frequency: 82.619 ppm >maximum error: 0.012304 s >estimated error: 1.6e-05 s >status: 0040 unsync >pll time constant: 4 >precision: 1e-06 s >frequency tolerance: 512 ppm >r...@gps:~/ntp-4.2.4p6# >9. According to ntpdc_ops.c, the pps variables are displayed only if >ik_shift evaluates to true. >Questions: >a) Why doesn't ik_shift evaluate to true in ntpdc_ops.c? >b) How can I confirm that ntp is aware of my PPS signal? >c) How can I get ntp to use PPS? I would just use the shmpps set of routines to set up pps using the shm refclock. _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions