2014-05-25
After testing the gps sky view it's now ...
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After testing the gps sky view it's now time to test with ntpd. First step was to recompile ntpd because the debian default package had no pps support. Recompiling on a 500 MHz AMD Geode takes a bit of time. Results look ok for a first test:root@ritchie:~# ntpq -p remote refid st t when poll reach delay offset jitter ============================================================================== +greenblatt.idef 131.211.8.244 2 u 17 64 377 1.177 101.732 63.403 *metronoom.dmz.c .PPS. 1 u 17 64 377 19.499 100.512 6.722 +auth1.xs4all.nl 193.67.79.202 2 u 11 64 377 18.403 104.008 3.669 oGPS_NMEA(0) .GPS. 0 l 6 8 377 0.000 114.073 7.364 root@ritchie:~# ntpdc -c loopi offset: 0.001986 s frequency: 94.434 ppm poll adjust: -30 watchdog timer: 342 s root@ritchie:~# ntpdc -c kerni pll offset: 3.3e-08 s pll frequency: 94.434 ppm maximum error: 0.175258 s estimated error: 2e-06 s status: 2007 pll ppsfreq ppstime nano pll time constant: 3 precision: 1e-09 s frequency tolerance: 500 ppm root@ritchie:~# ntpdc -c sysi system peer: GPS_NMEA(0) system peer mode: client leap indicator: 00 stratum: 1 precision: -19 root distance: 0.00000 s root dispersion: 0.00749 s reference ID: [GPS] reference time: d72cb010.dc91595e Sun, May 25 2014 20:08:16.861 system flags: auth monitor ntp kernel stats pps jitter: 0.006714 s stability: 0.000 ppm broadcastdelay: 0.000000 s authdelay: 0.000000 sIt will need some more calibration probably. Update: It keeps looking nice after some calibration. Stats gathered at NTP server ritchie.idefix.net stats. This does mean one of the old project sundial goals has been met: the weather station computer in the shed is now also a time server.