Unruh wrote: [] > An hour later, it was still 7ms off, another hour, 2.6ms and another > hour > later, still 1.2 ms off. Ie, only after about 6 hours was it within a > ms of > the correct time. Now, usually this PPS controls the time to within > about 2us (not ms, usec) but it is apparently going to take over 10 > hours to get > there. That is of course completely rediculous.
There sounds to be something wrong with your system. As a comparison, I have a very old Pentium 133 system here running FreeBSD with local GPS PPS and some other Internet-based stratum 2/3 servers (probably NTP pool and a fixed name). I'm sure it's well within a few minutes for it to reach it's full accuracy (tens of microseconds). For interest, I've just (0645 UTC) switched it off and on, and we will be able to watch its recovery here (30 minute updates): http://www.satsignal.eu/mrtg/pixie_ntp.html Here it is about a minute after startup: ntpq -p pixie remote refid st t when poll reach delay offset jitter ============================================================================== +calx.pulsewidth 193.120.10.3 2 u 62 64 1 22.272 1.700 0.743 +admin.islay.bit 192.33.96.102 2 u 62 64 1 21.131 0.921 1.112 +dnscache-london 128.250.33.242 2 u 62 64 1 22.845 3.299 0.666 88-96-233-89.ds .PPS. 1 u 14 128 7 63.431 0.044 2.789 *utserv.mcc.ac.u 193.62.22.98 2 u 64 64 1 26.494 4.312 0.829 GPS_NMEA(1) .PPS. 0 l 12 64 3 0.000 -0.137 1.654 .. and a few minutes later ... ntpq -p pixie remote refid st t when poll reach delay offset jitter ============================================================================== +calx.pulsewidth 193.120.10.3 2 u 54 64 37 22.348 2.946 0.877 +admin.islay.bit 192.33.96.102 2 u 53 64 37 20.496 1.862 1.057 +dnscache-london 128.250.33.242 2 u 57 64 37 23.090 3.809 0.662 88-96-233-89.ds .PPS. 1 u 134 256 17 63.431 0.044 2.007 +utserv.mcc.ac.u 193.62.22.98 2 u 53 64 37 25.564 5.371 0.868 *GPS_NMEA(1) .PPS. 0 l 3 64 77 0.000 -0.001 0.803 It's using the out-of-the-box NTP code, and probably a rather old version of NTP. version="ntpd 4.2.0-a Sun May 8 06:01:21 UTC 2005 (1)" It's a very simple system, described here: http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm Cheers, David _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
