David J Taylor wrote: > 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 mentioned in another reply, AFAIR older versions of the NTP daemon did converge quite a bit faster than recent versions. > 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)" Now the question is how a recent version of ntpd would converge on this machine. Martin -- Martin Burnicki Meinberg Funkuhren Bad Pyrmont Germany _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
