NTP does not really "sync" to a server. What it does is "use the set of reference clocks that pas the clock selection criteria". THere is an algorithm that determines if a reference clock is reasonable or not. A reference clock can be a GPS or another NTP server or a cell phone service or any of a dozen other things but GPS and other servers are by far the most common.
Your RPI is three leves removed from a GPS. It is operating as "stratum 3" the second RPI is stratum 2. Both are doing really good for using a networked ref. clock. I would not blain the RPI. If you are doing better than a millisecond with no local PPS it is good. On Sun, May 26, 2013 at 9:15 AM, folkert <folk...@vanheusden.com> wrote: >> > Besides I got them to run NTP and they're too jittery for my taste. >> >> How good/bad were they? >> What were you using for a time source? Does it have PPS support? > > Here's ntpq -c pv for one of my RPIs after 25 days of uptime: > > associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync, > version="ntpd 4.2.6p5@1.2349-o Fri May 18 20:30:57 UTC 2012 (1)", > processor="armv6l", system="Linux/3.8.10+", leap=00, stratum=3, > precision=-20, rootdelay=25.184, rootdisp=73.646, refid=83.98.201.134, > reftime=d54cac1f.18aa9126 Sun, May 26 2013 17:43:27.096, > clock=d54cb273.b755933f Sun, May 26 2013 18:10:27.716, peer=34195, > tc=10, mintc=3, offset=0.182, frequency=-47.006, sys_jitter=0.377, > clk_jitter=0.558, clk_wander=0.051 > > Hmmm found out that it syncs to random hosts on the internet. > > Ok an other one which syncs against an other pc with PPS (and a few > others): > > folkert@weerpi ~ $ ntpq -c rv > associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync, > version="ntpd 4.2.6p5@1.2349-o Fri May 18 20:30:57 UTC 2012 (1)", > processor="armv6l", system="Linux/3.8.10+", leap=00, stratum=2, > precision=-20, rootdelay=0.807, rootdisp=7.669, refid=192.168.64.100, > reftime=d54cb1e1.9d6e8f07 Sun, May 26 2013 18:08:01.614, > clock=d54cb2e4.7d1cdae3 Sun, May 26 2013 18:12:20.488, peer=41936, tc=9, > mintc=3, offset=0.220, frequency=-31.405, sys_jitter=0.647, > clk_jitter=0.074, clk_wander=0.003 > > folkert@weerpi ~ $ uptime > 18:12:25 up 15 days, 3:48, 1 user, load average: 0.12, 0.17, 0.15 > > > Folkert van Heusden > > -- > Multitail est un outil permettant la visualisation de fichiers de > journalisation et/ou le suivi de l'exécution de commandes. Filtrage, > mise en couleur de mot-clé, fusions, visualisation de différences > (diff-view), etc. http://www.vanheusden.com/multitail/ > ---------------------------------------------------------------------- > Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.