In case of interest, I got NTP with PPS from a GPS receiver running on the
Raspberry Pi. My peak error (looking at the kernel's PPS timestamps) went from
about +/- 2 msec using remote NTP servers, to about 60 usec with PPS enabled
(limited by variability in the R-Pi's interrupt latency.) Using "Raspbian"
kernel compiled with PPS support. More info, and graphs at
http://www.raspberrypi.org/phpBB3/viewtopic.php?f=41&t=1970&start=25#p142606
pi@raspberrypi:~$ /usr/local/bin/ntpq -c peer -c as -c rl
remote refid st t when poll reach delay offset jitter
==============================================================================
*stratum-2-core- 129.7.1.66 2 u 53 64 377 63.748 -1.330 1.625
+four10.gac.edu 18.26.4.105 2 u 29 64 377 59.207 2.768 0.346
+sola-dal-09.ser 64.250.177.145 2 u 36 64 377 48.895 3.617 0.703
+tick.tadatv.com 10.0.22.51 2 u 55 64 377 10.340 2.228 0.148
oPPS(0) .PPS. 0 l 2 16 377 0.000 0.009 0.012
ind assid status conf reach auth condition last_event cnt
===========================================================
1 46881 963a yes yes none sys.peer sys_peer 3
2 46882 9424 yes yes none candidate reachable 2
3 46883 9424 yes yes none candidate reachable 2
4 46884 9424 yes yes none candidate reachable 2
5 46885 973a yes yes none pps.peer sys_peer 3
associd=0 status=011d leap_none, sync_pps, 1 event, kern,
version="ntpd [email protected] Mon Aug 6 02:06:19 UTC 2012 (1)",
processor="armv6l", system="Linux/3.1.9-pps+", leap=00, stratum=1,
precision=-19, rootdelay=0.000, rootdisp=0.288, refid=PPS,
reftime=d3ca91b1.315968df Mon, Aug 6 2012 11:55:45.192,
clock=d3ca91b3.f1638fef Mon, Aug 6 2012 11:55:47.942, peer=46885, tc=4,
mintc=3, offset=0.009, frequency=-37.252, sys_jitter=0.012,
clk_jitter=0.000, clk_wander=0.003
_______________________________________________
questions mailing list
[email protected]
http://lists.ntp.org/listinfo/questions
