[ntp:questions] PPS refclock still requires the other prefer source to be whitin 128ms?

Nuno Gonçalves nunojpg at gmail.com
Sat Jul 29 18:18:59 UTC 2017


Hi!

For some reason my sources are being flagged falsetick, and it might
have to do that the prefer source have a +300ms offset. The
documentation before said that the prefer source had to be whitin
128ms, but now it just says 0.5s. Is the specification correct or am I
having another issue?

Using time1 on SHM to compensate the offset is not a option because
the offset can change from 50ms to 400ms in different conditions.

ntpq> peers
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
xSHM(0)          .SHM.            0 l   58   64  377    0.000  -345.70   4.141
xPPS(0)          .PPS.            0 l   16   16  377    0.000    0.010   0.016
ntpq> rv
associd=0 status=0028 leap_none, sync_unspec, 2 events, no_sys_peer,
version="ntpd 4.2.8p10 at 1.3728 Fri Jul 28 12:24:27 UTC 2017 (1)",
processor="armv7l", system="Linux/4.1.30-ti-r69", leap=00, stratum=1,
precision=-19, rootdelay=0.000, rootdisp=6.850, refid=PPS,
reftime=dd274b7b.5ad9dd04  Sat, Jul 29 2017 17:59:23.354,
clock=dd274d02.2840cc36  Sat, Jul 29 2017 18:05:54.157, peer=0, tc=4,
mintc=3, offset=0.000020, frequency=-43.791, sys_jitter=0.007600,
clk_jitter=0.018, clk_wander=1.251
ntpq> as

ind assid status  conf reach auth condition  last_event cnt
===========================================================
  1  7388  911a   yes   yes  none falsetick    sys_peer  1
  2  7389  911a   yes   yes  none falsetick    sys_peer  1
ntpq> rv 7388
associd=7388 status=911a conf, reach, sel_falsetick, 1 event, sys_peer,
srcadr=SHM(0), srcport=123, dstadr=127.0.0.1, dstport=123, leap=00,
stratum=0, precision=-1, rootdelay=0.000, rootdisp=0.000, refid=SHM,
reftime=dd274d00.57aacd9f  Sat, Jul 29 2017 18:05:52.342,
rec=dd274d00.5adeffa7  Sat, Jul 29 2017 18:05:52.354, reach=377,
unreach=0, hmode=3, pmode=4, hpoll=6, ppoll=6, headway=0, flash=00 ok,
keyid=0, ttl=0, offset=-345.499, delay=0.000, dispersion=1.039,
jitter=2.993,
filtdelay=     0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00,
filtoffset= -345.50 -345.70 -344.91 -344.63 -346.50 -345.79 -339.23 -340.90,
filtdisp=      0.12    1.05    2.02    3.00    3.98    4.96    5.86    6.85
ntpq> rv 7389
associd=7389 status=911a conf, reach, sel_falsetick, 1 event, sys_peer,
srcadr=PPS(0), srcport=123, dstadr=127.0.0.1, dstport=123, leap=00,
stratum=0, precision=-20, rootdelay=0.000, rootdisp=0.000, refid=PPS,
reftime=dd274d0b.00021d3f  Sat, Jul 29 2017 18:06:03.000,
rec=dd274d0b.5add06d1  Sat, Jul 29 2017 18:06:03.354, reach=377,
unreach=0, hmode=3, pmode=4, hpoll=4, ppoll=4, headway=0, flash=00 ok,
keyid=0, ttl=0, offset=-0.004, delay=0.000, dispersion=0.238,
jitter=0.009,
filtdelay=     0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00,
filtoffset=    0.00    0.00    0.01    0.01    0.00   -0.02   -0.01   -0.01,
filtdisp=      0.00    0.25    0.49    0.72    0.97    1.21    1.45    1.68

Thanks,
Nuno


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