[ntp:questions] TSIP and PPS can't synchronize after start

David Lord snews at lordynet.org
Wed Dec 26 18:54:12 UTC 2012


Nickolay Orekhov wrote:
> Hello!
> 
> I've got a QNX machine with external Trimble TSIP receiver and PPS going
> through serial port ( but supplied by another additional driver ).
> Here's my config:
> 
> # midist  : increased minimal distance for PPS reference clocks ( default
> 0.001s )
> tos mindist 0.128
> 
> # panic   : zero to accept initial big shifts ( default 1000s )
> # stepout : how many seconds wait before stepping to spike ( default 900s )
> # step    : step threshold in seconds ( default 0.128s )
> tinker panic 0 stepout 60
> 
> # TSIP reference clock
> server 127.127.8.2 mode 138 prefer maxpoll 3 true
> fudge 127.127.8.2 refid TSIP time1 0.08 stratum 8
> 
> Here's ntpq output:
> 
> # /usr/sbin/ntpq 10.1.1.210
> 
> ntpq> rv
> associd=0 status=0018 leap_none, sync_unspec, 1 event, no_sys_peer,
> version="ntpd 4.2.7p164 at 1.2483 Mon Sep 10 04:54:12 UTC 2012 (1)",
> processor="x86pc", system="QNX/6.5.0", leap=00, stratum=9, precision=-20,
> rootdelay=0.000, rootdisp=1284.075, refid=GENERIC(2),
> reftime=d4857ad1.534b73e5  Wed, Dec 26 2012 19:32:01.325,
> clock=d4857b83.589b9099  Wed, Dec 26 2012 19:34:59.346, peer=0, tc=3,
> mintc=3, offset=13.009, frequency=-16.969, sys_jitter=485.290,
> clk_jitter=3.690, clk_wander=0.000, last_step=0.000, step_cntr=0
> 
> ntpq> pe
>      remote           refid      st t when poll reach   delay   offset
>  jitter
> ==============================================================================
> xGENERIC(2)      .TSIP.           8 l    4    8  377    0.000  -394.19
> 459.192

You are a falseticker because offset is more than the mindidt=0.128

Depending on your ntpd version I'd suggest setting a  mindist=0.45
for a start and monitoring the offset for a while to get a good
value for offset variation, after which change your "fudge time1"
to middle of that offset range and you will probably then be able
to reduce the mindist value.


David

> ntpq> ass
> 
> ind assid status  conf reach auth condition  last_event cnt
> ===========================================================
>   1 37217  913a   yes   yes  none falsetick    sys_peer  3
> ntpq> cv 37217
> associd=37217 status=0020 2 events, clk_unspec,
> device="Trimble GPS (TSIP) receiver", timecode="\x10M-^B\x02\x10\x03",
> poll=30, noreply=0, badformat=0, baddata=1, fudgetime1=80.000, stratum=8,
> refid=84.83.73.80, flags=0,
> refclock_ppstime="d4857b8a.89b415be  Wed, Dec 26 2012 13:35:06.537",
> refclock_time="d4857b89.b8000000  Wed, Dec 26 2012 13:35:05.718",
> refclock_status="TIME CODE; PPS; POSITION; (LEAP INDICATION; PPS SIGNAL;
> POSITION)",
> refclock_format="Trimble TSIP",
> refclock_states="*NOMINAL: 00:03:51 (97.46%); ILLEGAL DATE: 00:00:06
> (2.53%); running time: 00:03:57",
> trimble_version="1.16 (1906/2/2)", trimble_iooptions="00 00 23 00",
> trimble_satview="mode: 2D-AUTO, PDOP 0.00, HDOP 0.00, VDOP 0.00, TDOP 0.00,
> 2 satellites in view: 01, 11",
> trimble_receiver_health="doing position fixes",
> trimble_status="machine id 0x5a, Superpackets supported", satellites=2
> ntpq> rv 37217
> associd=37217 status=913a conf, reach, sel_falsetick, 3 events, sys_peer,
> srcadr=GENERIC(2), srcport=123, dstadr=127.0.0.1, dstport=123, leap=00,
> stratum=8, precision=-20, rootdelay=0.000, rootdisp=0.000, refid=TSIP,
> reftime=d4857b89.b8000000  Wed, Dec 26 2012 19:35:05.718,
> rec=d4857b8a.53bba453  Wed, Dec 26 2012 19:35:06.327, reach=377,
> unreach=0, hmode=3, pmode=4, hpoll=3, ppoll=3, headway=0, flash=00 ok,
> keyid=0, ttl=0, offset=-333.209, delay=0.000, dispersion=347.336,
> jitter=421.221,
> filtdelay=     0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00,
> filtoffset= -333.21 -394.19  275.11 -412.30  364.76 -344.66 -393.18  275.94,
> filtdisp=    320.63  377.33  378.43  356.35  437.03  321.96  376.95  379.26
> 
> ntpq>
> 
> Also here's output from my pps driver:
> 
> # cat /dev/pps0
> C 1356529006.540260352
> C 1356529007.540283136
> C 1356529008.540306176
> C 1356529009.540329984
> C 1356529010.540353792
> 
> Here you can see that timestamps are in the middle of the second.
> I know that PPS driver is working and if i divide PPS and GPS into two
> sources everything is fine. Also GPS without PPS also works fine.
> If i restart ntpd in most cases it will be ok.
> 
> Please, could you make suggestions on the following questions:
> 
> 1. Why source is falseticker? I thought that source can become falseticker
> only if ntpd has two or more sources declared.
> 2. Why it can't synchronize in this way ( but works fine with separated
> sources and GPS without PPS )
> 
> Thanks, Nickolay Orekhov



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