[ntp:questions] timing issue with a HP 58534A

Mark C. Stephens marks at non-stop.com.au
Mon Feb 6 05:52:26 UTC 2012


Good, GPS working with ntpd in survey mode:

55963 19230.746 127.127.20.0 $GPRMC,052033,A,3345.8222,S,15105.5291,E,000.0,289.1,060212,012.8,E*66
55963 19247.246 127.127.20.0 $GPGGA,052050,3345.8223,S,15105.5289,E,1,08,02.23,000090.8,M,0020.5,M,,
55963 19263.246 127.127.20.0 $GPGGA,052106,3345.8217,S,15105.5271,E,1,08,02.23,000089.5,M,0020.5,M,,
55963 19279.246 127.127.20.0 $GPGGA,052122,3345.8218,S,15105.5275,E,1,08,02.23,000089.3,M,0020.5,M,,
55963 19295.246 127.127.20.0 $GPGGA,052138,3345.8226,S,15105.5297,E,1,08,02.23,000089.3,M,0020.5,M,,
55963 19311.246 127.127.20.0 $GPGGA,052154,3345.8238,S,15105.5298,E,1,08,02.23,000090.1,M,0020.5,M,,
55963 19327.246 127.127.20.0 $GPGGA,052210,3345.8234,S,15105.5279,E,1,08,02.23,000089.8,M,0020.5,M,,
55963 19343.246 127.127.20.0 $GPGGA,052226,3345.8241,S,15105.5282,E,1,08,02.23,000088.8,M,0020.5,M,,

Bad, GPS not working with NTPD when set to timing mode:

55963 19834.312 127.127.20.0 $GPGGA,053037,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,
55963 19846.818 127.127.20.0 $GPGGA,053047,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,
55963 19862.818 127.127.20.0 $GPGGA,053103,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,
55963 19878.818 127.127.20.0 $GPGGA,053119,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,
55963 19894.818 127.127.20.0 $GPGGA,053135,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,
55963 19910.818 127.127.20.0 $GPGGA,053151,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,
55963 19926.818 127.127.20.0 $GPGGA,053207,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,
55963 19942.818 127.127.20.0 $GPGGA,053223,3345.8218,S,15105.5278,E,0,07,00.38,000090.0,M,0020.5,M,,
55963 19958.818 127.127.20.0 $GPGGA,053239,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,
55963 19974.818 127.127.20.0 $GPGGA,053255,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,
55963 19990.818 127.127.20.0 $GPGGA,053311,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,

Good, GPS working with ntpd in survey mode:

ntpq> rv 23560
associd=23560 status=965a conf, reach, sel_sys.peer, 5 events, sys_peer, srcadr=GPS_NMEA(0), srcport=123, dstadr=127.0.0.1, dstport=123, leap=00, stratum=0, precision=-9, rootdelay=0.000, rootdisp=0.000, refid=GPS, 
reftime=d2d9e2be.fa22ad64  Mon, Feb  6 2012 16:25:18.977, rec=d2d9e2bf.3f03e586  Mon, Feb  6 2012 16:25:19.246, 
reach=377, unreach=0, hmode=3, pmode=4, hpoll=4, ppoll=4, headway=0, flash=00 ok, 
keyid=0, ttl=0, offset=2497.962, delay=0.000, dispersion=0.238, jitter=0.542, 
filtdelay=     0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00,
filtoffset= 2497.96 2498.08 2498.17 2498.28 2498.50 2498.59 2498.68 2498.79, 
filtdisp=      0.01    0.25    0.49    0.73    0.97    1.21    1.45    1.69

Bad, GPS not working with NTPD when set to timing mode:

ntpq> rv 43305
associd=43305 status=8011 conf, sel_reject, 1 event, mobilize,srcadr=GPS_NMEA(0), srcport=123, dstadr=127.0.0.1, dstport=123, 
leap=11, stratum=0, precision=-9, rootdelay=0.000, rootdisp=0.000, refid=GPS, 
reftime=00000000.00000000  Thu, Feb  7 2036 17:28:16.000, rec=00000000.00000000  Thu, Feb  7 2036 17:28:16.000, 
reach=000, unreach=0, hmode=3, pmode=4, hpoll=4, ppoll=4, headway=0, flash=1200 peer_stratum, peer_unreach, 
keyid=0, ttl=0, offset=0.000, delay=0.000, dispersion=15937.500, jitter=0.000,
filtdelay=     0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00,
filtoffset=    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00,
filtdisp=   16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0 16000.0

Good, GPS working with ntpd in survey mode:

ntpq> cv 23560
associd=23560 status=0000 , no events, clk_unspec, device="NMEA GPS Clock",
timecode="$GPGGA,052557,3345.8224,S,15105.5288,E,1,08,02.22,000089.0,M,0020.5,M,,",
poll=21, noreply=0, badformat=0, baddata=0, fudgetime1=0.000, stratum=0, refid=GPS, flags=1

Bad, GPS not working with NTPD when set to timing mode:

ntpq> cv 43305
associd=43305 status=0000 , no events, clk_unspec, device="NMEA GPS Clock",
timecode="$GPGGA,054142,3345.8218,S,15105.5278,E,0,08,00.35,000090.0,M,0020.5,M,,",
poll=42, noreply=0, badformat=0, baddata=0, fudgetime1=0.000, stratum=0, refid=GPS, flags=1


Footnote:
To further complicate matters, I wired up a tee cable and sent the NMEA to another NTP server here running windows NTPD 4.2.7p238-o.
NMEA works fine on that server in either mode.

Is the only difference the nmea gga fix word?


Many thanks,
Mark




-----Original Message-----
From: Dave Hart [mailto:hart at ntp.org] 
Sent: Monday, 6 February 2012 6:48 AM
To: Mark C. Stephens
Cc: questions at lists.ntp.org
Subject: Re: [ntp:questions] timing issue with a HP 58534A

On Sun, Feb 5, 2012 at 19:23, Mark C. Stephens <marks at non-stop.com.au> wrote:
> After capturing data and computing average position for location for a 
> few days I put it into timing mode and locked the co-ords in.
>
> Now the refclock driver says its unreachable, even though I can see 
> (looks like) valid data ticking in with -d.
>
> I have switched the GPS back to survey mode and all is good again, 
> looks like I can't use timing mode with this driver.

I'm curious what's going wrong when you have the HP GPS in timing mode.  While it's possible using -d (or -dd, or -ddd, or equivalently
-D2 or -D3) might be needed to isolate the cause, it's likely poking with ntpq will reveal all the information needed, using:

ntpq -c "rv &1"

and/or

ntpq -c "cv &1"

which display the generic peer variables and/or refclock-specific variables for the first peer/association.  If you haven't already, enable clockstats (such as with "statistics loopstats clockstats" in
ntp.conf) so the actual timecode received is logged, and do so _before_ switching back to position-locked timing mode.  Perhaps the difference that triggers the problem will become obvious.

Cheers,
Dave Hart




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