[ntp:questions] clockvar output from PPS

unruh unruh at invalid.ca
Tue Feb 21 16:26:58 UTC 2012

On 2012-02-21, Alby VA <albyva at empire.org> wrote:
> David:
>  With your Sure GPS showing "PPS Clock Discipline", what does your
> ntp.conf file look like? I ask, because if I list == server
> ==
> I don't get anything (even though I did the soldering per
> http://www.satsignal.eu/ntp/Sure-GPS.htm
> But when I list == server == is works just fine.  I also
> have
> a link of ln -s /dev/cuau0 /dev/pps0 and ln -s /dev/cuau0 /dev/gps0

??? the format of pps0 output is nothing like the format of the output of
the serial port as far as I know. 
If you are going to use pps, you have to set up your serial port to run
interrupts and to report those interrupts. On linux, you have to load
the modules pps_core and pps_ldisc and then link the serial port dcd
line to the pps_ldisc using ldattach 18. That creates a pps0 device in
/dev and in /sys/class/pps/pps0/. I suspect similar things are needed in

Ie, It is NOT sufficient to simply wire up the sure board, plug it in
and run the atom driver. You also have to tell you system to timestamp
and report its serial line interrupts. 

> Is that similar to your setup?
> Thanks,
> godzilla# ntpq -c clockvar
> assID=0 status=0000 clk_okay, last_clk_okay,
> device="NMEA GPS Clock",
> timecode="$GPGGA,144531.000,3903.1142,N,07729.1024,W,
> 1,6,1.52,111.2,M,-33.4,M,,*61",
> poll=3053, noreply=0, badformat=0, baddata=0, fudgetime1=0.000,
> stratum=0, refid=GPS, flags=5
> godzilla#
> On Feb 20, 6:59?am, David Lord <sn... at lordynet.org> wrote:
>> This is from my system with Sure GPS.
>> Seems to be similar to yours. I don't have a clue as to stratum and
>> refid as this is first time I've used ntpq clockvar.
>> associd=0 status=00f1 , 15 events, clk_no_reply,
>> device="PPS Clock Discipline", timecode=, poll=96503, noreply=300,
>> badformat=o, baddata=0, fudgetime1=0.000, stratum=16,refid=,
>> flags=4
>> associd=0 status=0119 leap_none, sync_pps, 1 event, leap_armed,
>> version="ntpd 4.2.... at 1.2349-o Tue Dec 27 09:47:55 UTC 2011 (1)",
>> processor="i386", system="NetBSD/5.1_STABLE", leap=00, stratum=1,
>> precision=-18, rootdelay=0.000, rootdisp=0.315, refid=PPSb,
>> reftime=d2ecad51.c7c9dc25 ?Mon, Feb 20 2012 11:30:25.780,
>> clock=d2ecad57.2e21ead2 ?Mon, Feb 20 2012 11:30:31.180, peer=65276, tc=4,
>> mintc=3, offset=0.000, frequency=-35.663, sys_jitter=0.004,
>> clk_jitter=0.003, clk_wander=0.006, tai=34, leapsec=201207010000,
>> expire=201212280000
>> David

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