NTPsec flags my GPS as a falseticker

Gary E. Miller gem at rellim.com
Thu Mar 19 22:38:30 UTC 2020

Yo Nick!

On Thu, 19 Mar 2020 22:30:57 +0000
Nick Burkitt via users <users at ntpsec.org> wrote:

> Even if I stop gpsd, which kills both shared-memory segments, and
> reduce my ntp.conf file to this:
> refclock shm unit 0 refid GPS
> I still see this error (in stdout, since there's no log file):
> 2020-03-19T22:13:50 ntpd[23312]: CONFIG: configpeers: Ignoring
> duplicate ''

Then something is very wrong.  Grab the source and build your own
ntpd to see if this goes away.

> Is it possible to define a reference clock (using the refclock
> command) without provoking this error?

Better question: howcum no one else can force this error?

> Nothing unusual in /etc/ntp.d:

How can you tell from a directory listing?  Remove all that and

> >There is probably a way to tell gpsd how to find the PPS device.  My
> >guess  
> I believe the official method is to include it on the command line.
> :-)

At least in the case of a Raspberry Pi.

> >
> >would be that it looks for /dev/pps0 when it opens the first serial
> >port and uses if if it finds one, else does the ldattach dance to
> >make it.  
> gpsd doesn't find /dev/pps0 unless I specify it on the command line.

Incorrect.  If the pps is associated with a serial port it is
automagically found.

> >That's the mindist stuff in my second message.  I forgot to include
> >this line from my ntp.conf
> >
> >tos mindist 0.250                      # default is 0.001 (1 ms)  
> And that seems to be the magic incantation that has been missing from
> my ntp.conf until now!
> 250 ms is probably more generous than I need - I don't see offsets 
> greater than about 15 ms, but it probably doesn't hurt
> I think the mystery is finally solved!

Really?  That just raises a new one.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin
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