[ntp:questions] Maximum time2 fudge value for NMEA refclock?

David J Taylor david-taylor at blueyonder.co.uk.invalid
Fri Jul 16 13:45:40 UTC 2010


"jimmyterrence" <jimmyterrence at gmail.com> wrote in message 
news:1c01938f-d43e-4dea-a143-45e096d318fd at j8g2000yqd.googlegroups.com...
[]
> If it was triggering on the wrong edge of the pps signal, wouldn't it
> be off of the rest of the servers by the length of the pulse? I think
> that it's triggering properly.

Agreed.

> My 555 ms fudge, from the config file.
>
> #gpsd PPS
> server 127.127.28.1 minpoll 4 maxpoll 4 prefer
> fudge 127.127.28.1 refid PPS
> #gpsd
> server 127.127.28.0 minpoll 4 maxpoll 4
> fudge 127.127.28.0 refid NMEA flag4 1 time1 0.555
>
> I stopped gpsd to check and make sure I had set the outputs properly,
> but it shows just one sentence, GPRMC.
>
> $GPRMC,130803,A,4416.2422,N,07823.4033,W,000.0,143.4,160710,011.6,W*71

I thought that the NMEA driver just needed to be to the nearest second 
when you had a PPS signal?  As you have good Internet servers, there may 
not even be a need for the NMEA driver at all (at least with recent 
versions of PPS, but I'm outside my scope of knowledge here).  I run 
FreeBSD, ntpd 4.2.4p5-a (1),  and my configuration file has:

server  127.127.20.1    mode 0  minpoll 4 maxpoll 4  prefer
fudge   127.127.20.1    flag1 1 flag3 1 refid PPS

The PPS is built into the type 20 driver.  Pity you can't use that.

Cheers,
David 




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