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

David J Taylor david-taylor at blueyonder.co.uk.invalid
Fri Jul 16 05:56:19 UTC 2010

> Is there a maximum fudge value above which the NMEA refclock throws
> away input? Both my 18xLVC GPS receivers output serial data about 550
> ms after the PPS signal. That works fine with gpsd, but I've been
> trying to set up the NMEA driver with pps compiled in the 2.6.34
> kernel and it doesn't seem to work.I thought I read somewhere that it
> accepts a max of 400 ms but I can't seem to find that anywhere. Could
> anybody tell me what the value is, and maybe point me to the line in
> refclock_nmea.c (if that's where it is) that governs that?
> Thank you,
> Court


This site suggests nearer 350ms than 550ms:


Are you using the minimum sentences, and the right edge of the PPS signal? 
I have no such problems with a GPS18x LVC on Windows with ntpd 
4.2.6p2-RC5-o, but I haven't tried it on FreeBSD which still runs my GPS18 


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