[ntp:questions] PPS signal from Garmin GPS 18x LVC
david-taylor at blueyonder.co.uk.invalid
Mon Dec 30 11:17:01 UTC 2013
On 29/12/2013 23:51, Adrian P wrote:
> Now I am wondering if there is any other way to see if the PPS signal
> is used or not... maybe with some debugging?
Does the ppstest work? That shows whether the hardware is connecting
properly, and that PPS support is present. Yes, I see from your earlier
post that it does work. But try ppstest as ppswatch - see how close the
the second edge you are.
If so, what are the relevant lines in your ntp.conf?
You should be seeing one line of output from ntpq -pn for each of the
configured servers. However, checking on my FreeBSD system shows that
the NMEA driver can produce PPS sync directly, without having to add the
I see that you have:
server 127.127.20.0 mode 1 minpoll 4 maxpoll 4 prefer
fudge 127.127.20.0 flag1 1 flag2 0 flag3 1 refid PPS
server 127.127.20.1 mode 0 minpoll 4 maxpoll 4 prefer
fudge 127.127.20.1 flag1 1 flag3 1 refid PPS
I'm not sure whether it matters which sentence you choose to process -
it seems that I'm using mode 0 - $GPMRC. I would see whether altering
flag3 to 0 makes any difference, as there was a discussion about the
polarity of that flag.
Just a few things which you can try easily.
Yes, ntpd can be run with debugging, but that's rather outside my expertise.
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