[ntp:questions] using both a PPS source and a HBG (dcf-77-like) timesource?

Unruh unruh-spam at physics.ubc.ca
Sun Jan 13 17:35:10 UTC 2008

folkert at vanheusden.com (Folkert van Heusden) writes:


>To my pc I have connected a garmin 18lvc and a HBG radio clock receiver.
>Now what I would like to do is:
>- let the hbg receiver set the current time and when the HBG signal is
>  not available (bad reception or the 59 seconds while it is receiving
>  the broadcastmessage) use the PPS signal of the garmin for the PPS(!
>  not the time, only the PPS)

Why would you do that? I can see using the radio clock initially to sync
the clock approximately to the real time, but the GPS pps is almost
certainly much more accurate. The radio receiver will be late by of the
order of millisec, while the gps will be "on time" to microseconds.
Of course you may not care, but someone who has two onboard time sources
would care, I would think.

>I read that for this I need to set:

>(my reference clock)
># GUDE expertMouseClock HBG receiver 

>server mode 14 prefer
>fudge refid HBG

># use PPS signal from Garmin 18 LVC
>server minpoll 4 maxpoll 4
>fudge flag flag2 1

>Is this the correct way? How can I verify that it is using the PPS
>Am I right that it currently does not work?
>Because it says noreply == poll:
>belle:/home/folkert# ntpq -c clockvar
>assID=0 status=0101 clk_noreply, last_clk_noreply,
>device="PPS Clock Discipline", timecode=, poll=11, noreply=11,
>badformat=0, baddata=0, fudgetime1=0.000, stratum=16, refid=80.80

How do you have the 18lvm connected to your system?

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