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

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Mon Jan 14 18:50:27 UTC 2008


>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)

In general, ntpd tries to use the best clock.  It normally
does a pretty good job of that.  It isn't setup to read
beteween the lines and do what you think is best.  It gets
that from the raw data with a lot of filtering and heuristics.

I haven't looked at the code for the HBG receiver, but it should
treat each bit as a one second marker, just like a PPS signal.
Yes, it will have to wait until it gets a whole message to get
locked up, but after that it should know the time for each tick.

The refclock driver support code has a 64 slot FIFO and code
to discard outliers so you shouldn't have to worry about the
59 seconds between complete messages.


> server 127.127.22.0 minpoll 4 maxpoll 4
Why are you adding the minpoll/maxpoll?

-- 
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