[ntp:questions] PARSE refclock for DCF77

Rob nomail at example.com
Thu Mar 12 17:42:45 UTC 2009

Matthias Fuchs <matthias.fuchs at esd-electronics.com> wrote:
> Hi,
> I am experiencing strange issues with the PARSE refclock in mode 5.
> I have a simple DCF77 recevier connected to a serial port.
> In general the refclock works with this setup and ntp syncs.
> Since this simple DCF77 receiver is not very reliable the refclock
> sometimes receives a wrong date/time. This makes ntpd very unhappy.
> Am I right that this refclock driver does nearly no checking
> on the received telegrams? Parity checking is not enough for DCF77.
> Has anybody experience with this reference clock driver and those
> simple DCF77 receivers with NTP?

It depends on the actual version of the software that you use.

I have seen versions that simply crashed when they receive bad DCF77
data, or that exited with some error message about the offset being
too large.  Not good, indeed.

But the version I currently use (4.2.4p5) is not showing any undesirable
behaviour.  It seems to ignore incorrect data as it should.

So what is your problem?

Of course you should add a couple of other sources (say 3 internet time
servers) in addition to your DCF77 refclock.

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