[ntp:questions] DCF77 Problem

Rob nomail at example.com
Wed Feb 25 18:07:47 UTC 2009

Rob van der Putten <rob at sput.nl> wrote:
> Hi there
> Rob van der Putten wrote:
>> sput:~# stty -a </dev/refclock-0
>> speed 50 baud; rows 0; columns 0; line = 0;
> At 50 baud 9 bits (start + 8 data) is 180 ms. The max pulse length is 
> just under 200 ms, so there is no stopbit. Is this OK? Should I build a 
> circuit to reduce the max pulse length?

No you should not touch the pulse length, it conveys the time information.
50 baud is the correct setting for the port.

> <Cut>
> Is it possible that interference confuses NTPD in a way that it can't 
> recover from? It this a bug?

There have been various problems in the parse driver that cause things
like trash being written to the logfile, ntpd exiting on bad input, etc.
It will depend on the version of ntpd that you use, if you have any
problems like that.  For some time, I had to run a "watchdog" process
that restarts ntpd when it has crashed.  But lately this has not been
a problem.

It is normal to get things like this in the logfile:
25 Feb 18:50:00 ntpd[4540]: parse: convert_rawdcf: parity check FAILED for "-#-#---##----#----M-S----1-4p---81-p12-8--124--4---2--1---p_"

25 Feb 18:50:00 ntpd[4540]: PARSE receiver #0: FAILED TIMECODE: "-#-#---##----#----M-S----1-4p---81-p12-8--124--4---2--1---p" (check receiver configuration / wiring)

When it happens too often or all the time, you will need to find a better
place for the receiver, or align its direction.

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