[ntp:questions] Re: Arcron DCF77 ref clock driver: problem with timezone and UTC

Ronan Flood ronan at noc.ulcc.ac.uk
Mon Mar 21 14:24:53 UTC 2005


"Eric Voisard" <evoisard at MAPS.ON.ieee.org> wrote:

> Well, it works, serial connection with the device is established and ntpd
> apparently gets the time which I can see on the small LCD display of the
> receiver, however after a while ntpd complains about too large an offset and
> stops.
> 
> What I can see is that this offset is around 3600 seconds, what corresponds
> to GMT+1, the local shift in my country...
> 
> However, the computer is set to work in GMT time. The /etc/TIMEZONE file is
> set accordingly and the "date" and "date -u" commands give same time, so
> it's ok.
> 
> The receiver's LCD display indeed shows the local time (GMT+1), but its
> specs say that a driver can query the time in UTC. On its side, the type 27
> refclock driver says that by default it queries the time in UTC (as it
> should do anyway since ntpd only works with UTC times). And in addition it
> provides the fudge parameter "flag1" to toggle between UTC and local time.
> 
> I tried to play with this "flag1" parameter, but it makes no difference:
> ntpd keeps complaining about this 1 hour offset. The type 27 driver seems
> mistaking the local time for the UTC one...

Does the receiver spec say how to query it for UTC?  It might provide
the same time as it displays, which you say is GMT+1, unless specially
requested.  Can you set the display to UTC/GMT?  That might make it
provide UTC to the serial line.  Daylight-saving could become an added
complication.

I think the flag1 fudge depends on your TIMEZONE being correctly set
(it uses mktime), which if you have GMT set could be confusing it.

-- 
                      Ronan Flood <R.Flood at noc.ulcc.ac.uk>
                        working for but not speaking for
             Network Services, University of London Computer Centre
     (which means: don't bother ULCC if I've said something you don't like)



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