[ntp:questions] Re: distance to dcf77 transmitter: how to set the fudge?
ronan at noc.ulcc.ac.uk
Wed Jan 26 18:14:50 UTC 2005
Folkert van Heusden <folkert at vanheusden.com> wrote:
> Am I right that when I want to tell ntpd that it has to take care of the
> distance to the dcf77 transmitter that I have to do that like this?
Yes, something like this -- delay will be more if you're getting skywave
rather than groundwave.
> # DCF77 receiver
> # "Der DCF77 Sender steht in Mainflingen (50 0 Nord, 09 00 Ost), etwa 25 km
> sdstlich von Frankfurt/Main."
> # http://www.maporama.com/
> # Mainflingen: 50 1' 54" , 9 1' 33" 50.0318 , 9.026
> # Gouda/2804 RR: 52 1' 37" , 4 42' 15" 52.0272 , 4.7044
> # http://www.fcc.gov/mb/audio/bickel/distance.html
> # -> 374.766km
> # speed of light: 299 782.458 km/s
> # delay: 1.25012652ms
> server 127.127.8.0 prefer mode 14
> fudge 127.127.8.0 time1 0.00125012652
> I ask this question as suddenly the offset for my DCF receiver sky-rockets:
> remote refid st t when poll reach delay offset
> GENERIC(0) .DCFa. 0 l 77 64 16 0.000 -246.13 11.484 <---
Ah, fudging time1 overrides the default delay in the PARSE driver, which for
mode 14, RAW DCF at 50baud, is 258ms (RAWDCF_BASEDELAY in refclock_parse.c).
Try including that: fudge 127.127.8.0 time1 0.25925012652
or adjust to taste.
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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