[ntp:questions] Re: distance to dcf77 transmitter: how to set the fudge?

mike michael.no.spam.cook at wanadoo.fr
Wed Jan 26 22:34:53 UTC 2005


I had the same problem when chosing a delay factor based just on the
straight line calculation. I found that to get the correct delay I had 
to add about 30ms. I suppose that is due to cable/circuitry delays 
though I haven't scoped it.


Folkert van Heusden 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?
> 
> # 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 
> jitter
> ============================================================================== 
> 
>  GENERIC(0)      .DCFa.           0 l   77   64   16    0.000  -246.13  
> 11.484  <---




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