-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 [email protected] wrote: > Am Friday, 7. September 2012, 21:31:56 Martin Burnicki wrote: >> All of the above is correct, and in addition the time derived from the DCF77 >> standard AM modulation is often not very accurate. >> >> Usually there are limited antenna and filter bandwidths to suppress >> electrical noise, and these filters are causing a signal delay which >> results in a time offset depending on the filter bandwith. >> >> One can try to fudge the refclock time such that the resulting offset for >> the refclock is in the range of the offsets observed for the external NTP >> servers, which should prevent the refclock from being overvoted by the NTP >> servers and thus flagged as falseticker. > I am located near Frankfurt, so the distance should not be the problem. Even > in the basement I can receive the DCF77 signal. I played around with the > fudge > time1 parameter. At the moment I have it set to > > server 127.127.8.0 mode 19 > fudge 127.127.8.0 time1 0.009 > > But until now I could not find a good value. > > Thanks for all of your help and your suggestions. > > Regards > _______________________________________________ > pool mailing list > [email protected] > http://lists.ntp.org/listinfo/pool
You need a great circle calculator to calculate the propagation delay between the radio source and your location. This is true for all radio time sources using NTP. On this site... http://williams.best.vwh.net/gccalc.htm ...set the 'distance' to 'km' and the 'Earth model' to 'WGS84/NAD83/GRS80'. Then enter the radio source's location (Lat/Long -- Can be gotten from WikiPedia) and your location. Hit compute. Then take the distance value output and multiple it by 1000 to get it in 'm'. Lastly divide this value by the speed of light in 'm/s' (299792458). This will give you the propagation delay in seconds. Take that value, verbatim, as is and use it for your fudge time offset! <OFFSET/DELAY> = (<DISTANCE IN KM> * 1000) / 299792458 - --Luke -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iQIcBAEBAgAGBQJQSsUqAAoJEMZeNFc/oeKf8q8P/RHKNSgpbP3bXHvauhuTPWgX pu99RqNPmzRi+Cs9kC6pLDQFTRN+SYux4JuM0nFoCcOs2GWc+Uzn/uQBPZltGjO+ RtxLeQPAQO1aUKyrzsTWMNf3ZuoQpqNJqNnbUImSVJ6yIQODQSP7HySiMzzyZjoP u4iO+N3ylEEk4NuSbYiVPWCenkwTngTu7MZ3YAKJb+Z6CH5v6ZASnf5tEi7DZfiT QT9SwA0yVTAZNewRVlTd9j5z8tLKhM4oLxbMMX2pnohoH4F5tnQD1wGcf+5wCAZX usD6tXwIUUsClGcwBY1EdVqXKsHr1d+wt+oiWODNXUskZfvS8RAgQq8s43GDaCn9 Z0OSptrHFWiRDaus3Kn3obvaasIM2Vy3cZd9JH8P6BxGyCPqxBwuLNhhEm+5tXjX Y70ABM5RSKybWM59F2BmG4Glc5rQU9Evt2cwDBwb2FCaGkfAL3vX6lcsdduj76L4 Tx1sUMy0Vrpe8lNMAmiCPLqJAqjcVYXrrYdjhr+fP6LVY1G26+E8ooMVgSXvMrK+ VN79MOa7dmNSN1aXsVAHZGxJA2Eo8Tg9Te2Lv3L4AH7LTO/kVTjfJPYKA/5LWSk2 ttNOP2Jp5+CYBaGniwD/OAUsF86mYeEQpEZPlg7L2t/pvGju0RdwC/MJhyrTG1IL BKTKKSPkxRR/sr1PLyN1 =XQDb -----END PGP SIGNATURE----- _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
