> > I've heard that NTP acts funny when it tries to sync over an ADSL > > line. > > That seems to be the case indeed: > [] > > And there it is: 20ms offset. From what I've heard this is caused by > > ADSL being asymetric. > > Now I was wondering, can't this be fixed by telling the NTP daemon how > > much asynchronous the line is? I mean: it can be easily measured what > > the down- and upload bandwidth is. > > Have you measured and removed the delay for the DCF77 device? There > receiver bandwidth will cause a delay, as will the propagation delay of > the radio signal.
Well if I look in the comments of my ntp.conf it seems I looked into that a while ago: # DCF77 receiver # "Der DCF77 Sender steht in Mainflingen (50 0 Nord, 09 00 Ost), etwa 25 # km südöstlich 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 # 1.25012652ms delay so I need to add an offset of 1.25ms somehow? still less then this 17ms offset I saw. # mode 14, RAW DCF at 50baud, is 258ms (RAWDCF_BASEDELAY in refclock_parse.c) Do I also need to add an extra offset of 258ms since it takes the first bit at least 258ms to get in? Folkert van Heusden -- www.vanheusden.com/recoverdm/ - got an unreadable cd with scratches? recoverdm might help you recovering data -------------------------------------------------------------------- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
