David, David J Taylor wrote: > David L. Mills wrote: >> David, >> >> In the NTPv3 spec the leap bits are to be set on the day of the leap. >> This is compliant with the new NTPv4 spec; that spec is more liberal >> in order to support and prioritize leap warnings when multiple means >> are available. In cases where the radio delivers a timecode via >> serial port, some radios include provisions for leap warning; some do >> not. I don't know if an NMEA sentence has provisions for that. There >> are no provisions for leap warning in IRIG devices I have. >> >> I don't know if the Meinberg GPS or EndRun CDMA receiver include >> provisions for leap warning. If so, it should appear in the NTP header >> on the day of the leap. Both receivers use an embedded Linux system >> which in principle has the same provisions as the public >> distribution..
Dave, please see my other reply or http://www.meinberg.de/english/info/ntp.htm to see how Meinberg devices work. > Thanks, Dave. I don't know about the NMEA sentence either, but I don't > recall seeing that possibility. On my GPS-based server, it does also have > Internet sources, but even though one of those sources is showing the leap > bit, my server is not. I'm not sure about this, but maybe it depends on the classification of an upstream server (whether it is in the surving group of ppeers after the selection algorithm) whether the leap second announcement is accepted, or not. > I'll have to check on December 31st. It will be > disappinting if I have similar problems to last time! > > http://www.satsignal.eu/ntp/ntp-events.htm#leapsecond > > In view of the popularity of the GPS18-LVC it's a pity that the driver > support for the leap second isn't better, but I appreciate that being able > to test once every few years doesn't make things any easier! There is a complete chain which needs to be able to propagate the announcement of a leap second. - From the GPS satellites to the receiver - The receiver must output a time string format which supports leap second announcements, and must set the announcement correctly - NTP's driver for that device must evaluate the announcement in the string correctly and pass it on to the NTP kernel If you are not sure whether the whole chain you're using supports leap second announcements correctly you should install and use the NIST leap second file on your server(s). If you discuss ways to announce leap seconds you also have to distinguis the *way* leap seconds are announced. E.g. both the GPS satellites and the NIST leap second file do not only announce an upcoming leap second, they also contain information *when* the leap second will occur, so unless there is a software bug which does the evaluation wrong you could start to announce the leap second as soon as the IERS has published this. If there's just an announcement flag (like the leap bit in the NTP packet) that bit should should not be set until the moment of leap second insertion is unambiguous. Martin -- Martin Burnicki Meinberg Funkuhren Bad Pyrmont Germany _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
