On Wed 2015-04-08T19:02:07 +0000, Paul_Koning@dell.com hath writ:
So here is the puzzle. I would expect WWV, and www.time.gov, to reflect leap seconds. So why would they give me a time that matches, to the second, the POSIX time on my workstation? Does NTP send POSIX seconds since epoch rather than real ones?
NTP effectively sends "mean solar seconds elapsed since epoch", which is another way of saying "elapsed seconds not counting leap seconds" as is demanded by POSIX. The value of the time in WWV and www.time.gov is conforming to ITU-R TF.460 where the leap seconds in the radio broadcasts were designated as 23:59:60 in order that the value of SI second markers of UTC closely matches the value of mean solar second markers of UT1. In the radio broadcasts those leap seconds are truly intercalary. There is no way for the value of the time in WWV to indicate the number of times that an intercalary second has been inserted since 1972, nor when they were inserted. Before 1972 there was no way for the value of the time in WWV to indicate the number of leaps of milliseconds, nor the number of times that the duration of the broadcast seconds had been changed, nor the current duration of the broadcast seconds. -- Steve Allen <sla@ucolick.org> WGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m