On Thu, 12 Mar 2015 18:50:56 -0700, Tom Van Baak wrote: > > I didn't think that NTP or POSIX or PTP is what we'd call a timescale.
As discussed in other responses, a timescale requires only three things, a definition of zero time (or a specified time), a definition of the "second" (or some other time duration unit), and a progression rule. That's it. By this definition, all three (NTP, POSIX, PTP) define private timescales for their own internal use, and translate to and from external timescales as needed. > NTP is a UTC synchronization algorithm. NTP is a synchronization algorithm for sure, but NTP is not limited to UTC, even though the RFCs speak of UTC. Lots of people use NTP to distribute GPS System Time, and I bet that there are people now using NTP to distribute TAI. > UT0 is a measurement. UT1 is a timescale. TAI is a timescale. UTC is a timescale. UT0 *is* a timescale, one that is tied to a specific astronomical observatory. Multiple UT0 timescales are combined to yield UT1, and UTC is derived from UT1. Joe Gwinn _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs