Have come across requirements in MIL sat comms systems that need GPS time as well as UTC. In fact I supplied a system to a MIL customer a few years ago with two Zyfer GPS NTP servers - one set to provide UTC time and the other set to provide GPS time.
Rob Kimberley "David L. Mills" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > Joseph, > > Please say what GPS equipment is used in the "big radar world" to deliver > TAI or even GPS. My expensive GPS receivers have no provision for other > than UTC. TAI is of course a constant offset from GPS give or take > laboratory nanoseconds. It would be interesting to learn why big radar > needs other than UTC. > > Dave > > Joseph Gwinn wrote: >> Dave, >> >> In article <[EMAIL PROTECTED]>, >> "David L. Mills" <[EMAIL PROTECTED]> wrote: >> >> >>>Joseph, >>> >>>Conversely, if a client syncrhonizes to a server strictly running TAI and >>>never signals leaps, NTP will deliver TAI. NIST, USNO and I have >>>discussed this serveral times and concluded the lessor of two evils is to >>>continue with NTP on UTC. >> >> >> Yep. True enough. But GPS emits TAI (plus an offset), so one can claim >> that configuring the NTP timeserver to emit GPS System Time (not UTC) is >> to generate what is essentially TAI. This is widely done in the >> big-radar world. >> >> Joe >> >> >> >>>Dave >>> >>>Joseph Gwinn wrote: >>> >>> >>>>In article <[EMAIL PROTECTED]>, >>>> [EMAIL PROTECTED] (David Woolley) wrote: >>>> >>>> >>>> >>>>>In article <[EMAIL PROTECTED]>, >>>>>[EMAIL PROTECTED] wrote: >>>>> >>>>> >>>>> >>>>>>compliant. Is there a similar mod for NTP. I am >>>>>>hoping that there is a mod that will cause NTP to >>>>>>supply theoretical UTC (even if it is not ascci). >>>>> >>>>>Both POSIX and NTP use UTC. Your problem is that you are not using >>>>>using UTC, but, rather, using TAI. >>>> >>>> >>>>Actually, POSIX does *not* use UTC in the normal sense of the word, as >>>>no leap seconds are applied. >>>> >>>>The fundamental POSIX timescale counts what amount to SI seconds from >>>>the POSIX Epoch, 0h 0m 0s UTC 1 January 1970. Every day contains >>>>exactly 86,400 seconds. >>>> >>>>That said, if one drives a POSIX box via NTP from a GPS timeserver set >>>>to emit UTC (versus GPS System Time), time on the POSIX box will be >>>>pretty close to UTC. >>>> >>>>Joe Gwinn _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
