Re: [LEAPSECS] An immodest proposal

From: M. Warner Losh <imp_at_BSDIMP.COM>
Date: Tue, 14 Feb 2006 14:28:34 -0700 (MST)

In message: <6BB0D094-0707-458D-B804-D172DA182EAF_at_noao.edu>
            Rob Seaman <seaman_at_noao.edu> writes:
: On Feb 14, 2006, at 12:50 PM, Markus Kuhn wrote:
:
: > You can, of course, define, publish, implement, and promote a new
: > version (4?) of NTP that can also diseminate TAI, EOPs, leap-second
: > tables, and other good things. I'm all for it.
:
: But why are you for it? Before investing large amounts of time and
: money in developing and deploying a large new timekeeping system,
: wouldn't one want to invest smaller amounts in exploring the issues
: and options? Heck - one has to imagine that a number of successful
: grant applications are lurking around here somewhere. Time is an
: issue that cuts across every funding agency out there.

UTC time stamps in NTP are ambiguous. TAI ones are not. UTC time
stamps do not convey enough information to properly implement things
like intervals, while TAI ones do. The NTPNG stuff that I've seen
appears to consider these problems as worthy of needing a solution and
they plan on solving them. It isn't rocket science, but one has to
divorce ones self from the chauvinistic view that UTC is always best.
For time exchange, it is not the best, and has many problems around
the edges.

Doing NTP with TAI (and the implied requirement for DTAI) doesn't
change what time is displayed for users. It does make it *MUCH*
easier to get leap seconds right for those users that need them.
Anything else is madness. UTC is a display convention, not a sane[*]
counting convention.

Warner

[*] All variable radix counting conventions are insane by (my humble)
definition :-).
Received on Tue Feb 14 2006 - 13:29:12 PST