Re: [LEAPSECS] The real problem with leap seconds

From: Poul-Henning Kamp <phk_at_phk.freebsd.dk>
Date: Sun, 08 Jan 2006 17:09:37 +0100

In message <20060108154842.GB2665_at_ucolick.org>, Steve Allen writes:
>On Sat 2006-01-07T21:20:33 +0100, Poul-Henning Kamp hath writ:
>> Well, the BIPM doesn't really want anybody to use TAI, their director
>> said as much last year
>
>The Italian contribution to the November 2005 WP7A meeting could be
>interpreted a suggestion that the international agencies in charge of
>time scales need to get their heads together, pick one time scale with
>no discontinuities, and abolish all others.

That sounds like the sensible partys platform to me.

Doing so would once and for all have to divorce earth orientation
from that unified time scale, leaving it to governments to align
civil time with daylight as they see fit (just like today).

>Klepczynski had implied that more clearly on pages 322 and 323 of
>http://tycho.usno.navy.mil/ptti/ptti2004/panel.pdf
>where he discusses getting all the satellite navigation systems
>to use a single time scale.

It is the time scale that is the issue, it's the clock offset between
the systems.

If you have 2 GPS sats, one GLONASS and one GALILEO, you also need
to know the clock offsets between the three systems before you can
calculate a position.

If everybody gets their act together and hold the clock offsets small,
then it would be a wonderful world indeed, but I think the practical,
organizational and political problems will prevent that.

The other option is for the systems to broadcast their clock offsets
relative to the other systems. For that to help rapid first fix
it must be a frequent broadcast (ie: non-almanac) otherwise you
might as well just wait until you get four birds in one system.

>(And to see that psychology is not just relevant to astronomers,
>read Matsakis on page 336.)

Yes, astronomers have psychology too, but the comments on that page
has nothing to do with leap seconds at all.

--
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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FreeBSD committer       | BSD since 4.3-tahoe
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Received on Sun Jan 08 2006 - 08:20:28 PST

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