Re: [LEAPSECS] A lurker surfaces

From: Poul-Henning Kamp <>
Date: Wed, 03 Jan 2007 10:24:30 +0000

In message <>, Zefram writes:

>Would have been nice. Actually, since the only real significance of
>GPS time is that it's part of the signal format, they could just as
>well have picked an unconventional but space-efficient encoding (say,
>32-bit count of seconds, wrapping every 4 Gis). I think GPS time is
>best viewed as an encoding of TAI(GPS).

I have been told by a person who should know better than to tell
me such things that the choice of timescale in GPS "is the result
of unmitigated incompetence and the signal format is sheer stupidity".

The fact that the UTC offset is in the Almanac instead of the
Ephemeris means that almost all of the rapid response weapons cannot
be used for tightly timed attacks until they have been primed with
an almanac.

He talked about the transmissions of the almanac being staggered
between the satellites rather than in tandem, to reduce the mean-time
to capture UTC-delta, but I did not find out if this was reality
or plan.

I guess one could use the "raw-dump" message to the Oncore and
decode the almanac by hand to find out if this is the case.

He also said that the quote in my .signature was used more often
in Pentagon than he was comfortable with.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk_at_FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Received on Wed Jan 03 2007 - 02:34:55 PST

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