Re: [LEAPSECS] GPS versus Galileo

From: Steve Allen <>
Date: Sun, 15 Feb 2004 08:46:15 -0800

On Sun 2004-02-15T12:10:17 +0000, Markus Kuhn hath writ:
> The GPS signal format has been virtually unchanged since prototype
> experiments in the early 1970s

I'm just now reviewing the very recent GPS L2 ICD,%2027Jan2004.pdf

An insignificant difference is the blue-pencilling of
all occurrences of "Universal Coordinated Time" and replacement with
"Coordinated Universal Time.

A significant difference is that there is now a 16-bit field intended
to give the calendar year. This will certainly alleviate any need
to worry about violating the week rollover patent that Tom Van Baak
mentioned a while back.

But I still find no indication that the leap second counters have a
different width. That would leave the GPS receiver implementor with a
need to guess the value of Delta-T to within 256 seconds. Fortunately
that will be a relatively robust guess for many, many centuries.

Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064      Voice: +1 831 459 3046
PGP: 1024/E46978C5   F6 78 D1 10 62 94 8F 2E    49 89 0E FE 26 B4 14 93
Received on Sun Feb 15 2004 - 08:46:26 PST

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