On 16/08/2013 13:02, John Hasler wrote:
David Taylor writes:
A pity that they haven't been able to find two or three spare bits to
reduce the 1024 week ambiguity to nearer a half-century or even 100
years.
From the Wikipedia article:
To determine the current Gregorian date, a GPS receiver must be
provided with the approximate date (to within 3,584 days) to correctly
translate the GPS date signal. To address this concern the modernized
GPS navigation message uses a 13-bit field that only repeats every
8,192 weeks (157 years), thus lasting until the year 2137 (157 years
after GPS week zero).
Oh, that /is/ good news, John! Many thanks. I couldn't see that from a
quick scan of the referenced documents, so that's most helpful to know.
I wonder whether there is any way to determine which satellites are
sending this modernised message, perhaps they all do, or whether a
particular receiver is using the full 13-bit field? It's something I've
not seen listed in various specifications I've read, but perhaps it's
taken for granted after a certain date?
--
Cheers,
David
Web: http://www.satsignal.eu
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