[ntp:questions] Start of new GPS 1024 week epoch

David Taylor david-taylor at blueyonder.co.uk.invalid
Fri Aug 16 13:34:34 UTC 2013

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?
Web: http://www.satsignal.eu

More information about the questions mailing list