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    Re: GPS as a time authority
    From: Lu Abel
    Date: 2009 Sep 15, 09:52 -0700

    Most GPS receivers are, however, aware of the difference between "GPS 
    time" and UT1 and automatically correct for it in their display.   If 
    one digs down down into the setup parameters in the average GPS receiver 
    one will find a choice of time displays, including both GPS time and 
    UT1.   The factory default setting is usually UT1, since that is the 
    time we all live by.
    But you do raise an interesting point -- is it possible that the time 
    difference observed by the original poster, John Parsons, was due to 
    someone having their GPS set to display GPS time rather than UT1???
    Lu Abel
    antoine.m.couette@club-internet.fr wrote:
    > I think that the reason brought up by "M. Lunav" is quite valid : processing 
    times may vary according to types of GPS receivers.
    > There is also an ESSENTIAL REASON, which may have been skipped in this thread.
    > GPS cannot accomodate any time discontinuities. Therefore, some 15 years 
    ago, GPS time - i.e. the one used by the GPS System - was the same as UT1.
    > Now with the extra seconds added now and then to take in account the Earth 
    rotation changes, GPS time itself which is much more stable than UT1 has 
    become different from UT1 by a number of seconds amounting to 8 seconds (this 
    amount to be confirmed) to-day.
    > Antoine M. Cou?tte
    > >
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