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    Re: GPS as a time authority
    From: Richard B. Langley
    Date: 2009 Sep 16, 09:21 -0300

    The message type you mention below has not yet come into effect. It is part of the CNAV
    message structure to be used in the future by GPS satellites. No satellites are
    currently transmitting CNAV data. But, by the time of the next rollover (2019), they
    will be so we shouldn't have the problem we had during the previous rollover.
    -- Richard
    Quoting Smith_Peter@emc.com:
    > On Tuesday, September 15, 2009 2:55 PM, Richard B. Langley 
    > said:
    > > No it isn't. The receiver must keep track of rollovers by itself. More
    > info here:
    > > .
    > > -- Richard Langley
    > >
    > > Quoting Smith_Peter@emc.com:
    > >
    > >> The number of roll-overs is included in the  GPS message stream
    > Actually, since your (very interesting, by the way) article was written
    > in 1998, the GPS message stream has been beefed up to include, among
    > other data, a 13-bit Extended Week Number or Transmission Week Number
    > (not exactly a count of roll-overs -- I misspoke). This field is in
    > message type 10, bits 39-51. See NAVSTAR GLOBAL POSITIONING SYSTEM
    > INTERFACE SPECIFICATION, IS-GPS-200, 7 March 2006 at
    > https://navcen.uscg.gov/gps/modernization/IS-GPS-200D_w_IRN_1_7Mar06%20N
    > S.pdf
    >  -- Peter Smith
    > >
     Richard B. Langley                            E-mail: lang@unb.ca
     Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/
     Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506 453-5142
     University of New Brunswick                   Fax:      +1 506 453-4943
     Fredericton, N.B., Canada  E3B 5A3
         Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
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