Re: WAAS satellite ( INMARSAT 3-F4 ) moving Feb 1, to 142 degrees West

From: Jim King (
Date: Tue Jan 31 2006 - 13:49:52 EST

  • Next message: tony dinkel: "Re: WAAS satellite ( INMARSAT 3-F4 ) moving Feb 1, to 142 degrees West"

    The GPS ephemeris is broadcast as part of the GPS data stream. GPS 
    satellites change orbits, as well as having old satellites retire and 
    new satellites activated. A GPS receiver with a fixed pre-programmed 
    ephemeris wouldn't be useful for very long, if at all.
    Jim wrote:
    > Kevin said (in part),
    > "INMARSAT 3-F4 ( 24819) currently at 54 degrees West, is been moved to 142 
    > degrees West. This satellite is part of the WAAS system, which is used to 
    > broadcast correction data to GPS users. It will be fun to watch it move on, the 
    > GPS receiver display.
    > Kevin and others,
    > I thought that the position of the satellites as marked on the GPSr display was 
    > taken from an ephemeris that was programmed into the GPS receiver by the maker 
    > of the unit. If it is than the WAAS should not move in the display. If the data 
    > is modified by what the satellite sends out then it should.
    > Anybody know for sure about this?
    > Tom  Iowa  USA 
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