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    Re: GPS Accuracy Now.
    From: Ed Falk
    Date: 2000 May 03, 1:51 PM

    > > The FAA has been landing a test 727 automatically for a
    > > couple of years, trying out various schemes. Among these is
    > > the use of a pseudolite embedded in the runway, as well as
    > > ground clearance radar.
    That's the work of grad student at Stanford I met.  "pseudolite" is
    short for "pseudo satellite".  A transmitter that generates the same
    kind of signal as a GPS satellite is placed at the airport.  It's used
    somehow to find the phase angle of the data stream relative to the
    satellite carrier wave.
    The FAA (or was it the air force?) rented a 727 for this guy for almost
    a year.  They made 110 landings using his system and he never got to
    sit in the cockpit once the whole time because he was always in the
    back tending the computer.  They only had to take over from the
    computer twice the whole time (once because one of the satellites chose
    that moment to reboot itself.)
    Cute story:  his computer was one of the P90's with the bug in the
    divide circuit.  When Intel was being stubborn about replacing these,
    they said that they'd replace the chips only if you had a real reason
    to need a replacement.  He wrote to them and said basicly, "I am the
    poster child for this bug".  He got no argument from Intel.
            -ed falk

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