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    Re: GPS shortcomings.
    From: Lu Abel
    Date: 2005 Jun 8, 12:35 -0700

    George and list:
    
    There's mention of this failure (due to the failure of the atomic clock
    on one of the satellites) in
    www.ion.org/sections/southcalifornia/ lavrakas_civil_gps_monitoring.ppt
    
    I was rather surprised to learn that there is NOT continuous monitoring
    of the GPS system for integrity of its positioning information, given
    that there's a whole new generation of air traffic control that's going
    to be based on GPS...
    
    Lu Abel
    
    George Huxtable wrote:
    > I know that references to GPS are discouraged, if not forbidden, on this
    > list. But I wonder if a note about GPS shortcomings would be more
    > acceptable?
    >
    > I've just received a leaflet from the British Lighthouse authorities,
    > pushing for use of the new Loran-C transmitter at Rugby, England.
    >
    > In which is the statement-
    >
    > "GNSS systems themselves also suffer occasionally from undetected failures;
    > for example, a satellite clock error on 1 January 2004 gave rise to errors
    > in measured positions of up to 45 kilometres in Western Europe for a period
    > of some 3 hours, resulting in onboard navigational failures."
    >
    > I hadn't heard about that event, which sounds rather serious. Is it common
    > knowledge? Can anyone offer further details?
    >
    > It wouldn't have affected me. I would have been by the fireside on that day.
    >
    > George.
    >
    > ================================================================
    > contact George Huxtable by email at george---.u-net.com, by phone at
    > 01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
    > Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    > ================================================================
    >
    >
    
    
    

       
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