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Re: GPS shortcomings.
From: Richard B. Langley
Date: 2005 Jun 8, 16:52 -0300
From: Richard B. Langley
Date: 2005 Jun 8, 16:52 -0300
GPS IS monitored for integrity but by WAAS! The problem WAS detected by WAAS and the offending satellite was marked as "do not use." Consequently WAAS users were protected from this anomaly. -- Richard Langley Professor of Geodesy and Precision Navigation Fellow of The Institute of Navigation On Wed, 8 Jun 2005, Lu Abel wrote: >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@huxtable.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. >> ================================================================ >> >> > =============================================================================== 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/ ===============================================================================