[talk-ph] Cringely on the GPS network

Jim Morgan jim at datalude.com
Wed May 27 11:21:55 BST 2009


I've been reading this guy's columns for probably about 10 years. He's normally talking about the likes of Apple, IBM and the business of the Internet. And he's smart as a whip. However here he takes on GPS networks. I thought some of you might be interested. 

Jim

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WAAS Up?

The Government Accountability Office, a Federal watchdog agency, reported on May 7th that the Global Positioning System of satellites used for navigation and many other business and scientific purposes as well as for proving that your teenage son was actually driving down the Interstate at 100 miles-per-hour last Thursday night when he claimed to be bowling, well that satellite system is in danger of becoming unusable because satellites are not being replaced quickly enough by the U.S. Air Force.

Only it isn’t true.

Right now on Google News you can find more than 400 stories all saying the same thing with varying degrees of alarm.  The Air Force is three years late in launching a new generation of GPS satellites.  The replacement program is over-budget by more than $700 million.  The whole mess has been incompetently run and ought to be fixed.  All this is true.  What isn’t true is that it matters very much to the real world operation of the GPS system or its users.

The GPS system has 31 satellites in orbit right now, the oldest of which has been operating since 1990.  For the system to work perfectly it must have 24 or more satellites functioning.  The GAO says it is only 80 percent certain that the Air Force can maintain full coverage before replacement satellites can be launched.  This lack of confidence is not based strictly on the idea that eight or more satellites will go dark over the next couple years, but that some undetermined number of satellites will go dark, the Air Force will make no progress in replacing them, and that the remaining satellites will be unable, for some reason, to be moved into new positions, filling gaps in coverage.  That’s quite a combination of improbable events and makes me very suspicious of the 80 percent number.

Continues:  http://www.cringely.com/2009/05/waas-up/






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