[time-nuts] Satellite Glitch Rekindles GPS Concerns

Mike Monett xde-l2g3 at myamail.com
Thu Jun 18 09:41:06 EDT 2009

  An article in NetWork World discusses performance degredation in the
  new Lockheed-built  GPS  IIR-2  satellite.  Apparently.  the  new L5
  transmissions are interfering with other signals from the satellite.

  This reduces  the accuracy an order of magnitude, from 2 feet  to 20
  feet. It  should have a corresponding effect on the accuracy  of the
  decoded time signals.

  The Air  Force said it has identified several parameters in  the GPS
  IIR-20 (M)'s  navigation  message  that   can  be  corrected  and is
  studying the impact these may have on military and civil GPS users.

  Presumably, the  problem  will  be corrected in  the  12  Boeing GPS
  satellites currently being built that also feature the L5 signal.

  The article  discusses  issues   such   as  delays  due  to techical
  problems, cost overruns, and aging of the fleet. These  could affect
  system performance in the future.

  However, Col. Dave Buckman stated

  "The issue  is  under control. We are working hard  to  get  out the
  word. The issue is not whether GPS will stop working. There's only a
  small risk we will not continue to exceed our performance standard,"
  he said.


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