[time-nuts] Satellite Glitch Rekindles GPS Concerns

Mike Monett xde-l2g3 at myamail.com
Thu Jun 18 13:40:43 EDT 2009


  > Hi Mike:

  > The current  issue of Inside GNSS has two articles about  this and
  > their web page has a new article dated 17 June 2009.

  > http://www.insidegnss.com/

  > Hi again Mike:

  > The IIR-2  satellite  was  launched in order  to  meet  a deadline
  > rather than when it was truly fully operational. The L5  module is
  > an add  on  and  can  not run at full  power.  So  this  is  not a
  > representative of the future sats.

  > Have Fun,

  > Brooke Clarke

  Running at full power would make the problem worse, don't you think?

  This slipped past all the modeling and simulations prior  to launch,
  so as  well  as fixing the problem, they also  have  to  improve the
  simulations. Somehow  that  doesn't   seem   like  such  a difficult
  problem.

  Overall, I  think  they  did a pretty good job  for  such  a complex
  system with such incredibly tight performance parameters.

  At least  it still works, with degraded accuracy. And it  looks like
  they can fix it. So it's not like sending a billion-dollar satellite
  to Mars  and  having  it crash  because  someone  forgot  to convert
  between US and metric values:)

  Hopefully the L5 addition will help reduce the diurnal  variation in
  ionosphere delays that affect the accuracy of the timing signals. So
  progess in this area is of interest to us.

  And thanks for the link to insidegnss. That looks like  an excellent
  resource for updates on the technology.

  Mike




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