[time-nuts] Satellite Glitch Rekindles GPS Concerns

Brooke Clarke brooke at pacific.net
Thu Jun 18 13:00:00 EDT 2009


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
http://www.prc68.com

Mike Monett wrote:
>   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.
> 
>   http://www.networkworld.com/community/node/42767
> 
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