[time-nuts] Health of GPS constellation questioned -- "recently there have been more satellite outages than ever before"

Christopher Hoover ch at murgatroid.com
Tue Sep 5 23:22:36 EDT 2006

[ the story seems overblown to me, but still worth sharing.  follow the
last link for some real data. - ch ]

GPS World: Current GPS constellation
Aug 30, 2006

The current GPS constellation - its health and viability - continues in
question and under scrutiny, despite reassurances from the Air Force. 

Last month's GPS World Survey & Construction e-newsletter relayed user
plaints that there aren't enough healthy GPS satellites. Surveyors say
they can't use RTK a full day with the current constellation even with
every satellite healthy - and that recently there have been more
satellite outages than ever before. They've resorted to filling GPS gaps
with GLONASS. 

The online story drew immediate affirmation. "While most of the time we
get good coverage, for the last couple months we have had a 4 to 6-hour
gap where we 'float' a lot and our precision goes down. Unfortunately
this gap is usually between 10 am and 2 pm, which creates some
interesting scheduling problems." 

For years only three companies offered combined GPS/GLONASS receivers;
that number recently doubled and now includes all major survey
manufacturers. The market speaks. It would be ironic if GPS troubles
helped revive GLONASS, just as perceived GPS shortcomings helped launch

Others have written to ask what the JPO has been doing that has kept
them occupied and unable to carry on GPS modernization or effective
sustainment. In our September print issue of GPS World, We invited the
GPS Joint Program Office to give their view
<http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=368240> ,
and we asked an independent consultant for his perspective
as well.

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