[meteorite-list] OT help, GPS, DOD

[Chris Peterson]

GPS was never shut down during Desert Storm. The accuracy was selectively 
degraded, however (not enough to severely impact most users). Since 
Selective Availability was switched off a few years ago, the government has 
pledged to maintain a pretty high degree of availability and accuracy. This 
was done in large measure to satisfy those who are using the system for 
safety-critical applications, both in the U.S. and abroad. It doesn't look 
good when civilian planes start crashing in Europe because the U.S. is 
fooling around that day in Iraq.

I'm not sure what you mean by a transponder on every satellite. As it 
stands, each satellite sends a unique, unencoded sequence and a unique coded 
sequence. The first is for everyone, the second for authorized users (mostly 
military). But with differential GPS and WAAS now common, the civilian 
channel is practically as accurate as the military.

GPS is not the only player. There is also the Russian GLOSNASS system, and a 
European system that might come on line. There would be little reason for 
the GPS system to stop being open-access. As it stands, it is the only 
completely free system, and as an American (who helps pay for it) I'm happy 
to keep it that way (even if it means a bunch of freeloaders get to use it 
too <g>). GPS is one of the few places where I actually feel my taxes have 
been well spent.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message ----- 
From: "Tom Knudson" <peregrineflier at npgcable.com>
To: "met list" <meteorite-list at meteoritecentral.com>
Sent: Thursday, June 02, 2005 2:01 PM
Subject: [meteorite-list] OT help, GPS, DOD


> Hi List, someone asked me this question, and since the list has so many
> people, who between them knows just about everything, I thought I would 
> ask
> you!
>
> During desert storm, the DOD often shutdown the GPS satellites at various
> times, because Iraq was using them also. The question is: Since we know 
> that
> the DOD and the United States own the satellites, why is it that everyone
> and their dog are allowed to use it as well? Is it because there's no way 
> to
> put a transponder on each satellite? If so why not??
>
> Thanks, Tom
> peregrineflier <><