Correct me if I’m wrong, but wasn’t the GPS system actually descrambled for the first time during the Gulf War? The situation, as I understand it, was that there were not enough military-grade receivers available to put them to the uses the military wanted, so the signals were descrambled and the troops issued civilian units. The military was relying on economic barriers to keep the enemy from obtaining similar capabilities.
It’s only in the past couple of years that “descrambled” has been the normal state of affairs for the GPS system.
Chronos, you’re a bit incorrect, if I understand you correctly. Having played a teeny part in GPS development, I can tell you that the NAV portion of the GPS system is little more than a good radio transmitter and a very accurate clock. All of the geolocation is done in the ground portion, including your handheld receiver. Each bird knows precisely where it is, and transmits ephemeris and transmit time data to ground processors. Using an algorithm called TDOA (Time Difference of Arrival), the terrestial unit computes the time lag of simultaneous signals from 3 or more birds (4 or more, if you want altitude, or greater accuracy) to compute location in a process similar to triangulation on a 2-d map.
BTW, Selective Availability is the term used by USAF to describe the intentional munging of system accuracy. With SA, a random error is added to the time accuracy to reduce positional precision.
In terms of US resistance to an EU GPS, I would suppose that socioeconomic concerns are important, as discussed elsewhere in this thread. Another concern would likely be what we might call “slot availability.” Believe it or not, LEO (low-earth orbit) space, particularly in the sun-synchronous orbit of GPS birds, is getting crowded, although not to the degree of geosynch. There are only so many “empty” slots, and crowding adds additional safety issues.