The Global Positioning System, or GPS, enables users on the ground to determine location by connecting to distant satellites using radio signals. The satellites are more than 12,000 miles away from the user and are solar powered, which necessitates a relatively low-powered radio transmission from space, and in turn drives a need for GPS receivers to be very sensitive to the very low-powered signals as received on Earth.
Since the first GPS satellites were launched more than 30 years ago, the system has become a critical and extremely reliable part of our national infrastructure. Billions of dollars in public and private investment in GPS-based technologies and services have produced a steady stream of innovations and helped make the U.S. the global leader in this area. In recognition of the critical nature of this technology, the European Union, Russia and China have all committed to deployment of substantial satellite constellations similar to GPS.