As anyone who's tried to use GPS indoors can tell you, global positioning systems have their limitations. For them to work properly, you have to be outdoors and you need a clear view of the sky. If you’re in the military, you also have to be sure that the enemy isn't jamming the satellite signal. For this reason, the US Air Force has awarded Canberra-based firm Locata a “sole source” contract to install a ground-based version of GPS over 2,500 square miles (6,475 sq/km) of the White Sands Missile Range in New Mexico as part of a program to develop a practical supplement to GPS.
Read the full article: LocataNet positioning system designed to work where GPS doesn't