Global Positioning Experiments (GPX)

The GPX program helps solve the GPS jamming threat problem. DARPA's approach is to solve the problem of GPS jamming by developing airborne pseudo-satellites (or "pseudolites") which provide high power GPS signals that overpower the jammers. A pseudolite system can be thought of as being a miniature GPS constellation. Four pseudolites are required for a full navigation solution, just as four GPS satellites are required today. The airborne pseudolites would find their own position from GPS satellites, even in the presence of jamming, through the use of advanced beamforming anti-jam antenna systems.