Passive ranging of an airborne emitter by a single non-maneuvering or stationary sensor

A method for passively determining the range of a target vehicle relative to a non-cooperating moving test platform is disclosed. The method includes the steps of moving the test platform along a single linear path at a constant speed, while simultaneously performing a succession of bearing and frequency measurements on a radiant signal emitted by the moving target vehicle. Similarly, the test platform may remain stationary so that its velocity is zero. The measured parameters, along with knowledge of the test platform's own position and velocity, permit the range to the emitter, its velocity and its transmitted frequency to be determined.