Abstract: A radar system for passive determination of range to a non-cooperative scanning radar, to a non-emitting object illuminated by the scanning emitter and between scanning emitter and illuminated object entirely from the passive location. The radar equipment at the passive location includes a passive array with beam forming and switching matrix to provide output signals separately on the basis of angular discrimination, for each of the object and emitter. Resolver circuits respond to the angle between emitter and object vector, the incremental time between direct emitter reception and reflected echo from the object as well as to emitter scan rate and instantaneous pointing angle. Algorithms for the emitter range, object range and range between emitter and object are given.

Abstract: A passive radar ranging system having an antenna system for receiving radiated electromagnetic energy emanating from an emitter source, plus a translation resolution system and a digital computation system for making phase measurements of the received electromagnetic energy with the translated and resolved energy signals being operated upon by a plurality of system spacing parameters, the radiated energy being modulated in a particular pattern, randomly modulated or unmodulated and with the emitter source being fixed or moving while the phase measurements are made from a single measurement platform which may also be fixed or moving with respect to the emitter source, the phase measurements being employed for determining the instantaneous range from the emitter source to the measurement platform.