Patent ID: H0002224

Claim:
A multiple configuration, self-calibrating baseline interferometer radio frequency emitter locating apparatus using two aircraft comprising the combination of: a first search aircraft containing a first radio frequency measurement receiver, a first radio frequency antenna and a first variable delay component; means for determining a path distance between said first radio frequency measurement receiver and said first radio frequency antenna; a second aircraft containing a second radio frequency measurement receiver, a second radio frequency antenna and a second variable delay component; means for determining a path distance between said second radio frequency measurement receiver and said second radio frequency antenna; time difference of arrival, phase difference of arrival and phase difference of arrival rate processing apparatus disposed in each of said first and second radio frequency measurement receivers of said first and second aircraft; and selectively operable signal propagation time delay calibration apparatus connectable with signal propagating paths interconnecting said first and second aircraft; wherein a signal received by said first radio frequency antenna and a signal received by said second radio frequency antenna are used by said processing apparatus to calculate time difference of arrival, phase difference of arrival, phase difference of arrival rate; and means for geo-locating said emitter by using down range and cross range time and angle error curves to straight-line graph time difference of arrival and phase difference of arrival whereby the time difference of arrival gives an azimuth angle to the emitter and the intersection with the aircraft altitude gives emitter elevation, the time difference of arrival rate and phase difference of arrival determines range and emitter location.