Abstract: A method of manufacturing an annular base portion of an electrical slip ring assembly having a plurality of conductive rings formed in the outer circumferential surface thereof is described. The slip ring base is molded, and grooves are machined into the outer circumferential surface thereof. Conductive strips are cut into a series of lengths forming conductive rings to be placed about the outer circumference of the annular base member. The individual lengths of conductive material are anchored to the outer circumferential surface of the slip ring base and a rolling pressure is exerted on them about the circumference of the base to cause the rings to be press fit into the grooves previously formed on the base. When the complete circumference of the ring has been press fit into its respective groove, the other end of the conductive ring is then secured to the base.

Abstract: A pair of scanning, directional receiving antennas mounted in spaced relation on a monitoring aircraft are synchronously driven at a given scan rate .omega..sub.s and at the same phase angle with respect to the broadside of the antenna pair so that the receiving beams of the antennas are always parallel. A non-scanning source of RF radiation, located at an unknown range from the monitoring aircraft, emits radiation that is received by the scanning antennas at a slight time differential t.sub.21. The received source radiation is converted by separate receiving channels into early and late arriving signals, from which a time interval signal representing t.sub.21 is produced. Concurrently therewith, an angle of arrival .phi. of the source radiation is detected and a signal representative thereof is produced. Also, signals are generated that represent the scan rate .omega..sub.s of the receiving antennas and a distance d equal to the separation between the antennas.