Short baseline helicopter positioning radar for low visibility using combined phased array and phase difference array receivers

摘要

A helicopter position location system includes a receiver located substantially in a center of an array of receivers. A first array of receivers is located in a selected pattern separated from the center receiver by a first distance. Selected receivers in the first array are spaced apart from each other by at most one half wavelength of a base frequency of a locator signal transmitted from a helicopter. A second array of receivers is located in a selected pattern by a second distance larger than the first distance. A transmitter on the transmits a signal having a base frequency and a plurality of hop frequencies A processor in signal communication with the receivers is configured to determine phase difference with respect to frequency between any pair of receivers, to determine time delay of arrival based on the phase difference with respect to frequency, to beam steer response of the selected receivers, and to use the beam steered response and time delay of arrival between pairs of receivers to determine a position of the helicopter.