Magnitude-squared coherence filtering in a time difference of arrival (tdoa) or group delay interferometric geolocation system

Abstract

In a geolocation system for determining a geolocation of a target emitter, a method for determining the geolocation. The method comprising: (a) receiving a signal transmitted from the target emitter at each one of a plurality of sensors, a frequency spectrum associated with each signal; (b) determining a pairwise correlation between a first signal and a second signal from among the plurality of signals, the pairwise correlation determined at frequencies or within frequency bands within the frequency spectrum of at least one of the first and second signals; (c) identifying pairwise correlations below a predetermined threshold; (d) filtering the first and second signals by reducing a magnitude of energy at one or more frequencies or within one or more frequency bands to produce first and second filtered signals, the one or more frequencies or the one or more frequency bands selected responsive to pairwise correlations below the threshold; (e) determining a time difference estimate responsive to the first and second filtered signals; (f) repeating steps (b) through (e) for signals received at other of the plurality of sensors to determine additional pairwise time difference estimates; and (g) determining the geolocation of the target emitter from the piecewise time difference estimates.