Patent ID: 6133869
Filing Date: 2000-10-17
Classification: G01S

Abstract:
A method of passively detecting the presence and location of an underground object comprising the steps of:(a) passively acquiring a plurality of low level random noise signals in the RF spectrum which are emitted and/or reflected by the underground object and by the intervening media;(b) conveying each of the plurality of noise signals acquired in step (a) as a separate channel to a radiometric receiver;(c) performing a mathematical integration for each separate channel received by the radiometric receiver;(d) generating from each of the integrated channels resulting from step (c) a plurality of simultaneous digitally synthesized electromagnetic fields of view;(e) directing the plurality of electromagnetic fields of view generated in step (d) at a plurality of different spatial angles;(f) performing an autocorrelation operation on each of the integrated channel responses;(g) computing an inverse Fourier transform on the result of step (f) and generating a spectrograph therefrom presenting power as a function of frequency; and(h) determining the location and depth of the underground object from the information contained in the spectrograph.