| 摘要 |
<p>Technique for passively detecting the presence and location of an underground object (24). A plurality of individual antennas (32) positioned in a linear array are directed to receive fields of view which are mutually parallel in azimuth. The array (32) is focused at a plurality of different angles in azimuth for acquiring low level random noise signals which are emitted by the underground object (24) and by the intervening media (30). A radiometric receiver receives the noise signals acquired by each of the antennas as a separate channel, digitizes them and forwards them to a signal processor performing operations including: mathematical integration for each separate channel; generation of a plurality of simultaneous digitally synthetized electromagnetic fields of view; directing the electromagnetic fields of view at a plurality of different spatial angles; autocorrelation of each of the integrated channel responses; inverse Fourier transform on the result of autocorrelation operation; generating spectrograph therefrom presenting power as a function of frequency.</p> |
