CORRELATION METHOD FOR SURVEILLANCE DEVICE DETECTION

A new correlation process and implementing apparatus for use in detecting the presence and location of a concealed eavesdropping device is disclosed in the present application. The process correlates a demodulated intercepted signal with a reference signal that corresponds to the sounds present in an environment of interest. A high correlation between the demodulated intercepted signal and the reference signal indicates that the demodulated intercepted signal corresponds to the audio in the environment of interest. An improved Correlation process is implemented using Fast Fourier Transforms to calculate a figure of merit based upon correlation data determined from sampled versions of the reference and intercept signals. The improved process and apparatus further provides a range to the detected surveillance device and multiple range measurements may be used to triangulate on the surveillance device to determine its precise location.