Optical differential-modulation correlometer for the detection of linear-FM signals in noise

In order to extend the dynamic range of optical correlation analyzers in incoherent light, a differential-modulation technique has been developed which relies on high-frequency scans of the image of the signal record with respect to the reference record. The technique is applied to the analysis of linear-FM signals, and experimental results are presented. The results demonstrate the feasibility of using this differential-modulation correlometer to determine the presence, position, and amplitude of linear-FM signals. This technique makes it possible to perform the matched filtering of linear-FM signals in the region of null frequencies.