Spectrum analysis systems using optical correlation techniques particularly useful in pulse modulated doppler radar systems

Claim 1

A spectrum analyzer system using optical correlation techniques in real time with non-coherent light, comprising: a. transducing means for converting a signal to be analyzed into an optical modulated beam, the frequencies of said signal being included in the measuring spectrum of the spectrum analyzer; b. a plane support associated to moving means enabling a displacement at a constant speed, having a plurality m of parallel tracks representing in the form of variable transparency m different frequencies at the rate of one frequency per track, the value of said frequencies being determined by displacing said measuring spectrum (F1-F2) by a predetermined frequency value ( Delta F), dividing said frequency displaced measuring spectrum into m successive elementary frequency bands having a common frequency bandwidth value, selecting central frequencies of said elementary frequency bands to constitute said respective track frequencies, so as to provide by correlation between said track frequencies and corresponding respective central frequencies of said measuring spectrum a beat-frequency equal to said frequency displacement value ( Delta F); c. a plurality m of photoreceivers in the correlation plane optically associated respectively to said m tracks, each feeding a selective filter, said filters being identical, each having a central frequency equal to said beat frequency ( Delta F) and a maximal frequency bandwidth equal to said common frequency bandwidth value of said elementary frequency bands; and, d. a utilization unit fed by detection circuits following said filters, and enabling analog processing.