Semi active laser target detection method with coherent reception

摘要

A target detection method is disclosed in which a target object Z is illuminated with coherent radiation S' from a laser designator DS and the radiation S reflected by the target is detected and coherently mixed by one or more detectors incorporated in a seeker. The differential signal obtained in a downstream detector D and lying in the frequency range between 0 and 10 GHz is narrow band filtered and processed further. The designator radiation may be modulated to allow information to be conveyed to the seeker. The disclosed heterodyne method is particularly suited for allowing a semi active laser (SAL) seeker to detect a designator using modulated continuous wave (CW) radiation in a sufficiently sensitive manner. CW designator radiation is distinctly harder to detect than the pulsed radiation of conventional laser warning systems.