METHODS OF RECOGNIZING TARGETS

In order to identify a target a data base is compiled containing records, for each of different known types of object, each record being derived from successive range sweeps of the object as seen from different angles and containing information defining the relative positions of different points of reflection on the object. In order to identify an unidentified object, information from at least one range sweep across it (and preferably a number of such range sweeps taken when viewing the object from different angles) is compared with similar information recorded in the data base to ascertain whether the unidentified object belongs to one of the known types.