Abstract: The present invention relates to a method of and apparatus for identifying a selected radar target in which an initial interrogation radar pulse is transmitted from a base station and received at the selected target x and any other such radar targets y z at which it is applied to a respective responder causing the responder to generate a monitor response signal x1, x2, y1, y2, z1, z2 with a pulse separation tr not less than the duration of an identification signal. Each said target x, y, z receives one or more monitor response signals x1, . . . z2 from the other radar target responders. Any monitor response signals y1, y2, z1, z2 received partly overlapping the monitor response signal x1, x2 of any of said radar targets are detected and a garble flag means set thereat.

Abstract: A method for identifying radar targets, especially ships at sea involves transmitting a first interrogation pulse, thereby causing a responder to generate a first identification signal containing a first set of data concerning the identity of the target, transmitting a second interrogation pulse causing the responder to generate a second identification signal containing a second set of data concerning the identity of the target and thereafter combining the two sets of data. The method reduces bandwidth requirements and garbling. An interrogator and responder for use in the method are also provided.