Abstract: An interrogation-answering system is employed in conjunction with a primary radar wherein a single joint transmitter is utilized both for generating the interrogation signals and the simple primary radar signals.

Abstract: When determining the detailed radar reflection cross-section of a radar target by ISAR techniques it is a known problem that one of the target motion components is to be compensated. This was done in the past by complicated numerical calculations of the path of the target. According to the described method, the motion compensation is determined by means of an auxiliary signal which is transmitted form the target. The described method enables the achievement of a radar reflection cross-section by real time data processing of the signals received. Also an apparatus for performing the method is described.

Abstract: A signal is transmitted from a first location to a remote second location where a target carrying a transponder is positioned. The transponder re-radiates the signal to the first location where it is received. A phase comparator generates from the transmitted and received signals a measurement of their phase difference which is functionally related to the distance between the first and second locations. In one embodiment, the transponder is a passive parametric oscillator, being powered by energy received from the transmitted signal, which generates and transmits a subharmonic of the transmitted signal.

Abstract: A microwave deviation measurement receiver particularly applicable to airborne secondary radars making deviation measurements with two logarithmic amplifiers which increase the reliability of deviation measurements for targets close to the direction of aim of the radar. A programmable phase shifter preferably is controlled to compensate for aircraft movements by shifting the phase of the sum or control signal.