Abstract: There is disclosed a digital frequency synthesizer which converts an ultrnic burst from an echo-ranging sonar system into a continuous signal having a frequency exactly equal to the frequency of the cycles making up the burst. This burst is detected and a number representing the period of this burst generated and transmitted to a first counter. A clock pulse train is generated and transmitted to a second counter. When the numbers in the first and second counters coincide, a single output pulse is generated and the second counter reset. When this cycle is repeated, the frequency of the resultant pulse train reflects any change in frequency of the cycles making up the bursts.

Abstract: This system is directed to an acoustic target simulator for use with active nd passive sonar systems. A receiver and a transmitter are mounted on the front and rear of the simulator. Separate high frequency channels are provided for the front transmitter and receiver and for the rear transmitter and receiver. The simulator utilizes a selector circuit that is operative upon receipt of a signal from one receiver-transmitter channel to disable the second receiver-transmitter channel. The simulator also includes a sonar becon which provides tracking capability for low-frequency sonars and an evasive action circuit which operates upon receipt of certain signals to disable the system.

Abstract: An acoustic imaging system for a wire guided torpedo having an array of tsducers arranged in the nose of a torpedo to receive acoustic signals. A spherical acoustic lens focuses the signals on the array of transducers. The outputs of the transducers are amplified, integrated, detected and passed to a set of gates which are sampled sequentially, and the outputs of the gates are passed by a wire to the launching vehicle.