Abstract: An underwater combination of a passive and an active acoustic mechanism is sed to detect and locate a surfaced or submerged object or target. The passive mechanism utilizes a pair of separated hydrophones to detect an object. The hydrophones are then followed by bandpass filters according to the frequency of interest and the outputs thereof correlated to locate the object. A positive correlation output indication initiates the active acoustic mechanism which then verifies the detection of an object by transmitting a pulse sonar. The output of a transducer responsive to the reflected pulse sonar is then analyzed to indicate whether the detected object is surfaced or submerged and whether the detected object is approaching, departing or stationary.

Abstract: An acoustical line array transducer reflector system for producing conical hell radiation patterns. One side of the ground plane reflector of the system is covered with a chloroprene rubber-cork composition. Three transformers in ferrite cup cores are wired to the line array transducer elements.