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: A method and apparatus for determining the depth of a marine target relat to the surface of the water which encompasses an analog processing circuit for detecting and analyzing signals reflected respectively from a target and the water surface, a timing and gating circuit respectively responsive to a target echo signal for initiating a timing sequence and to a surface echo signal for terminating the timing sequence, and a depth readout circuit for indicating the depth of the target below the surface at the instant the surface echo signal terminates the timing sequence.

Abstract: A bulkhead for a marine seismic streamer section comprises a generally cylindrical body of rigid tough plastics material such as polycarbonate polymer, having an axial hole therethrough, through which passes the electric conductor bundle of the streamer section, and peripheral radial slots with hemicylindric bottoms receiving the tension lines of the streamer section. The bulkhead has an annular circumferential groove which is radially as deep as the axes of the bottoms of the slots and in which is disposed a belt of phosphor bronze, or stainless steel, or other strong corrosion resistant metal. The belt holds the tension lines in the slots and holds together the bulkhead, which is made of two sectors. One sector is greater than 180 degrees in extent and the other is less than 180 degrees in extent, e.g. the one sector may extend 240 degrees and the other 120 degrees.

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.