Abstract: A piezoelectric transducer assembly for producing sonar signals for transmission underwater and for detecting reflected sonar signals. The assembly includes a two-dimensional generally planar array of piezoelectric elements disposed in an elastomer casing. The elements are coupled by way of conductors to electronic circuitry which produces electrical signals for stressing the piezoelectric elements and which processes electrical signals produced by the piezoelectric element in response to reflected sonar signals. The piezoelectric elements are closely packed and are selected to have low cross-coupling characteristics. At least some of the elements are oriented so that their axes of polarization are generally perpendicular to the plane of the array.

Abstract: A flexible line array transducer assembly for detecting underwater acoustical signals. The assembly includes an array of spaced-apart piezoelectric elements arranged generally in a line and selected to have low cross-coupling characteristics, low sensitivity to incoherent mechanical perturbations in the directions longitudinal and lateral to the axis of the array, and high sensitivity to coherent mechanical perturbations such as acoustical signals. The elements are polarized in a direction generally transverse to the array and each include opposing surface areas which are generally parallel with the linear axis of the array. Electrodes are disposed on the opposing surface areas of the elements and are coupled to conductors which carry signals produced by the piezoelectric elements when the elements are stressed by acoustical signals. A porous, open-cell material is disposed about the piezoelectric elements as an encasement to maintain the elements in place and mechanically isolate the elements.

Abstract: A deep water tow system adapted for being towed by a tow cable behind a ship includes a buoyant tow vehicle for housing apparatus to be used underwater, a coupler for connecting the tow vehicle to the tow cable, and a weight in the form of a multi-link chain attached to the tow cable at a location some predetermined distance from the tow vehicle. The chain is of sufficient weight to pull the tow vehicle downwardly in water until the chain contacts the water floor. When pulled by a surface vessel, the chain is pulled over the water floor and the tow vehicle is maintained some fairly constant predetermined distance above the water floor.

Abstract: Method and apparatus for detecting the presence of liquid in a container includes an elongate rod (or other vibratory element) which extends into the container to contact liquid when a certain amount of liquid is present, a piezo-electric element coupled to the rod on the exterior of the container to cause the rod to vibrate in response to electrical signals and to produce electrical signals indicative of the amplitude of vibration of the rod, and circuitry for producing a utilization signal when the electrical signals produced by the piezo-electric element indicate that the amplitude and duration of vibrations of the rod are below some threshold level. Such vibrations fall below the threshold level when the rod contacts liquid in the tank and so production of the utilization signal is an indication that liquid in the container has reached a certain level.