Abstract: A parallel to sequential message converter including a pair of signal terminals for receiving a first input signal having a duration of a first time period and a second input signal having a duration of a second time period which is less than the first time period, and wherein the second input signal is received concurrently with a portion of the first input signal so that a time overlap in signals exists. The first input signal is delayed at the onset of the second input signal for a period substantially equal to the time period of the second input signal. The second input signal is inserted into the signal stream at the start thereof and the delayed first input signal is thereafter reinserted so as to provide a sequential output of the first and the second input signals at an output terminal without a loss of any portion of the first input signal.

Abstract: A shallow water sonar apparatus and a method of processing outputs from a shallow water sonar array, where the array consists of at most two elements for receiving the acoustic energy from a plurality of directions. The apparatus also includes a beamformer for processing the acoustic energy received by the two elements to produce a tapered beam pattern which approximates a beamformer output from an array including substantially more than two elements. The tapered beam pattern is produced by asymmetrically amplitude shading outputs of the two elements, such that the output of one of the two elements is summed, without shading, with an output of the second element, shaded by a coefficient factor of 0.23.

Abstract: A control system connected to a passive underwater transducer array is located remotely from the array, e.g. above the surface of the water, to localize an underwater source of acoustic energy in a relatively simple manner by introducing listener-motion, such as head turning or body motion of a listener, into the sound localization process and does so without any underwater mechanical linkage of any kind. This is achieved by a pair of listener-motion coupled potentiometers, referred to as mixing-pots, located at the site of the listener, being connected to the outputs of an array of passive acoustic transducers, with the two outputs of the mixing-pots being coupled to a pair of headphones worn by the listener.

Abstract: A hydrophone having a hollow interior with signal electrodes on the interior surface and an electrically conducting coating over the entire outside surface. Signal leads are connected to the inside electrodes and the outside electrically conducting surface is connected to a point of ground potential to form an effective electromagnetic interference shield.

Abstract: A hydrophone array wherein each individual hydrophone of the array is comprised of, e.g. polyvinylidine fluoride (PVF.sub.2), tiles bonded to a substrate member opposite one another on opposite surfaces of the substrate. The substrate is a relatively stiff, metallic member having a Young's modulus of at least an order of magnitude greater than the PVF.sub.2 tiles which are oriented such that their stretch directions on either side of the substrate are parallel to one another. The directions of polarization of the tiles are either the same or opposite and electrical connections are made such that for a predetermined relative orientation of the directions of polarization, any output signal which may be caused by flexing or acceleration of the substrate is substantially reduced or eliminated.

Abstract: A system for weighing a vehicle in motion is disclosed. One or more piezoelectric weight sensors produce charge outputs in response to the weight of a vehicle passing over the sensors. A charge amplifier converts the sensor outputs to a voltage level. A peak voltage detector detects the peak voltage, which represents the sum of all sensor outputs. The peak voltage is then converted to a weight value using the thickness sensitivity of the piezoelectric material.