Abstract: An ultrasonic signal transducer is characterized in that the piezoelectrically active element has a first unitary electrode over the entire surface of one face and a matrix of a plurality of individual electrodes on the opposite face. In the receive mode, such an arrangement effectively constitutes a plurality of individual transducers arranged in the matrix array while maintaining the efficacy of a unitary structure. The signals from the individual electrodes are individually amplified, full-wave rectified, and combined additively to produce a composite signal which eliminates the phase cancellation of the ultrasonic pulses distributed over the face of the transducer assembly.

Abstract: The invention relates to a novel helium-speech unscrambler which can be located at a diver's location, and enables the helium-speech voiced by the diver to be subjected to waveform time expansion to reduce the bandwidth of the helium speech (e.g. to 2 to 3 KHZ) prior to transmitting the speech signals to a distant location on a carrier wave selected for optimum transmission through the water.

Abstract: A probe primarily applicable to medical echography for achieving a variable compromise between depth of field and lateral resolution incorporates a main piezoelectric transducer, a plano-convex lens having an elastic diaphragm, an auxiliary transducer for measuring the deflection of the lens and means for controlling the deflection in dependence on a reference value by modifying the pressure exerted on the diaphragm by the fluid contained within the lens.

Abstract: An automatic trolling depth controller is disclosed for a fishing boat employing a downrigger system. A sonar depth indicating unit with a sonar transducer continuously measures changing depth as the boat trolls. A depth control unit is connected thereto which automatically raises and lowers the trolling line via a reversible motor in response to depth indicating signals of the depth indicator unit so as to automatically maintain the end of the trolling line at a substantially constant given spacing from the bottom despite variations in lake depth as the fishing boat trolls.

Abstract: Seismic detection of a target is obtained with a geophone detecting earth vibrations caused by the actions of the target. The vibrations are wide band amplified and band-passed filtered with the pass bands being fed to the threshold detectors. The outputs of the threshold detectors are fed to a diode AND logic circuit, the output thereof indicating the presence of a target.

Abstract: An oscillator generates a fixed frequency ultrasonic output signal. After wer amplification this signal drives a transmitting transducer which projects an ultrasonic beam into water. Reflected signals are received by a receiving transducer and AGC preamplified. A chopper multiplies the received signal with the transmitted signal and generates an output signal if a target exists. To determine whether the target is a swimmer, this output signal is band pass filtered and amplified and then fed both to an automatic alarm and to a set of headphones. A human operator listening to the headphone output classifies the target and determines exact bearing.

Abstract: A bi-directional underwater communication system provides a submerged operator with the capability to communicate with a surface site. A face-mask-mounted microphone and an earphone are connected to a submerged, watertight radio. The radio antenna cable is carried by a buoy to the surface of the body of water in which the operator is submerged.

Abstract: A multiplexer for an ultrasonic ranging device for a vehicle having a resettable digital counter is disclosed herein. The digital counter receives a plurality of pulses from an oscillator and provides a counter output signal indicative of the stored count of the number of pulses. A plurality of logic gates are connected to the digital counter for control thereby. A plurality of ultrasonic transducers are connected to the logic gates, the logic gates sequentially energizing the transducers in response to the stored count in the digital counter.

Abstract: A device for forming beams for mulitple elements of a hydrophone array. An nalog multiplexer receiver sequentially obtains one signal from each hydrophone and supplies input voltages to an analog to digital converter. Digital words from the converter are applied to one input of a digital adder and the other adder input is from the output of a random access memory (RAM). The output of the adder is stored in the RAM at an address corresponding to the signal time delay required from a particular hydrophone in order to direct the beam of the hydrophone array in a desired direction.

Abstract: Wind is the large-scale movement of air from one place to another. It is usual for the air to become horizontally stratified, the layers nearer the ground moving more slowly than or in a different direction to those higher up. This change of wind speed with height is known as wind gradient (or wind shear), and it may cause serious problems for aircraft during their approach and landing.Unfortunately, at present there is no satisfactory way of ascertaining the wind gradient situation.The invention provides acceptable apparatus for, and a method of, actually detecting--and preferably measuring--wind gradient at a location, and involves a comparison of the wind speed in the same direction at two or more heights at the location, this comparision being upon the basis of a comparison of the speed of sound in that direction and at those heights, a difference in the apparent speeds indicating the presence of wind gradient.

Abstract: A marine depth sounder uses digital techniques to enhance the image of a received acoustic pulse for providing expansion of a portion of the range information with high resolution.

Abstract: The underwater signalling and identification device comprises an emitter (5) having four submerged transducers (10 to 13) arranged to form a square and fitted in a water-tight case (25) placed above an opening (7) formed in the hull of a ship, and also comprises a transducer-control circuit designed to emit an identification signal specific to the vessel and made up of a series of figures or letters in Morse code, the signal being emitted at at least one frequency selected as a function of the sound spectrum of the vessel and falling within the range of 4 to 6 kHz, the strength of emission of the signal being in accordance with the relationshipLI.sub.sl .gtoreq.LI.sub.bl +.DELTA.(dB),wherein LI.sub.sl is the level of acoustic intensity converted to the unit of distance of the identification signal of mean frequency f.sub.s.

Abstract: A plurality of acoustical transducers such as microphones are placed in appropriate array so that they are capable of detecting sonic energy emanating from an acoustical source such as an aircraft or a ground vehicle. The outputs of the transducers are sequentially sampled and multiplexed together, the time multiplexed signals then being converted from analog to digital form in an analog/digital converter. The output of the analog/digital converter is fed to a fast Fourier transformer (FFT), which transforms these signals to Fourier transform coefficients represented as real and imaginary (cosine and sine) components. The output of the fast Fourier transformer is fed to a digital processor. In this processor, the power and phase of each frequency bin for each microphone output is determined and the phase differences between signals received by pairs of microphones for each frequency bin of interest are determined.

Abstract: Apparatus for suppression of water flow noises in connection with a keel nted sonar dome. A solution of water soluble polymer is ejected through a series of holes along the leading edge of the sonar dome under forward movement of the ship. The concentration and flow rate is chosen to "bathe" the dome in a very dilute dispersion (of the order of 10 parts per million by weight) of the polymer.

Abstract: A method, a device and a transducer for dimensional measurement of objects by means of ultrasonics, where the objects are carried past at least an ultrasonic measuring device consisting of a combined transmitter/receiver or separate transmitter/receiver. The reflected ultrasonic signals are used to determine characteristic three-dimensional dimensions of the objects. Said device or devices are arranged either such that the ultrasonic beam or beams therefrom are provided with a reciprocating movement which substantially crosses the direction of movement of the objects or by letting the ultrasonic beam or beams therefrom be stationary. The delay of the reflected signals is used to form a three dimensional image of the object by means of a computer, said image being compared with known images for identification. The ultra sonic measuring device has a narrow, substantially rotation-symmetric radiation diagram.

Abstract: A curved faced, disc shaped transducer and an oppositely facing, circular angularly disposed mirror form the transmission and reception path of a mechanical sector scan imaging system. The transducer and mirror are mounted on a common axis, and a shaft upon which the mirror is affixed oscillates about that axis. Through a belt drive mechanism, a motor provides the oscillating motion, in turn scanning the ultrasound beams through the subject by virtue of the mirror motion. An optical encoder records positional information from the motor, for coordination of the mirror oscillation with transducer signals, and thereby for the assembly of a composite image.

Abstract: A sonar bearing determining system comprises a generator for radiating a sonar signal and a receiver for receiving echo signals. The receiver comprises an array of spaced receiving transducers and a modulating and sampling arrangement which consists of a multiplexer driven by a clock signal for producing a combined signal. The combined signal is of the form of a repetitive sequential sample of each of the received signals modulated by a signal equal to the multiplexing signal but phase displaced relative thereto. A bearing determining device is arranged to determine the bearing of an object providing an echo in dependence upon the frequency component of the combined signal or in dependence upon the time displacement of the combined signal relative to a predetermined time value. The modulating and sampling means is arranged to route selectively samples of each of the received signals and thereby to effect both modulating and sampling functions.

Abstract: A digital sonar system including a redundant receiver channel is arranged to operate substantially simultaneously in both F.M. and C.W. modes. Upon failure of one receiver channel the system reverts to a single mode or alternate modes on alternate cycles.

Abstract: The disclosure relates to a system of automatically controlling the distance between two members placed in a relatively variable relation with each other with respect to distance on a straight line. One of the two members is provided with a transmitter capable of generating an ultrasonic pulse excellent both in directivity and in damping characteristics, and the other is provided with a receiver with the same in characteristics as the transmitter and which is disposed in an opposed relation with respect to the transmitter. The distance between the two members is automatically controlled by causing an ultrasonic pulse to be transmitted and received respectively by the transmitter and the receiver.

Abstract: The disclosure relates to a system for aerially transmitting an ultrasonic view of a vibration mode, small in angle of direction, in a clear state and to a transmitter and a receiver used in the system. According to the system, an ultrasonic pulse can be used for distance measurement, control and other signal means even at relatively short distance.