Abstract: A plurality of transducers is arranged successively on a common impedance matching layer of a resilient material. Each transducer comprises an elongated piezoelectric element having a width expansion vibrational mode, a pair of first and second electrodes attached to opposite surfaces of the element across its thickness and an elongated block of an impedance matching material disposed between the second electrode and the common impedance matching layer. The common impedance matching layer is bent to take the shape of an arch to conform to the surface of a frame structure which is convexed in the direction of propagation of ultrasonic energy. The piezoelectric elements are secured to the frame so that they bridge the parallel side members of the frame. The piezoelectric members are divided into a plurality of subgroups, each composed of successively arranged elements.

Abstract: Variable focus in a sonar system of the time delay beamformer type using a onvexly curved electroacoustic array is achieved by changing the operating frequency.

Abstract: The radiation pattern of shaded single element piezoelectric transducers and transducer arrays has reduced side lobe levels. Shading to reduce the intensity of emitted ultrasound at the edges of the transducer relative to the center is realized by varying the electric/acoustic conversion efficiency or polarization of the piezoelectric material, by having different mechanical element lengths, by selectively poling the piezoelectric material to produce poled and unpoled regions, and by control of electrode geometry. The shading of a phased array ultrasonic transducer is described in both lateral dimensions.

Abstract: Apparatus utilizing a combination energy transmitting and energy receiving transducer or a transducer set consisting of separate energy transmitting and energy receiving transducers, are employed to detect and subsequently indicate the presence of an object(s) within one or more of a plurality of spaced-apart spacial zones.

Abstract: A detection system for imaging by sonar or radar signals. The system associates diversified transmissions with an interferometric base. This base provides an angular channel formation means and each signal formed in this way is processed by matched filtering in a circuit containing copy signals characterizing the space coloring obtained by the diversified transmission means. The invention is particularly applicable to side or front looking detection sonars.

Abstract: An ultrasonic transmitter-receiver is characterized in that a diaphragm is disposed at the center of a laminated piezo-electric element and the periphery of the diaphragm is flexibly fixed in a housing through a buffer member of elastic rubber or the like in order to suppress mechanical oscillation.

Abstract: A bidimensional imaging system by echoes including a transmitting array and a receiving array. The transmitting array includes a row of transmitters (E.sub.1, E.sub.2, . . . , E.sub.i, E.sub.N) parallel to a direction Oz and the receiving array includes a row of receivers in a direction Ox. All the transmitters simultaneously transmit signals with different codes. The signals received are demodulated and the real and imaginary components of these signals are applied to two multiplexing circuits (61.1, 61.2). After modulation the multiplexed signals are applied to a Fourier transformation circuit (63), which sequentially supplies reception channels V.sub.k (.theta..sub.k) for the direction referenced by angle .theta..sub.k and which are stored in memories (66.1, 66.2). Other memories (70.1, 70.2) contain signals S.sub.i (.phi..sub.i) transmitted in an angular direction referenced by .phi..sub.i. The two pairs of memories (66.1, 66.2 and 70.1, 70.

Abstract: An ultrasonic transmitting and receiving device comprises a bimorph vibrator including two piezoelectric elements each connected electrically to the corresponding one of a plurality of terminals for receiving and delivering electric signals and a metallic member made of a thin metal plate and including a flat plate portion and a cylindrical portion extending from the circumferential periphery of the flat plate portion. The flat plate portion is placed between the piezoelectric elements and the cylindrical portion increases in outer diameter as it becomes distant from the flat plate portion.

Abstract: A device for forming an image of an object by means of ultrasound beams, comprising an array (1) of electroacoustic transducers, means for connecting a selected group of transducers to a delay unit (17) which is arranged to delay the electric signal generated by each transducer of the group by a predetermined period of time and to sum the delayed signals in order to form a resultant signal which is an electrical representation of the acoustic signals originating from a selected distance or from a selected direction. The delay unit (17) is formed by a tapped delay line (19), whose taps (21) serve as inputs for the signals originating from the various transducers and whose output (23) is connected to a signal processing device (25) for the further processing of the resultant signal. Signals are applied to the taps through current sources. The applied signals may be selectively attenuated to effect apodization of the ultrasound beam.

Abstract: A narrow band compensating beamformer for a receiving array that conforms some surface other than a plane and thus is, in general, three dimensional. The array comprises a number of sensing elements arranged in a non-planar pattern. Each sensing element has its output signal delayed or phase shifted as a function of the receiving angle by the beamformer in such a way as to produce an equivalent "projected planar array" in a particular direction. This arrangement has the same beam pattern in the selected direction as an equivalent planar array with its lower side lobe characteristics permitting the taking of advantage of well known, low side lobe shading techniques.

Abstract: A method and apparatus for determining the phase angle of the sensitivity of a hydrophone H to be calibrated. The method comprises positioning in a straight line a transducer P, the hydrophone H, and a reciprocal transducer T that can be used both as a hydrophone and a projector; determining the phase angles of a set of voltages and currents; and finding the phase angle of the sensitivity from the former phase angles. The apparatus includes a framework for positioning P, H and T in a straight line, an electronic system for monitoring the voltages and currents, and a programmed computer for performing a single-point DFT.

Abstract: In an ultrasonic wave distance detection system, an ultrasonic wave pulse radiated into the selected area is reflected on an object. Said reflected ultrasonic wave pulse is partly received by an ultrasonic wave transducer. The received signal is supplied to a variable gain amplifier, noise components are removed from the amplified signal through a band pass filter, the noise removed signal is detected by an envelope detector, the detected signal is compared with a predetermined level by a comparator, and the output of the comparator is applied to a flip-flop circuit.As the gain of the variable gain amplifier is set to be a lower level only at the beginning of the ultrasonic wave pulse to minimize the amplification of unnecessary signals without reducing the detection efficiency, a signal can be surely obtained which has a pulse width corresponding to the distance between the system and the object and thus the distance can be detected or measured.

Abstract: A continuous transmission FM sonar avoids target ambiguities while utiliz the entire transmitted bandwidth for echo analysis. The sonar is characterized by digital generation of direct and quadrature versions of the transmitted frequency sweep, and balanced modulators responsive thereto to effect complex demodulation of the returned signals prior to analysis, as by a fast fourier transform frequency analyzer for target detection.

Abstract: This disclosure is concerned with problems of energy conservation and more effective utilization at desired critical times only in, for example, sonar-triggered underwater elapsed time strobe photography of objects or scenes or in applications having similar problems; accomplishing such and other ends by restricting optical and sonar monitoring to relatively low periodicity intervals until the desired object has come within range, whereupon the apparatus automatically changes mode to take rapid successive strobe photographs or other records supplemented by contemporaneous sonar recording.

Abstract: An acoustic ocean measuring system is disclosed which uses measurements of sound intensity to locate and measure ocean anomalies. Several free-floating sound pulse emitting floats are placed in the ocean area to be measured; the position of the floats can be determined by well-known ranging techniques. Several hydrophones are positioned either in the immediate area or at distant locations to receive the sound pulses. A fixed number of received sound signals are electronically processed to obtain peak intensity signals. A fixed set of peak signals received from the floats over a fixed period of time are used to generate a trend line which can be used to predict the peak intensity received from the position data. The actual received intensity measurements are compared to the predicted measurements; substantial deviations from the predicted values are used to locate and measure parameters of ocean anomalies.

Abstract: In an on-bottom seismometer, the electronic system for operating the release mechanism includes a plurality of independent power sources. A plurality of release condition sensors each produce a release output upon the occurrence of a condition in which the unit is to be recovered at the water's surface. Logic circuitry responds to the release condition sensors for producing a relase signal which is applied to driving circuits for primary and secondary release devices. Switching means automatically connect the logic circuitry and the driving circuitry to an operable one of the power sources.

Abstract: In an industial installation which is inaccessible during operation, acoustic-emission testing of each measurement line is performed by means of at least one transducer and a preamplifier which is connected to an acoustic signal processing unit by means of a signal transmission line and a supply line. A potentiometer circuit placed on the supply line produces a variation in the supply voltage and remotely operates a relay for switching the measurement line to testing means comprising a local pulse generator connected between the transducer and the preamplifier.

Abstract: A sonar transceiver system and method includes an oscillator and programmable divider which are arranged to cause a transmitting transducer to transmit a plurality of four consecutive closely spaced tones in the manner of a pseudo-chirp. The receiver includes hard limiting means for converting received echo signals to binary signals and tone correlation and detection means including a shift register which compares samples of the binary received signal with a sample of a sine wave as hard limited which is carried on a storage register. A series of exclusive-OR comparator circuits effect the comparison and produce output signals of a desired magnitude when correlations are found. Switching means responsive to detection of the first of the transmitted tones causes the programming means to vary the divisors of the programmable divider to produce clock pulses of varying frequency to the shift register for the time and in the order of the transmitted tones.

Abstract: An ultrasonic wave transmitter and receiver adapted to be mounted on the rear portion of a vehicle to detect the distance between the rear end of the vehicle and any obstruction located at the rear side of the vehicle. The ultrasonic wave transmitter and receiver includes an ultrasonic transducer attached to a lower part of the vehicle at a portion spaced from the rear end of the vehicle in the forward direction of the vehicle by a predetermined distance, a horn opening rearwardly from the vehicle and a wave guide tube through which the horn and the ultrasonic transducer are coupled to each other. The distance between the ultrasonic transducer and the rear end of the vehicle is selected to correspond to a time length which is long enough to sufficiently attenuate the residual oscillation of the ultrasonic transducer.

Abstract: Alarm and intrusion type identification signals are derived from the output of a security system transducer by a signal processor. The signal processor conditions the transducer output signals to provide rectified and unrectified high pass and low pass frequency signals; develops signals representing either human or vehicle intrusions from the high pass frequency signals; develops signals representing intrusion events from the low pass frequency signals; and, logically classifies each intrusion event as either human or vehicle. Intrusion type identification signals are developed by counting zero crossings of the unrectified high pass frequency signal, measuring current energy of the rectified high pass frequency signal and logically comparing the two values.