Abstract: Disclosed as a beamforming system, particularly useful for seismic exploration or undersea surveillance, in which data processing of the system is done optically. Sensor outputs are subjected to plural sets of time delays, and the system beams formed optically. Four embodiments are presented of the optical processing hardware.

Abstract: In an ultrasonic beam former for phasing and adding received signals supplied from respective elements of an ultrasonic transducer array and for producing the received output in conformity to a desired wave front, a plurality of sampling delay means for sampling and delaying the received signal supplied from each element are disposed for each channel. The plurality of delay means effect the sampling operation successively and alternately. Outputs of delay means are selected by switches activated in response to the alternate sampling operation. As a result, the sampling rate per signal channel is increased.

Abstract: In the ultrasonic wave phase matching diagnostic apparatus described in the specification, an array of ultrasonic transducers is arranged to transmit ultrasonic waves to an object to be investigated and to receive ultrasonic waves returned from the object. Focusing of the waves to a point in the object is accomplished by selective delaying of the transmitted signals from each of the ultrasonic transducers, and similar delays are imposed on received signals to define a focal point for signals received from the object. Scanning of the object is provided by stepwise changes in the ultrasonic transducers used for transmitting and receiving ultrasonic signals, and half-pitch scanning may be effected by using different numbers of ultrasonic transducers for transmission and reception of the ultrasonic waves.

Abstract: A sound processing arrangement couples sound from a prescribed environment through a fixed microphone array to a signal processing arrangement having a specifiable preferred sound source location. The microphone pickup signals are combined with a set of weighting signals to adjust the directional response pattern in successive analysis time intervals. The weighting signals are modified in each analysis time interval so that the total acoustic signal power of the signal processing arrangement output signal is decreased toward a minimum while substantially unity power transfer of sound signals from said preferred location is maintained at all frequencies over a prescribed frequency range. In this way, the preferred source location is in the main beam while unwanted sound source locations are at the null points of the adjusted directional response pattern.

Abstract: A device for electronic focusing of ultrasonic waves in which the focusing means comprise a hierarchized assembly of elementary circuits each provided with a delay line connected in parallel with a direct line to a centralizing unit and in which the time-delay of the delay line in a circuit is a function of the relative time-delay which must exist between the two cells or the two circuits connected to said circuit. It is shown that, in the invention, a technological advance is achieved by thus minimizing the maximum time-delays to be established in the case of each delay line.

Abstract: An electro-acoustic transducer according to the invention is of the Tonpilz type comprising a stack of piezo-electric plates placed between a horn and a countermass, and electrodes inserted between the plates. Some of the electrodes are connected to a common excitation or output conductor through phase-shifting circuits which allow the electric voltage of a proportion of these electrodes to be dephased. A logic unit allows the phase-shifting of the electrodes to be distributed within the stack according to several different groupings in dependence upon frequency. One application of the invention is to the construction of long-range power sonars.

Abstract: This invention relates to apparatus and a method of controlling the amount of delay or phase-shift which is applied to a signal received at or transmitted from each transducer in a multi-transducer antenna to produce a beam directed at a specific target point. For each transducer a first look-up table is used for storing first digital words representative of the included angle between the lines joining the target to a reference point, and the same reference point to a transducer. A second look-up table is associated with the first look-up table for each transducer, and stores second digital words representing delay or phase-shift control signals corresponding to ranges of the target relative to the reference point for each of said first digital words. Each first look-up table is addressed with an address signal representing the direction of the line from the reference point to the target, to obtain a corresponding first digital word.

Abstract: In an ultrasonic imaging apparatus, when a sampling time space determined corresponding to the respective phases of receiving signals from transducer elements adjacent to each other is shorter than the settling time of sample and hold circuits, these receiving signals are sampled at the same time. Noise is prevented from being mixed with the sample and hold values of these signals.

Abstract: A multibeam acoustic apparatus utilizing a linear array of hydrophone elements in a sonar system includes a cascaded ladder capacitance-inductance network for coupling electrical signals to and from the individual hydrophone elements. The hydrophone elements are connected in series and the natural capacitance of these elements provides the capacitive characteristics of the network. Shunt inductors supply the inductance characteristics and provide a phase characteristic inversely related to frequency. Variable cumulative phase delays are provided for signals applied to successive hydrophone elements whereby a sonar beam is formed in a direction determined by the frequency of the exciting signal.

Abstract: A passive sonar system which forms multiple receiver beams for detection of possible targets. The transducer array for the system includes a plurality of pairs of transducers, the transducers of each pair lying along a generally radial line emanating from a central point. The output signal from the outer transducer of each pair is delayed by 90.degree. or .lambda./4C relative to the inner transducer, and the delayed signal is combined with the output signal from the other transducer of the pair in a summing amplifier so that only one signal per transducer pair need be sampled by a multiplexer for transmission via a coaxial cable to beamformer apparatus. The concept is applicable to groups of transducers with more than just a pair, i.e., with three or more transducers. Appropriate additional delays are provided with all of the output signals and delayed output signals of a group being received by a single summing amplifier.

Abstract: An apparatus for determining the transit time of ultrasonic pulses in a fluid has two spaced apart electro-acoustic converters (11, 20). A transmitter signal proportional to the sound pressure is applied via a controllable delay circuit (23) to a multiplication circuit (25) to which the received signal is also passed. The product signal is in turn passed to a transit time detector circuit (10) (FIG. 1).

Abstract: A digital device for forming spatial channels for sonar equipment having a sonar transducer array including N sensors. Signals from the N sensors are sampled and multiplexed in series. A memory having a plurality of memory blocks stores the samples of the sensor signals. The memory blocks may conveniently be divided into two groups. The group acquires samples during a time interval T.sub.c from the N multiplexed signals. Each memory block thus stores P groups of N samples. The samples stored in one memory block are then transferred to the next block. Finally, the samples stored in each memory block of the first group are transferred into the corresponding memory block of the second group in which the delayed samples are read and summed to deliver simultaneously Q time samples of the same spatial channel.

Abstract: An array of acoustic transmit/receive transducers is placed near the body to be imaged. Acoustic energy is projected upon the body sequentially from different ones of the transducers, each projection covering the entire scene or field of view which it is desired to image. The electrical signals produced from reflected acoustic energy picked up by different transducers are phase shifted, or time delayed as appropriate, so that those from any particular point within the body will additively combine in amplitude, while signals from other points will not. In so doing, there is preserved not only the information about the amplitude of the combined signal from the transducers, but also any information about phase shifts (or time delays as the case may be) which does not result in complete alignment of the signals from the different transducers. The resulting complex signals are further processed, to vectorially add them.

Abstract: A sonar beam steering arrangement in which a circular array of electroacoustic transducers are sampled in sequence, the samples being digitized and stored serially in a shift register. The register is several cycles long so that samples from all of the `illuminated` transducers can be stored simultaneously. The various stages have resistance tappings of different values such that a linear broadside array is simulated for a particular transducer at a particular stage in the shift register cycle. As the samples progress through the register each transducer in turn acquires this simulated broadside array and thus provides a narrow beam 360.degree. scan. Interpolation between adjacent transducer `dead-ahead` direction is obtained by (e.g.) triplicating the shift register and adjusting the weightings slightly from each register to the next.

Abstract: In a panoramic sonar for underwater detection, a channel formation device supplies channels sequentially over 360.degree. from a circular base of N receiving transducers, one channel being formed from M transducers. The signals received by the N transducers are multiplexed and applied to two subassemblies. One subassembly is composed of shift registers corresponding to N and N-1 cells (C.sub.N, C.sub.N-1) and the other subassembly is composed of shift registers corresponding to N and N+1 cells (C.sub.N, C.sub.N+1). Taps on the subassemblies make it possible to obtain the delayed signals corresponding to the M receiving transducers. The signals are summated and applied sequentially to the channels.

Abstract: A range measurement system for a submarine also having a passive monitoring system with a beam forming circuit, one beam of which may be selected by a signal V.sub.N from a tracking computer. Two assemblies of three hydrophones are located respectively on the port side and on the starboard side of the submarine. The signals supplied by these receivers are correlated with a beam signal S.sub.V of the passive monitoring system selected supplying the delays of these signals. A computer receiving these delay values supplies to the tracking computer the values of the bearing angle .alpha. and the distance D of the noise source.

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: 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 circuit arrangement for forming a succession of group signals in the ranging art from received signals originating from an array of adjacent signal receiving transducers, each successive group signal being associated with a respective group characteristic and being based on the signals received by a respective group of adjacent transducers forming part of the array. The succession of group signals is processed to form a representation of the mean, or average, value of a predetermined number of successive group signals, and a representation of the ratio of the value of one of the group signals of that predetermined number of signals to the mean value is produced.

Abstract: A sonar array wherein the capacitance associated with the hydrophones of the array are utilized as shunt elements in an artificial transmission line in order to form an acoustic beam. Series inductance elements to the transmission line are variable with d.c. current flowing through coils wound about a magnetic core about which coils forming the series inductance of the line are also wound, thus permitting the sonar beam to be steered to any desired position.

Abstract: This invention is a hydrophone (element) sited beamformer which is coupled to an array cable of a horizontal line array. A hydrophone-sited beamformer is coupled to each hydrophone in the array. The element-sited beamformer directly forms beams from the data detected by the hydrophones by delaying and selecting some of the hydrophone detected data and summing this data with the proper shading value.

Abstract: A high resolution scanning beamformer for a soundhead having a circular or a cylindrical array of hydrophones uses charge coupled devices as transversal filters in a plurality of first stage quadrature sampled phase shift steered beamforming modules. In a second stage, serial-in/serial-out charge coupled devices are used to correct for fill time. The sonar focuses at all nearfield ranges of interest by controllably varying a clocking rate.

Abstract: An ultrasonic transducer arrangement having ultrasonic oscillators, with which electronic delay chains are associated, includes a matrix of column-like ultrasonic oscillators the end faces of which are each connected to control electrodes arranged in the planes of the flat sides of the matrix. On one flat side of the matrix, rows of the oscillators are each provided with a common control line and, on the opposite flat side of the matrix, the jointly controlled groups of ultrasonic oscillators each form a concentric arrangement. This test head can be used selectably as a focusing or as an angle test head and in addition, the focal point can also be displaced in depth.

Abstract: A system for determining the direction of an underwater discrete source of acoustic vibrations by sensing acoustic wavefronts produced thereby, which system comprises a neutrally buoyant semirigid underwater platform which may be made of a water inflated soft walled material and having mounted thereon an array of omnidirectional hydrophones arranged in a predetermined geometric pattern. Circuit means are connected to the hydrophones and an array steering means is associated with the circuit means to allow determination of the time relationship of the signals obtained from the hydrophones.

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: Formation of channels for all-round passive sonar systems by the technique of charge-coupled devices. The shift register receives the multiplexed signals of the M transducers forming the listening base of the sonar system. The shift register has different series of sub-contacts, each series corresponding, at one moment, to the signal of one of the transducers. The adding of the weighted signals of one series gives an interpolated signal of the corresponding transducer. The such obtained delayed signals are weighted and added, such obtaining the preformed channels.

Abstract: Apparatus for determining the bearing of an acoustic source from a selected ocation in an acoustic environment includes a plurality of discrete acoustic sensor elements and a flexible member, having first and second ends, which may be deployed in a linear configuration in the environment. The sensor elements are attached along the flexible member in spaced apart relationship, one of the elements, comprising a lead element, being closer to the first end than any of the other elements. A motion measuring device is coupled to the lead element when the flexible member is deployed in the environment to generate signals which indicate the velocity of the lead sensor element in the environment.

Abstract: A beamformer for an array of sonar transducers, or electromagnetic radiating elements, includes mixers for translating the signals received by the transducers to a lower frequency. The beamformer incorporates delay lines operating at a clock rate which is reduced in proportion to the decrease in frequency. Each delay line provides delays to the signals of corresponding ones of the transducers in accordance with the time of arrival of a wavefront of radiation upon the respective transducers. Phase shifters coupled between the mixers and the delay lines impart phase shifts to the transducer signals proportional to the respective delays to compensate for the lowering of the frequency.

Abstract: A system for determining the location of a seismic wave source in a homogeneous medium (the soil) comprises a linear array of equispaced sensors sampled by respective pulse extractors in turn feeding a plurality of cascaded two-dimensional recursive digital filters which act as phase shifters estimating in small or incremental steps the magnitude of the wave field away from the sensor array. The output signals of the sensors are sampled at a rate equal to the ratio of the distance between the sensors and the wave velocity in the homogeneous medium, thereby giving rise to samples distributed in a single quadrant of the space-time domain. An attenuator connected in series with the phase-shifting filters damps frequency components outside the rotated quadrant, while an equalizer connected in cascade with the attenuator ensures a global linear response thereof.

Abstract: A parallel digital beam-former for an array of hydrophones. The output of ch hydrophone is fed into a different shift register. Each register stores the sampled time history of the hydrophone. The contents of each register are fed serially into a different gating circuit in the time interval between each new input signal sample and the output of each gating circuit is fed in parallel with the output of each of the other gating circuits to a group of beam gates. The output of each beam gate is then fed to a different binary counter which sums the signals. Each binary counter is associated with a different beam.

Abstract: Apparatus for forming one or more sonar beams in response to acoustic energy received by a transducer array. To minimize volume utilization, a plurality of CCD's are formed on an integrated circuit chip with the CCD's being of progressively smaller length. Half of the CCD array is folded over to match the other half so that each CCD has an opposing CCD with both CCD's propagating a signal toward a common output diode. By providing one integrated circuit chip for each desired beam with appropriately different clocking frequencies multiple beams may be formed, and with the provision of a variable clocking frequency, one or more beams may be steered.Transversal filter operations may also be performed by the apparatus.

Abstract: A beamforming apparatus is provided for processing the outputs of a linear rray of spaced apart receiving elements. The beamforming apparatus includes a surface acoustic wave device which has a pair of transducers mounted on a substrate in a spaced apart relationship. Each transducer is capable of receiving and converting an electrical chirp signal into an acoustic signal for propagation across the surface of the surface acoustical wave device. A plurality of taps are mounted on the substrate in a spaced apart relationship between the pair of transducers for receiving, sharing and converting the acoustic signals back into electric signals. Each tap is adapted to receive a bias voltage. A device is provided for mixing the signal from each tap with a signal from a respective receiving element so as to produce a plurality of mixed output signals, and another device is provided for summing the mixed output signals so as to provide a summed output signal.

Abstract: A passive ranging system is disclosed wherein the transducer array has its eam pattern modulated so as to match the arrival angles of the different wave fronts arriving at the array from various target distances. The beams are formed by orientating a multiplicity of readout arms at appropriate angles with respect to a recording medium which has the individual signals detected by each transducer of the array recorded thereon in different horizontal tracks. The readout arms thus simultaneously scan all of the signals associated with the arrival angles for a particular range and produce a signal whose amplitude is a measure of the probability of a target at this range.

Abstract: A serial phase shift beamformer characterized by a charge transfer device for progressive clocked transfer of quadrature component analog samples of the scanned outputs of a multiplicity of transducer elements in a curved array. Weighting resistors effect scaling of the analog samples during parallel readout of X and Y component samples prior to summation of like components and derivation of the square root of the sum of the squares of the X and Y summations to provide formed beam amplitude signals.

Abstract: A beam-former for sampling and digitizing a sonar signal preparatory to F Fourier Transformer (FFT) processing comprising an array of ceramic sensors forming a series of rows and columns, a sampling transformer for each row and each column for sampling the weighted sum of the signals from the sensors in each row or column, a log compressor for each sampling transformer for compressing the amplitude of the sampled signal, an analog-to-digital (A/D) converter circuit following each log compressor for sampling and digitizing the compressed signals under the control of a counting circuit so that the log compressor outputs are sampled at prescribed times in relation to each other so as to impart a time or phase shift to the digitized outputs to effect a beam tilting, a decompression circuit for decompressing the time shifted signals, an accumulator for adding the samples from each row and column, and a shifting circuit for shifting the accumulated signal up or down to make it compatible with the FFT circuit.

Abstract: An arrangement is provided for locating and identifying objects using holographic techniques. Improvements are achieved by array configuration and particularly with the use of a plurality of arrays to provide different types of information related to the same object. In one embodiment, a high resolution narrow field-of-view array is provided in combination with a low resolution wide field-of-view array. The low resolution array resolves the ambiguity for object location and the high resolution array permits object identification; wherein the combination of a high resolution narrow field-of-view array and a low resolution wide field-of-view array provides significant advantages over the conventional high resolution wide field-of-view array.A general purpose high resolution wide field-of-view array may be provided for obtaining desired information. In a mode requiring high computational rates, portions of the general purpose array may be selected to provide specific information.

Abstract: 1.

Abstract: 1.

Abstract: A sonar apparatus incorporating steered time compressor means for time coessing and steering hydrophone information. Novel control circuitry enables time compressing and steering operations to be performed in a single storage device.

Abstract: A transducer array is provided with omni-directional transducers, bi-directional transducers, and a processor which forms omni and bi-directional beams that are combined to cancel image lobes to give the array a uni-directional characteristic in which but a single, steerable main lobe is formed over a broad range of steering angles.

Abstract: A beamformer forms a beam from a set of samples of signals from an array of elements such as sonar transducers. Sequences of signal samples from each transducer are delayed relative to each other by fractional amounts of the intersample interval. The sequences of the signal samples with the predetermined delays therebetween are applied to a common beamforming filter having a pass band of sufficient width to accommodate the signals. The impulse response time of the filter is longer than the intersample interval in any one of the sample sequences for providing a beam equal to the sum of regenerated transducer signals. The radiation pattern of the beam is independent of the sampling rate.

Abstract: Forming and directive control of the beam in a circular sonar array without ime delay or phase shift networks. Predetermined weighting coefficients are used to scale sensor outputs that are summed in an add-only processor to provide a weighted sum output characteristic of target position relative to the main receiving axis of the array.