Abstract: An apparatus for detecting the position of an object with an ultrasonic wave includes a timing control circuit generating first and second timing signal trains, the interval of the first timing signal trains being set to be shorter than that of the second; an ultrasonic wave pulse generator circuit generating first and second ultrasonic wave pulses in synchronism with the first and second timing signal trains, the first ultrasonic wave pulses covering a short distance range to the object and the second ultrasonic wave pulses covering a long distance range to the object, the width of the first ultrasonic wave pulse being set to be shorter than that of the second. An ultrasonic wave pulse transmitter transmits alternately the first and second ultrasonic wave pulses; a receiver receives the reflected first and second ultrasonic wave pulses from the object; and a discriminator circuit discriminates the reflected first and second ultrasonic wave pulses from the receiver.

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: Apparatus which provides both range and bearing information between a transponder and a transponder interrogator. The interrogator transmits an acoustic interrogating pulse which is received by the transponder and in response thereto transmits back a first signal of a certain frequency f1. Two spaced apart hydrophones on the transponder provide their respective output signals to a phase meter, the output signal of which is indicative of the direction, that is, bearing, from which the interrogating pulse impinged. The phase meter output is converted to a corresponding time delay after which a second signal of a frequency f2 is transmitted. A counter in the interrogator starts counting upon transmission of the interrogating pulse and stops upon reception of the first signal of frequency f1. A second counter of the interrogator starts its count when the first counter turns off and terminates its count when the second signal f2 is received.

Abstract: An electronic diving apparatus detects pressure by means of a bellows transducer (12). A variable frequency oscillator (10) produces a variable frequency output in proportion to the pressure applied to the transducer (12). A local oscillator (16) produces a fixed frequency signal which is mixed with the variable frequency signal in a mixer-demodulator (14) to produce an audio depth signal. The audio depth signal is provided to up/down counters (30). A time base and synchronizer circuit (24) sequences the counters (30) for an up frequency count and a down frequency count of the audio depth signal. When the difference count exceeds a preset limit, a maximum rate of depth change circuit (34) produces an alarm signal which is transmitted through a beep timer circuit (36) to activate an audio driver and output circuit (28) which produces alarm signal at an audio disk (38). This gives a warning of too rapid of an ascent or descent by the diver.

Abstract: A method for synthesizing arbitrary broadband signals for a parametric ar which computes the input waveform needed to a parametric array source to obtain a received signal of a prescribed waveform. The method uses Fourier transform and the inverse transform of digitized received signal in order to make computation in either the frequency domain or the time domain depending upon the computational simplicity in a particular domain. The method uses a iterative process to obtain the received signal very close to the received signal of the desired waveform.

Abstract: An apparatus for determining an angle of incidence of a received signal utilizes two widely spaced interferometers with equal length crossing baselines. The time differential of a signal arrival between the two elements of each interferometer is established and the difference between the two time differentials is determined. Multiplying this difference by a predetermined constant provides the desired angle.

Abstract: A depthsounder for selectively measuring either bottom depth or the depth of any fish located beneath a vessel. When operating in a depth mode, the depthsounder automatically adjusts the gain of its receiver to minimize interference and provide a filtered display of bottom depth. When operating in a fish finding mode, the depthsounder likewise automatically adjusts the gain of its receiver to minimize interference in its detection of fish. In addition, the depthsounder suitably processes any return pulses to distinguish those produced by fish from those produced by other objects in the water. When fish are detected, the depthsounder provides a visual display of their depth and an aural alarm whose repetition rate is proportional to the number and size of the fish.

Abstract: An acoustic transducer is connected to an electronically controllable time-dependent conductance so that energy may be rapidly applied to and extracted from the transducer and associated circuitry.

Abstract: An interferometric sonar in non-linear acoustics for high-resolution observations of objects located in the vicinity of the sea floor includes two end transducers for simultaneous transmission at two high frequencies F.sub.1 and F.sub.2 of the order of 200 kHz. Reception is performed by hydrophones placed between the sending transducers at the low frequency F.sub.2 -F.sub.1 of the order of 20 kHz. Angular channels are formed during two transmission sequences. Transmission takes place in phase at the frequency F.sub.2 -F.sub.1 in one sequence and in phase opposition in the other sequence in the case of the two sources generated by non-linear effects.

Abstract: A method and device for attenuating wideband spurious noises to improve the signal-to-noise ratio of a tracked acoustic signal. Two sensors (1 and 2) are provided, one of which receives the disturbed tracked signal and the other the spurious noises, to feed a plurality of correlation modules (4) via as many spectrum-line filters (3) distributed throughout the useful bandwidth of sensor (1), each of said correlation modules (4) supplying a correction signal and the sum of said correction signals being subtracted from the signal given by sensor (1) to yield a noise-free tracked signal. The invention is applicable to acoustic reception systems used in noisy environments.

Abstract: A sound source searching device for searching an objective sound source out of a plurality of sound sources, is disclosed. The device comprises an intensity probe provided with one pair of microphones, pulse motors for rotating the probe on the horizontal and vertical planes, a computer for calculating acoustic intensity corresponding to the frequency of the objective sound source from the sound pressure signal generated by the intensity probe, an interface device provided with pulse motor driving circuits for driving the pulse motors in accordance with the instructions of the computer by predetermined angles and an indicator for indicating the direction in which the acoustic intensity is the minimum on the horizontal and the vertical planes, as the direction of the objective sound source.

Abstract: An array device having a plurality of stacked circuit boards, each having a recess in a flat side thereof which extends parallel to a narrow side; the recess containing electronic components. Control lines for the electronic components are arranged on a flat side of the circuit board. Each circuit board has a narrow side which is provided with electrodes which are ordered as a matrix in rows and columns. The electrodes of the circuit boards are each associated with a respective switchable amplifier. The switchable amplifiers are arranged one behind the other in the longitudinal direction of a recess, and are connected by respective conductors having substantially equal lengths for coupling the switchable amplifiers to their respective electrodes. A plurality of main control lines are arranged on the narrow sides of the circuit boards for connecting the control lines of the switchable amplifiers in the same column to one another.

Abstract: A sonobuoy float canister is releasably latched to a wound cable pack container. The cable is attached at its upper end to the canister and at its lower end to a lower sonobuoy component. A rotor latches the canister and container together in one rotative position so that the cable is not unwound or payed out to provide a first or shallow depth deployment of the lower component. In a second rotative position of the rotor the canister and container are unlatched from one another and the cable is positively restrained after a predetermined partial payout to provide a medium depth deployment of the lower component. In a third rotative position of the rotor the positive restraint of cable payout is removed and the canister and container are unlatched so that the cable is fully payed out to provide for full depth deployment of the underwater component.

Abstract: Acoustic distance measuring apparatus for measuring the distance of a vessel (N) from a vertical line through a fixed point (P) on the bottom of a body of water, the apparatus comprising: an acoustic emitter unit (I) and at least three acoustic receiver units (H1, H2, H3) disposed on the bottom of the vessel, said receiver units being disposed at the vertices of a plane polygon; at least three acoustic emitter/receiver units (A, B, C) placed on the water bottom in the vicinity of said fixed point (P), said emitter/receiver units being disposed at the vertices of a polygon; and the improvement wherein the measuring apparatus further includes a relay acoustic emitter/receiver (R) submerged close to the vessel at a depth where vessel noise is highly attenuated, said relay receiing acoustic waves (a) from the vessel's emitter and responding by emitting acoustic wave (1, 2, 3) to the vessel's receiver units thereby enabling the distances between the relay and each of the vessel's receiver units to be calculated, s

Abstract: An adaptable filtering device and method for filtering sonar signals to remove reverberation signals caused by the vehicle speed and trim and the sea surface and sea bottom. The vehicle itself has an antenna for transmitting and receiving sonar signals, a speed detector, a trim detector, a depth detector, and a distance-to-sea bottom detector and a sonar output device. The present invention forms paths corresponding to each distinct direction from which sonar signals are received by the antenna, each path having a path signal B.sub.i. For each path, a calculation is made to determine a central Doppler-shift frequency .DELTA.f.sub.i and a cut-off frequency f.sub.c.sbsb.i which are to be used to filter the path signal. This calculation is based upon the detected vehicle speed, the detected vehicle trim, the detected vehicle depth, and the detected distance between the vehicle and the sea bottom. The calculated frequencies .DELTA.f.sub.i and f.sub.c.sbsb.

Abstract: An improved method and apparatus for measuring the length of an open pipe includes a sound transducer placed in spaced open air communication with the interior of the pipe at a selected end. A logic circuit is employed with the transducer for producing a square wave sound pulse that is directed at the pipe's selected end. An oscillator provides an ambient temperature modified count in accordance with the time required for the pulse to travel the length of the pipe and return. For compensating for error tending to be introduced because of the spacing of the impedance reflective surface at the far end of the pipe, a standoff device establishes such a distance between the transducer and the selected end of the pipe as to effect an adjustment in the duration of the oscillator count that corrects for the error.

Abstract: In an ultrasonic distance measuring apparatus producing distance data representing a distance to an object by transmitting and receiving an ultrasonic wave, a sensor detects variation in the temperature and/or humidity of the atmosphere, and a compensator compensates for variation in propagation characteristic of the ultrasonic wave caused by the variation in the temperature and/or humidity respectively.

Abstract: An apparatus and method for detecting the direction of a sound. A thin shell structure is permitted to flex in response to incident sound and perturb the form of the shell. The perturbation is detected and from this the direction of the sound can be determined.

Abstract: An ultrasonic detection circuit for detecting obstacles behind a backing motor vehicle, and an ultrasonic communication circuit are automatically switched such that the ultrasonic detection circuit is operable only when the communication circuit is not in use. Furthermore, the ultrasonic detection circuit may be operated only when the motor vehicle is in one or more particular operating conditions. The system comprises a rear ultrasonic transducer used for both the detection circuit and for the communication circuit so that detection of obstacles behind the vehicle and communication with another motor vehicle behind the vehicle are possible, and a front ultrasonic transducer used for only the communication circuit so that communication with another motor vehicle ahead of the vehicle is also possible.

Abstract: A single transducer ultrasonic distance sensor is disclosed which provides for range sensing down to zero distance from the sensor housing envelope with an electroacoustic transducer subject to unavoidable ringing following emission of a burst of acoustic energy. The housing is configured and the transducer mounted therein so that an acoustic path at least half as great as the distance travelled by an acoustic signal during the transducer ringing interval is provided within the housing envelope.