Abstract: In the fish sonar, the temperature and the hydrogen ion exponent in the sea are recorded or displayed on the recording medium or display of the recording or displaying device with digital echo signals of an ultrasonic wave corresponding to a base line, a school of fish and the bottom in the sea. The fish sonar need not have an exclusive device for measuring temperature and hydrogen ion exponent in the sea.

Abstract: This invention is of an ultrasonic proximity switch having a range selection control circuit. The range selection control circuit is in this instance separated from the sensor by being installed in a separate housing which can be mounted in the switching unit. It is equipped with a potentiometer in the form of encoding switches and an actual value display which can be designed in the form of an LCD design. In addition, various selector switches can be mounted in the housing.

Abstract: A method and apparatus for remotely activating and analyzing fiber optic ed and conformal sensor arrays using fiber optic transmission and reception with multiplexed input and output signals using optical wavelength division, electronic frequency division, or both.

Abstract: A circuit automatically determines the nature of the seabed over which a vessel is passing, indicating via an audible or other warning signal when a fishing vessel is above a type of seabed which might damage the fishing net. The circuit is responsive to an echosounder signal and raises an alarm when a amplitude of the second bottom echo component in the echosounder signal exceeds a selected threshold level. Preferably the analog echosounder signal is subject to threshold discrimination to provide a pulse-form signal which is then processed by a digital logic circuit to isolate the second bottom echo component.

Abstract: A method for troubleshooting an underwater acoustic transducer array comprising a plurality of transducers so as to test the operationally installed underwater transducer array on board for its operational reliability and to be able to localize malfunctioning transducers. For this purpose, a sinusoidal test signal, preferably the transmitted signal itself, is fed through a connecting line into the transducer array from a location remote from the transducer array and the current flowing through the transducers is detected by at least two samplings as the real component and the imaginary component with respect to the test signal. The sampling values are transmitted back to the remote location and the admittance of each transducer is determined from the ratio of the real component and of the imaginary component of the current to the test signal amplitude. A significant deviation from the known admittance at the test signal frequency is interpreted as a transducer malfunction.

Abstract: An acoustic device for eliciting either attraction or repulsion behavioral responses in fish comprises a water tight enclosure having a radiating surface rigidly supported in one end thereof. Drive means for the radiating surface are provided with the capability of causing the radiating surface to vibrate at its resonant frequencies so that an acoustic signal is generated capable of a peak sound pressure level of at least 0.5 kPa (0 to peak) at a distance of 3 meters from the radiating surface. The signal generated has one fundamental frequency component in the range 20 to 1000 Hz and a plurality of resonant and harmonic frequencies associated with said fundamental frequency. The drive means, radiating surface and enclosure coact to generate an acoustic signal having characteristics such as resonant frequencies, peak pressures and temporal patterns which may be selectively optimized to produce the desired behavioral response.

Abstract: A computer system is proposed for finding and displaying the depth and depth related values of an object in an aquatic environment in which and LCD display is subdivided into segments each representing a fraction of the total depth range in which the system is operating as well as a fraction of the transit time for the transmission of pulses within the depth range. Each segment is addressed and activated in response to the presence of a receiver output in the microprocessor for a given number of consecutive time-scans, thus providing a quasi-analog visual display of depth on the array of the segmented scale.

Abstract: Method and apparatus for identifying a number of people in a monitored area wherein a first reflected ultrasonic wave map of the monitored area is collected that includes background objects. A second reflected ultrasonic wave map of the monitored area is collected when people may be present in the monitored area. The first collected background defining map is subtracted from the second collected map to obtain a resulting map. The resulting map is processed to identify clusters having a minimum intensity. A cluster size of the thus identified clusters is utilized to identify clusters corresponding to people. The ultrasonic detecting method and apparatus is utilized with a wave signal receiver for identifying an audience composition of the receiver and determining the viewing habits of the public.

Abstract: A display system for fish sonar displays two ultrasonic echo signals of different frequencies from the left side to the central portion and from the central portion to the right side on the screen of a cathode ray tube. After the two ultrasonic echo signals are displayed on the entire screen of the cathode ray tube, the old echo signals are eliminated and the display is refreshed with new echo signals so that a picture of a school of small fish which is displayed by ultrasonic echo signals of high frequency can be compared with a horizontally adjacent picture of a large fish simultaneously displayed by ultrasonic echo signals of low frequency on a single cathode ray tube screen.

Abstract: The acoustic characteristics, particularly the attenuation coefficient, internally of a object undergoing examination are measured on the basis of ultrasonic echo pulse, and diminishing the influence of the sound field. Standard media having attenuation coefficients that differ from one another are measured in advance by a predetermined method to find the attenuation rates and attenuation coefficients thereof. The attenuation coefficient of the object is taken to be the attenuation coefficient of one of the standard media that minimizes a difference between the attenuation rate of each standard media and the attenuation rate of the object, which is measured based on an ultrasonic echo signal from within the object.

Abstract: Three or more listening devices (A1, A2, A3) are dispersed over the water area where the location of a sound source is to be determined, and transmit radio signals over respective channels to a master station upon detecting sound. The master station correlates the signals from selected ones of the listening devices to derive the position of the sound source relative to those listening devices. If the positions of those listening devices are unknown, for example if the devices are floating free, their positions are determined by the master station by comparing the relative times at which an identifying radio signal transmitted by each listening device is received by the master station directly and relayed from each of two stationary radio stations with known positions. The listening devices may also be provided with receivers for receiving radio command signals from the master station, for example relating to activation of certain listening devices and assignment of radio channels.

Abstract: A sound transducer mounted inside a buoy for broadcasting sounds both underwater and above water. The buoy is a hollow sphere which admits water; but whose buoyancy is maintained by air-filled balls or a bladder captured inside.

Abstract: The device comprises at least two ultrasonic transducers emitting focused radiation and a circuit making it possible to measure the difference between the sampled signals supplied by these two transducers. This difference is cancelled out when the probe faces the object.Application to metrology and the position control of objects.

Abstract: A portable, self-contained underwater signalling device adapted to be worn by a diver. A waterproof housing has contained therein an acoustic sound generator, a power source and a three-position switch and circuit board connected in circuit between the power source and sound generator. The three-position switch provides an off or open position, a momentary on position and a full on position. The circuit board may vary the frequency of the signal output of the sound generator when the switch is in the constant on position to generate a pulsed frequency or a constant frequency.

Abstract: In ultrasonic transmission from and reception by an array probe in a phased array sonar, when an ultrasonic beam is directed substantially in front of the array probe, an ultrasonic wave having a high center frequency f.sub.o, or a bandwidth extending into higher frequencies, is transmitted and/or received in order to insure a high image resolution. When the ultrasonic beam is steered sideways, an ultrasonic wave having a lower center frequency f.sub.o, or a higher frequency range cutoff in relation to a steering angle .theta., is transmitted and/or received in order to increase the angle at which grating lobes are generated and hence prevent such grating lobes from entering the angle range of the field of view.

Abstract: This invention relates to an acoustic energy absorbing material which abss sound energy underwater and its performance is independent of the surrounding hydrostatic pressure. It consists of a non-conducting elastomeric matrix having piezoelectric or magnetostrictive particles disposed therein for converting incident soundwave energy into heat, a corrosion resistant coating on the particles for optimizing energy absorption of sonar waves of predetermined frequency, the elastomeric matrix designed so as to have a Poisson's ratio of about 0.5 for effectively utilizing all particles so the incident soundwaves are applied to the particles as a hydrostatic stress distribution, and the acoustic energy absorbing material consisting of a plurality of thin layers of the elastomeric matrix and having high energy absorption per unit volume for providing a slight impedance mismatch between successive layers thus absorbing the predetermined energy of the soundwaves.

Abstract: An apparatus for detecting obstructions behind a vehicle, employing ultrasonic waves is disclosed. The apparatus comprises an ultrasonic transmitting and receiving device disposed on the rear portion of the vehicle, an electric motor for rotating the transmitting and receiving device at a constant velocity, an angle sensor for detecting the rotating angle of the transmitting and receiving device and a sonar circuit for emitting ultrasonic waves through the transmitting and receiving device at predetermined rotating angles, receiving ultrasonic waves reflected from obstructions through the transmitting and receiving device at predetermined rotating angles and measuring the distance to the obstructions from the time taken from the transmission to the reception of the ultrasonic waves.

Abstract: A sonar system for indicating the presence of sonic energy reflecting interfaces in the water in the path of a downgoing sonic pulse. The received reflection or echo is recorded on a moving record or web by means of a stylus that is traversed across the web as a linear function of time. The movement of the stylus triggers the transmitted pulse and the received signal is then amplified and controls a high voltage source which generates a series of pulses applied by the stylus as it moves across the record. Under certain operating conditions there is considerable noise generated in the water by the sonic pulse due to the presence of many reflecting surfaces from sediment, algae, plankton, etc. which sustains the return signal to the transducer. A disable system is provided which on command of the operator will disable the operation of the transmitter and receiver on alternate operating cycles to provide time for this noise to attenuate.

Abstract: Method and apparatus for surveying positions of mooring lines extending between a moored structure and anchors in the water bottom comprising a rotatable submarine transducer assembly including acoustic pulse transmitting means and an array of acoustic receivers, a support for locating the transducer assembly at a predetermined level above the water bottom and actuator means for rotating the assembly about a vertical axis relative to the support. During operation the transmitting means produces a beam of acoustic pulses. Pulse reflections originating from mooring line sections that are successively scanned by the beam are received by the acoustic receivers, and the position of each scanned mooring line section is calculated by a processor unit on the basis of the time interval at which the pulses are received after transmission.

Abstract: A method of and apparatus for locating an object by stress wave energy reflection in which the wave energy is transmitted as a beam by transmitting transducer elements, and is scanned through successive sectors of a field of view by imposing differential transmission delays on transmitting signals fed to the elements by means of a delay line. Indicator signals are developed in receiving channels connected respectively to receiving transducers providing binaural characteristics, and transducer providing monaural characteristics but collectively covering the field. An indicator means comprises any, or any combination, of audible means, visual means or tactile means the two latter providing coordinate displays.