Abstract: An automatic attenuator for use in Sonobuoy Missile Impact Location System (SMILS) sonobuoys to separate re-entry which impact signatures from other acoustic phenomena is disclosed. The attenuator for the sonobuoy device is divided into a high gain, narrow band channel for detection of ping signals and a low gain, wide band channel for detection of impact signals. The output of the two channels are summed in a summing amplifier. A switch is provided to turn off the high gain channel whenever received signals are large enough to cause a comparator circuit to activate a time which turns off the switch for 15 seconds time. Thus, the stronger impact signals are distinguished from other random signals.

Abstract: In a color sonar system especially suitable for displaying fish echo signals, high and low frequency echo image signals are displayed utilizing colors corresponding to the echo signal strength, when the signal strength differences between the simultaneously received high and low frequency echo image signals are within a preset level range, when the differences between the high and low frequency echo image signals are outside the preset level range, the selected high frequency or low frequency echo image signals are displayed utilizing colors indicative of the differences in signal strength between the corresponding high frequency and low frequency echo signals.

Abstract: A speed measurement device for measuring the speed of a ship through the water is disclosed. The device comprises a transmitter circuit and a receiver circuit connected to two transducers T.sub.1, T.sub.2 which are based substantially in the direction of travel of a ship below the water line thereof. Pulse trains are transmitted in both directions between the transducers T.sub.1, T.sub.2 which are received by the receiver circuitry so that a signal is derived indicative of the time taken for the signals to travel both for and against the direction of travel of the ship, this signal being proportional to ship's speed.

Abstract: A low cost, effective electronic audio aid for the blind who have good hearing. The aid employs a hand held housing about the size of a flashlight which contains a battery power supply and electronic-audio circuit together with a somewhat directional audio speaker for emitting a low power, directional beam of acoustic energy having specially-shaped audio waveforms which when impinging on an object in the vicinity of the user return an altered, reflected characteristic sound signal which can be audibly discerned by the user to detect the presence of the object and its approximate location.

Abstract: An underwater communication system of the present invention comprises a transmitter including message inputting means having keys, each being assigned to each word, code converting means for converting a key input entered through the inputting means to a code assigned to the key input, modulator means responsive to the code for performing modulation, and transmit transducer means for converting an output of the modulator means to an acoustic wave, and a receiver including a receiver transducer means for reconverting the incoming acoustic wave from the transmitter to an electric signal, demodulator means for demodulating the electric signal to generate the code, speech synthesis means responsive to the demodulated code for producing a word corresponding to the code as a speech, and speaker means for outputting the synthesized speech.

Abstract: A keyboard apparatus has a plurality of elastically deformable elastic members disposed on a board in a predetermined positional relationship, a plurality of push members each disposed above each of said plurality of elastic members and adapted to push said elastic member to cause the same to elastically deform and produce an acoustic signal. At least three pickups are disposed on the board at different positions for sensing arrival of the acoustic signal. A detecting circuit determines for detecting the keyed position in response to the output from each of the pickups based upon the differences between arrival times of the acoustic signal at these pickups.

Abstract: A method and device for improving the restoration of the images obtained from samples taken from acoustic signals received by a lateral aimed sonar provides for the selection of samples from the signals received, the time interval between the samples selected being smaller at the beginning of the echo reception window than at the end thereof so as to improve the power of resolution of the sonar for directions of low obliqueness. The sampling may be carried out at a variable frequency or else at a very high fixed frequency, the selection then being made among all the samples obtained.

Abstract: A plurality of ultrasonic transmitting elements and ultrasonic receiving elements are provided and are electrically switched in a sequential manner to change a region over which the existence of an object is to be detected, thus allowing the existence of an object to be detected over an extended range. The distance to the object and a particular region in which it is detected are displayed. The ultrasonic transmitting elements and the ultrasonic receiving elements are alternately disposed in a linear array. When switching the region over which the existence of an object is to be detected, the switching of the ultrasonic transmitting elements takes place in an alternate fashion with the switching of the ultrasonic receiving elements, thus changing the region at an interval corresponding to one pitch with which the elements are disposed in the array.

Abstract: An ultrasonic wave signal having its frequency varied continuously is transmitted from an ultrasonic wave transmitter toward a moving body. The wave reflected from the moving body is received by an ultrasonic wave receiver, and the resulting signal is frequency-demodulated to obtain a signal representing a frequency variation. A signal representing the feature of the moving body is produced with use of a signal representing the frequency variation of the transmitted ultrasonic wave and the signal representing the frequency variation of the received ultrasonic wave.

Abstract: An underwater detection system which has a transmitting and receiving unit for radiating an ultrasonic wave pulse into the water within a narrow sector and receiving echo signals by a plurality of reception beams, and turns the transmitting and receiving unit by a predetermined angle to search another narrow sector each time the search within the narrow sector is completed, thereby searching the water within a wide angular range.

Abstract: An apparatus for properly aligning a cathode-ray tube projection unit before a viewing screen includes a pair of ultrasonic rangefinders and a cooperating pair of light emitting diode (LED) reader units. One ultrasonic rangefinder and one reader unit are connected to each of two opposite sides of the projection unit. Each rangefinder is directed toward the viewing screen to sense the distance between the viewing screen and the side of the projection unit to which the rangefinder is connected. The cooperating LED reader unit then indicates whether that side is too close to, too far away from or a proper operating distance from the viewing screen.

Abstract: A circuit arrangement for separating high-frequency pulses produced successively in time at a piezoelectric transducer of an acoustic reflection lens arrangement. According to the invention, the transducer is preceded by a three-way pin switch, the common end of the wiper of which is connected to the acoustic lens, the other end of the wiper being alternately connected in a first position to the output of a transducer oscillator, in a second position to a 50-Ohm resistor, or in a third position to a measurement circuit.

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: In combination, intrusion detection apparatus giving a signal when a light vehicle approaches a geophone, and a heavy vehicle discriminator disabling the detection apparatus when the approaching vehicle is a heavy one.

Abstract: A bellows assembly to house and shield an electrical cable, and a connector attached thereto, from the effects of an electromagnetic pulse. The assembly includes: an expansible and contractable cylindrically shaped, flexible, bellows-like component made of magnetic material, having open ends, and with convolutions along its surface perpendicular to the axis of its length; a rigid transition cover made of magnetic material, having two apertures shaped to permit the passage of the electrical cable and connector attached thereto, positioned at one end of the bellows-like component; and, a spring-type clamp to attach the transition cover, at one of its openings, to one end of the bellows-like component. The other end of the bellows-like component is grounded.

Abstract: An ultrasonic transducer assembly incorporating an ultrasonic transducer and conically surfaced beam transformer wherein the conical surface of the beam transformer is mounted on the interior of closure means or end cap that seals the transducer (and any associated mechanisms) from the environment during non-operating periods and is moved into the prescribed position via rotational motion or a linear piston-like motion prior to operating periods. Suitable O-ring or gasket sealing means preserve the water tight integrity during non-operating periods and assures a seal during translational movements of the transducer assembly from operating to non-operating positions. On school buses, the beam transformer is translated to an operative position below the bus where, in conjunction with a microprocessor, it takes an accurate acoustic image before the bus door is opened and again before the bus resumes forward motion so as to detect whether students have crawled under the bus while it was stopped.

Abstract: Sonobuoy parachute shroud line ends are retained by a cup mounted in and adjacent one end of the sonobuoy outer casing. A heavy ejection spring is beneath the cup for forcibly ejecting the cup outwardly from the one end of the casing. The cup is retained in the casing against the spring force by a pair of partially overlapping elongated plates each having one end releasably inserted in a circumferential slot in the outer casing, the slots being adjacent the casing one end and diametrically opposed. The upper plate is in retentive contact near the other of its ends by a first retainer rod pivoted at one of its ends to the cup bottom surface. The first rod contacts the upper plate near the pivoted rod end and is in retentive contact near its other end with a second retainer rod pivoted at one of its ends to the cup bottom surface. The second rod contacts near its pivoted end the first rod and is in retentive contact at its other end with a one shot spring motor driven pin.

Abstract: A method for measuring the running time of a signal transmitted by a transmitter and received by a receiver is devised, where the signal is transmitted and received by the same transducer. For transmitting the transmitter is driven by an electrical pulse train, and in receiving the received signal is converted back into an electrical signal. In receiving triggering is done on the trailing edge of the envelope of the received signal. At the transmitting side the transducer after its incitement is driven by a pulse train being in phase opposition to the original inciting signal and having a larger amplitude than the original inciting signal which results in a higher steepness of the envelope. At the receiving side the maximum amplitude is measured, and the triggering point of time is determined when the actually measured value of the envelope falls below a certain percentage value of the maximum value.

Abstract: A remote monitor unit comprising a battery pack, a regulated power supply, program control board, a receiver AD board, a plurality of memory boards and a transducer, all housed in a water tight enclosure. External control or data communication links are unnecessary with the remote monitor unit. Once the device has been activated and placed in its housing, a programmable time delay feature allows the user to place the unit at a selected site in advance of the start of the recording period without wasting any data storage capability. When deployed and activated, analog data from the transducer is converted to digital form and silently recorded by storing it in a non-volatile memory medium on the memory boards. The digitized information is later retrieved from the memory boards by micro, mini or main frame computer and stored on magnetic tape for subsequent processing. The memory boards are then erased by exposure to ultra-violet light and reused.

Abstract: The system is for determining the direction and/or distance of objects and, especially of watercrafts, by means of water-borne sound waves transmitted from the ship to a torpedo, for example. The system includes a cathode ray tube located on the ship for displaying sectors of interest, at least one storage means at the torpedo for storage and delivery of sound location data and being connected to a length of wire for transmitting stored location data over the wire to the ship, a controllable threshold discriminator connected to the storage means, and means for limiting the frequency bandwidth of data signals transmitted over the communication wire to an order of magnitude of 500 Hz.