Abstract: Undesirable or unpleasant audible sound otherwise generated in a conventional distance measuring apparatus is removed or minimized by controlling the waveform of a burst signal supplied to an ultrasonic transducer so that it has a substantially trapezoidal waveform changing in level with time at rise and/or fall portions thereof.

Abstract: An acoustic direction finding method utilizes correlation between the signals of plural sound pickups on a rotating base. As the base rotates the pickups receive signals from a source of sound which is the target for which direction information is to be obtained, these signals are shifted in time from one pickup to the next. The base is rotated substantially at constant speed with one full rotation being divided into a plurality of angle sections. The pickup signals are correlated in the individual succeeding angle sections, thus obtaining a correlation function with a correlation peak corresponding to the target direction for each angle section. The correlation functions of the same angle section are added to each other with successive rotations of the base. A curve generated by the correlation peaks is then smoothed and utilized to determine the direction of the target.

Abstract: A method of determining both the level of sound occurring at a point in an area of interest and the location of the point. The level of sound at a point in the area of interest is sensed, and a first signal is transmitted from the point. This first signal is received at a first location related to the area of interest, and the direction relative to the first location from which the first signal was transmitted is determined. A second signal is transmitted from the first location which is indicative of the direction relative to the first location from which the first signal was transmitted. Similarly, the first signal is received at a second location related to the area of interest. The direction relative to the second location from which the first signal was transmitted is determined, and a third signal is transmitted from the second location which is indicative of the direction relative to the second location from which the first signal was transmitted.

Abstract: A system for measuring the distance between two objects, for determining the center between two objects and for triangulating the height of a tall object. In measuring the distance between two objects, an initial count is started when a first ultrasonic pulse is transmitted. The initial count is stopped when that pulse is received. The second pulse is transmitted only after a delay interval where the delay interval begins at the start of the initial count and is substantially equal to the maximum range time of a transducer. The restarted count is stopped when the second pulse is received, and the resultant count is displayed as a number related to the total distance between the objects.

Abstract: A sonar survey apparatus comprises a submersible vessel having a structure adapted to receive a towing cable. A sonar signal transmitter is mounted on the structure. At least one acoustic reflector is mounted on the structure and is shaped to produce, in a focussing plane, line foci of acoustic echo signals received from remote positions. A line array of receiver transducers are mounted on the structure in the focussing plane and extend in a line substantially at right angles to the line foci. Each receiver transducer element has an output for providing a signal representative of a focussed echo signal. A selector is coupled with the output of each of the receiver transducer elements and has a control input and an output. The selector is operable in response to the control signal to select the output of a receiver transducer element, relating to a predetermined direction, for display.

Abstract: Method and apparatus for determining the distance from a preselected point to a target. An electrostatic ultrasonic transducer in a special protective housing is used with a single-pulse, square-wave transmitter to compare a main signal with a calibration signal. A warning signal indicates when the number of signals actually received during each one hundred signals sent drops below a predetermined percentage. Noise is minimized by careful spacing and shaping of the calibration bar and by insulating foam in the housing.

Abstract: The disclosure is directed to an apparatus for determining position in a data space. A generally flat tablet is provided, the tablet being formed of a solid acoustically-conductive material. A movable element, such as a stylus, is adapted to be manually movable over the tablet surface, the movable element having a tapered tip which contacts the surface of the tablet. An acoustic transducer is coupled to the tip of the movable element. Fixed transducer means are coupled to the tablet. Means are provided for energizing acoustic energy to propagate in either direction between the transducer of the movable element and the fixed transducer means. The midrange frequency of the energy is selected such that the wavelength of the energy mode propagating parallel to the tablet surface is a function of the tablet thickness. Means are provided for determining the time of propagation of the acoustic energy travelling, in either direction, between the transducer of the movable element and the fixed transducer means.

Abstract: A pseudo-random noise generator (PRNG) or a hard clipped tonal is remotely mployed as an acoustic signal simulator for calibrating individual hydrophone channels of an acoustic array. The PRNG is employed to present a complete measurement of the channel gain and phase vs. frequency characteristics. The circuitry provides for synchronizing a channel hydrophone PRNG's to obtain gain and phase comparison of a single channel measurement. The hard clipped tonal provides the gain vs. frequency of the channel transfer function. In addition a binary signal is provided for changing the gain of the channel.

Abstract: An underwater communicator device (10) is disclosed which permits acoustic communication with another diver by use of a voice synthesizer (42) cooperating with an acoustic transducer (40). A display (34A) is also provided to visually communicate the message. The keyboard (18) of the device (10) permits the diver to communicate stored messages by activating a single key 54 or to enter a complete arbitrary message by keying in the actual message. In other forms, the device (10) can include an air pressure transducer (60) for monitoring air tank pressure with a warning of low pressure. A depth pressure transducer (64) can be incorporated into the device (10) to monitor the depth of the device and diver. A bottom timer can be incorporated within the device for measuring the time of the depth. These functions can be continuously displayed to the diver on display screen 34B.

Abstract: A method and apparatus for underwater ranging with the aid of sonic pulses, by irradiating a given transmitting area with sonic energy pulses from a transmitter mounted in a marine vessel, receiving sonic energy echoes reflected from bodies in the transmitting area in a manner which is selective with respect to direction in a plurality of receiving sectors arranged in a fan shape, and associating the received echoes with respective reflection centers within the respective receiving sectors on the basis of associated sonic pulse travel times. Reception is carried out on a second marine vessel different from the vessel carrying the transmitter and which travels at a rearward offset position from the vessel carrying the transmitter at such a distance therefrom that the receiving sectors cover at least part of the given transmitting area, and the azimuthal width of the transmitting area is made very small.

Abstract: The position of a submerged object towed at great depth from a ship is determined, with respect to the ship, from measured values of the travel time of acoustic pulses between the ship and the object. These pulses are emitted at different locations of the ship and received at a point of the object. The values of the travel times of the pulses are measured and digitized on the object and transmitted by cable to the ship where they are processed, in combination with values representing the distances between the emission locations, to determine the coordinates of the object with respect to a system of axes associated with the ship.

Abstract: A passive method for obtaining target data from a sound source disposed in a nonsolid medium by means of a sound receiver remote from the sound source, by the steps of: providing, as the sound receiver, first and second sound-to-electrical signal transducers constituted and positioned to each respond to a respective one of two sound waves propagated from the sound source to the sound receiver at respectively different propagation speeds; and deriving, by means of an electrical signal processing system connected to receive output signals from the transducers, target data from the sound source by determining the frequencies of, or the difference in reception time between, the sound waves emitted by the source and to which the two transducers respond.

Abstract: A sonic ranging and/or object detection system, particularly useful for the blind, periodically employs widely different pulse frequencies in order to distinguish between objects located directly in front of the energy transmitting portion of this system and those located to either side. The higher frequency pulses produce a relatively narrow sonic energy beam width for detecting centrally located objects and the lower frequency pulses produce a relatively broad sonic energy beam width for detecting lateral or off-center objects. One or more time-related audible tones are superimposed on each of the pulse frequencies for range determining and/or object distinguishing purposes.

Abstract: Sonar apparatus provided with a beamforming network (1) containing several receiving channels (4A-M) for supplying, for each direction of beam incidence, digital composite signal products obtained by superposition of the receiving channel output signals and for transforming the signal products to a low-frequency band. The signal products are fed to a signal analysing circuit (3) comprising blocking circuits (62 and 63), and to a noise detector (61) for deriving, for each direction of beam incidence, a blocking circuit control voltage from the interference signal components in the signal products. The noise detector selects signals outside the low-frequency band part representing the transmitting/receiving band, and determines the modulus of the filtered signals and the average value thereof. The modulus and, after thresholding, the average value are fed to a comparator (77) to generate the control voltage.

Abstract: An ultrasonic system is responsive to the relative position of a movable device within a fluid-filled structure. A transducer transmits ultrasonic signals from a location fixed within the structure to the device for reflection thereby and for picking up the reflected signals.

Abstract: A construction and method of producing an elongated underwater acoustic array includes a plurality of interconnected hydrophones and circuit modules protected by a plastic foam cushioning sheath, covered with a tough, essentially acoustically transparent hose-like jacket and containing a plurality of aramid fiber ropes as strength members to carry the tensile loads on the array. An elongated tube-like fabric retaining member is interposed between the sheath and the exterior hose jacket which is longitudinally stitched to provide a plurality of spaced parallel tubes, each of which is of just sufficient diameter to contain one of said strength members. The strength members are terminated at a connector at each end of the array, and a spacer member is placed near each connector to spread the strength member ropes to the desired diameter. The spacer members and the adjacent ends of the retaining members are each cemented to the strength member ropes.

Abstract: A subsea acoustic relocation system provides an apparatus that includes in one embodiment an anchor, and in another embodiment a weighted frame having in part a casing which has an inner bore with an open top portion. A line canister connected to the anchor or disposed within the casing bore has an opening through which a contained canister line can pay out. The canister line is placed within the line canister and is anchored at one end to the anchor or frame, the other end of the canister line being a free end which dispenses from the canister during operation. An acoustic transponder release assembly is detachably affixed to the anchor or frame (within the casing bore) at a provided removable connection which can be broken by an acoustic signal. The acoustic transponder release assembly has attached to it the free end of the line canister with the acoustic transponder release forming a temporary connection of the free end of the line to the frame.

Abstract: A system and method for determining the position of towed marine object relative to a towing vessel. The system comprises a towing vessel, a slave vessel, and the towed object. An acoustic transceiver is located on either the towing vessel or the slave vessel with an acoustic receiver located on the other vessel. One or more acoustic transponders are associated with the towed object. The distance between the towing vessel and the slave vessel is determined, for example, by radio navigation which is calibrated by a high precision range-range system. The acoustic transmitter emits an interrogation signal which causes the transducer(s) to emit a response acoustic signal which is recorded at the two receivers. Using the time for the response signal to reach each of the receivers and the velocity of sound in water, the distance of the transducer from each vessel is calculated. With the three distances the location of the transducer relative to the towing vessel is determined by trilateration.

Abstract: An improved ultrasonic transducer in which signals from portions of the transducer located a distance apart from each other are compensated for the cancellation affects due to a reflected energy striking one part before the other by use of switching circuits which pass either in-phase or out-of-phase components from the portions of the transducer to a summing circuit in such a manner that the summed output is improved.

Abstract: A low cost, efficient, ultrasonic transducer and method comprises a narrow beam electrostatic transducer and a beam transformer operated in air for expanding the emitted beam of the electrostatic transducer relative to a single axis. The beam transformer is a sonic reflecting surface spaced from the ultrasonic beam generator and within the near field thereof and having a geometric surface in which all points of said surface are generated by the revolution of a line about a fixed axis which is normal to the plane of the electrostatic transducer. A partial surface of a cone, the axis preferably being offset from the axis of the narrow beam electrostatic transducer and placed in the near field thereof transform the narrow beam to a broad beam with the beam transformer being an effective coupling element for the emitted beam and the return echo for ranging systems which are both efficient and easy to produce and do not have significant alignment problems.