Abstract: A high intensity, low frequency underwater transducer for non-lethal deterrence of terrorist swimmers or divers in a body of water. The invention consists of a motor driven flextensional underwater transducer. In one embodiment, the phase of a transducer is sensed, enabling multiple projectors to achieve high acoustic sound pressure levels by beamforming and/or modal constructive interference (e.g. taking advantage of harbor bottom topography and boundaries.).

Abstract: Each of a pair of electrically conductive spiral coils is ensconced in a disk-shaped matrix. The two coil-ensconced matrices are joined face-to-face so as to sandwich between them a thin, non-magnetic elastic layer. An electronic device is connected so that each coil and a corresponding capacitor form an LC circuit. Electrification of the two LC circuits results in the departing and returning, in oscillatory fashion, of the two coil-ensconced matrices. This resonant behavior is both electromagnetic and mechanical in nature. The intermittent electromagnetic repelling is related to the LC circuitry and the oppositely polar electrifications of the respective coils. The springy mechanical activity is based on a spring-mass model and involves the elasticity of the intermediate material and the entrainment of ambient fluid.

Abstract: A Manually Agitated Underwater Signaling Device used for SCUBA divers, snorkelers and other water-sport enthusiasts. The Manually Agitated Underwater Signaling Device includes a water tight right circular cylindrical body containing one or more rigid spheres inside, an integrated slot for the connection of a lanyard to one end of the right circular cylindrical body and a spherical base integrated into the other end of the right circular cylindrical body. The right circular cylindrical body is comprised of two body halves, a right half and a left half. The right half includes a tongue ridge with an energy director around the perimeter forming a mating surface. The left half includes a recessed groove around its perimeter forming a mating surface that intersects with the right half when aligned together. The Manually Agitated Underwater Signaling Device includes an exterior surface texture to improve the grip.

Abstract: A marine seismic energy source includes a seismic tow cable configured to be towed by a vessel from one end and at least one seismic source coupled proximate another end of the tow cable. The at least one seismic source is associated with a depth controller. The depth controller is configured to move the seismic source to a selectable depth in a body of water.

Abstract: Each of a pair of electrically conductive spiral coils is ensconced in a disk-shaped matrix. The two coil-ensconced matrices are joined face-to-face so as to sandwich between them a thin, non-magnetic elastic layer. An electronic device is connected so that each coil and a corresponding capacitor form an LC circuit. Electrification of the two LC circuits results in the departing and returning, in oscillatory fashion, of the two coil-ensconced matrices. This resonant behavior is both electromagnetic and mechanical in nature. The intermittent electromagnetic repelling is related to the LC circuitry and the oppositely polar electrifications of the respective coils. The springy mechanical activity is based on a spring-mass model and involves the elasticity of the intermediate material and the entrainment of ambient fluid. The dual oscillatory modes are merged at the same frequency through tuning of either/both oscillatory mode(s).

Abstract: Disclosed is a device for producing an intracorporeal pressure pulse comprising a pressure pulse source configured to generate a collimated pressure pulse and an acoustic lens including at least one ring-shaped focusing section configured to focus a pressure pulse generated by the pressure pulse source substantially to the vicinity of the central axis of the ring-shaped focusing section.

Abstract: Reflective apparatus and method by which energy is radiated in divergent fashion from an elongated source and is reflected by a first parabolic reflector as a paraxial beam, focused by a second parabolic reflector onto a hyperbolic reflector and reflectively concentrated by the hyperbolic reflector at a focus at a distance from the source. The system also shields the point from extraneous radiation that would not be concentrated at the point. In one exemplary application, electromagnetic energy radiated from a point or linear source is focused by the multiple reflector system to a very high concentration at a point, for example, within an organism such as a human or animal body.

Abstract: A high-pressure, moving-piston pulse engine (modified HIPPE) 10 is used to produce one or a series of pulses of acoustic energy in a marine environment for acoustic communication, detection, classification or jamming. The HIPPE engine 10 is modified by removing its nozzle and replacing it with a pipe 58 which is fastened to the exit of the combustion chamber 56. A gas disperser 60 is affixed to the engine 10 or pipe 58 so that a portion of the disperser 60 extends inside of the pipe 58 the inner surface of which is spaced from the outer surface of the disperser 60 so that an annular void is formed between the pipe 58 and the disperser, through which void the combustion gases can be vented. The axial course of the gases is changed by disperser 60 to a controlled course with velocity vectors transverse to the pipe axis. The engine 10 is placed in a body of water 14 at depth or near the surface and operated either manually or automatically.

Abstract: An apparatus for generating acoustic waves has an acoustic transducer with a first electrode serving as a membrane and adjoining an acoustic propagation medium and a second electrode spaced from the first, between which an electrolyte is situated. The acoustic transducer is fashioned transparent to X-rays.

Abstract: A boomer for generating acoustic signals in a marine seismic survey has a frame towed by a survey vessel. A coil is mounted to the frame and a conductive plate is adjacent to the coil. A capacitor is mounted to the frame, and control electronics system delivers an electric charge stored in the capacitor to the coil. The invention obviates the need for heavy conductive cables between the survey vessel and the boomer in conventional systems where the capacitors are carried by the vessel, while maintaining the desirable acoustic properties of the boomer.

Abstract: A pressure-pulse therapy apparatus, including a dome-shaped reflector, at least one ring section, a central x-axis, an open end, a flexible diaphragm capping the open end, a fluid medium within the reflector and diaphragm, a pressure-pulse source immersed in the fluid medium and located on the x-axis for generating a primary pressure pulse, and a power supply for the pressure-pulse source. The reflector includes a center section that has a predetermined first curvature and associated reflective characteristics to reflect the primary pressure pulse to form a first subordinate pressure pulse of a compound pressure pulse. The ring section is substantially concentric with the center section and has a predetermined second curvature and associated reflective characteristics to reflect the primary pressure pulse to form at least one additional subordinate pressure pulse of the compound pressure pulse.

Abstract: A circuit for driving an electromagnetic source for generating acoustic waves has a dischargeable high-voltage capacitor with a diode or a diode module connected in parallel therewith.

Abstract: A reusable low frequency projector system that is capable of producing coherent broadband, high power, low frequency acoustic pressure waves underwater. The projector has two halves each with a spiral wound insulated wire core. The spiral wound wires are separately encapsulated and then joined flexibly in a contiguous parallel orientation. When energized by a voltage source the encapsulated spiral wound wires are repelled from one another and then come back together when not energized, imparting a pressure wave to the water at a desired frequency. The projector requires no pressure compensation devices for operation.

Abstract: This invention is a thermoacoustic system for communicating between an airborne or spaceborne vehicle and a sound detector that is located aboard an object beneath the surface of the water. The foregoing system comprises a laser or particle accelerator that is located aboard an airborne or spaceborne vehicle. The laser produces a light beam whose amplitude is subsequently modulated or whose pulses are varied in time. A particle accelerator would produce a pulsed particle beam that varies in time. These modulated or varied pulses are focused or deflected to a small layer of water at the air/water interface so that the beam will be absorbed by the water causing the water to produce an acoustic signal that will propagate to the sound detector.

Abstract: In order to reduce the amount of air trapped in hydraulic assisted steering systems (1), a communication (13, 14) is established between the area of the oil expanding volume (8, 10, 11), which is the top area in the mounted position, and an open system (2), for example a tank volume.

Abstract: The invention disclosed is a drive assembly for acoustic sources having sound emitting surfaces (1) adapted to be excited into vibrational motions. The invention is especially for use in seismic surveys. The drive assembly includes an electric rotational motor with at least one associated axle comprising at least an axle part (18) and a number of rods (21, 22) arranged radially in relation to the axle. The inner ends of the rods (21, 22) are influenced by the axle part (18) and the outer ends of the rods (21, 22) are adapted to excite the sound emitting surfaces (1) into vibrational motion. The inner ends of the rods (21, 22) are connected to the axle part (18) and the connection is adapted to perform both push and pull forces upon the rods. One or more spring elements (23) are provided between at least one of the rods (21, 22) and the sound emitting surfaces (1).

Abstract: An improved manually operated signaling device to produce audible sound underwater. An air tight housing comprising a tubular member with end-caps permanently sealing each of its two ends and having contained within a metal echo-chamber fixed at each end of the housing plus a solid metal piston member. The inside diameter at each end of the housing is step-relieved so as to accept and hold fast the outside diameter and depth of the echo-chambers. The echo-chamber is a cylinder having one end open and one end closed with its closed end inserted into the ends of the housing. The outside diameter of the piston is slightly smaller than the inside diameter of the housing. The piston also has a length greater than its own diameter which allows the piston free movement along the longitudinal axis of the housing. A colored thin walled jacket may optionally cover a part or all of the housing exterior. A ring may be connected to the exterior of one of the housing end-caps for attaching a lanyard.

Abstract: Drive assembly for acoustic sources having sound emitting surfaces adapted to be excited into vibration movements, in particular for use in seismic explorations. The assembly comprises an electric rotational motor (17) with an associated axle which comprises an axle part (18) the outer cross-sectional contour of which at least partially in the axial extension of the axle part is non-circular, but preferably smoothly rounded. Further the assembly comprises a number of push rods (21, 22) being arranged radially in relation to the axle (18) and adapted to preferably indirectly at their radially inner ends (23, 24) to be influenced by the non-circular axle part (18) during rotation of the axle, whereas the radially outer ends of the push rods (21, 22) are adapted to excite said sound emitting surfaces (1) into vibrational movement.

Abstract: The present invention relates to a system for studying, identifying and cacterizing thermal gradients in a volume of water. The system includes a frame for supporting one or more measuring devices and a source of heat for generating a thermal plume in the volume of water. The frame includes a first plate to which the measuring devices are mounted by a plurality of mounting blocks spaced about the periphery of a hole in the first plate. The frame further includes a second plate, spaced from the first plate, to which the source of heat is mounted.

Abstract: A cavitation chamber is driven by a hydraulic driving system in which acoustic pulses are generated by repeated water hammers. In the driving system a liquid is pumped through a conduit. The flow of liquid through the conduit is periodically interrupted by a valve. A water hammer is created each time the valve closes. Acoustic pulses produced by the water hammer propagate directly into a cavitation chamber where they are reflected back and forth by acoustically reflective plates. The cavitation chamber may be applied to degas liquids, mix chemicals or slurries, or promote sono-chemical reactions. The design generates acoustic pulses efficiently. The acoustic pulses are coupled to the cavitation chamber with minimal losses. The apparatus is rugged and inexpensive when compared to systems which incorporate electromechanical transducers.

Abstract: Rarefaction pulses are generated in a chamber containing a liquid to be degassed. The rarefaction pulses are generated by creating repeated water hammers in a conduit. The water hammers result in sudden high pressure pulses which deform a stiff springy, impermeable deflection cap. After the water hammer pulses pass, the deflection cap snaps back toward its equilibrium position. The snapping action of the deflection cap causes a rarefaction pressure pulse which enhances bubble formation in the chamber. The deflection cap may resonate for some time after each water hammer pulse passes. During the interval when the deflection cap resonates the deflection cap generates an attenuated acoustic wave which is transmitted into the liquid being degassed. The deflection cap may also be driven by a system in which a high pressure fluid, such as steam, is introduced into a sealed chamber behind the deflection cap and then suddenly vented.

Abstract: The invention provides apparatus for shaking structures such as fins in a fluid agitator, shaking tables, shaking screens, conveyors, or the walls of bins or hoppers. The apparatus is driven by a hydraulic driving system in which high pressure pulses are generated by repeatedly creating water hammer within a conduit. The high pressure pulses are directed to a chamber where they act against a wall of the chamber to periodically push on the structure. Preferably, the structure is spring-like so that after a high pressure pulse has passed the wall of the chamber is returned to its equilibrium position. In one embodiment of the invention a water hammer pressure pulse is directed into a reinforced hose in contact with a surface to be vibrated. The high pressure pulse causes the hose to expand and move the surface to be vibrated. Water hammer pulses are generated periodically so that the surface is maintained in continuous vibration.

Abstract: A method and apparatus are disclosed for generating intense acoustic pulses by means of the water hammer effect. The method involves generating a water hammer in a conduit by suddenly interrupting a high velocity flow of fluid through the conduit. The kinetic energy of the fluid flowing in the conduit is converted into a high pressure pulse which propagates along the conduit away from the point where the fluid flow was interrupted. The high pressure pulse deforms the wall of the conduit so as to radiate acoustic energy away from the conduit into a fluid medium surrounding the conduit. The relative amount of energy dissipated in the form of mass flow in the surrounding fluid and acoustic energy in the surrounding fluid can be adjusted by changing the characteristics of the conduit wall. The direction in which acoustic energy is radiated into the fluid medium surrounding the conduit can be set by making the conduit wall asymmetrical or by bending the conduit.

Abstract: An acoustic projector wherein a unitary acoustic resonator produces active sonar signals in more than one frequency band. The double-slotted resonator is coupled to a transducer which is capable of exciting the resonator in two, distinct, volumetric modes of vibration using two asymmetric, generally arcuate vibrating members. Transduction techniques can include variable reluctance or piezoceramic transduction. Internal cavity pressure release may be achieved by bladders, compliant tubes, and the like.

Abstract: A method of and an apparatus for the high-resolution sea bottom prospecting, in which an electroacoustic paraboloidal transducer is placed into water, the electrodes of which are near the focus of the paraboloid and are connected both to a capacitor bank the capacitance of which may be varied at will and to a supply circuit for the generation of an electroacoustic discharge between said electrodes. As the capacitance varies the delay time between the primary pulse or underwater prospecting pulse and the cavitation pulse is recorded at any discharge, and at the same time dominant frequency of the prospecting signal spectrum is determined. Afterwards capacitance values are set so as to provide both cavitation pulses the contribution of which to the resulting pulse is minimum and a dominant frequency spectrum as broad as possible.

Abstract: A sonar transmitter includes a source means for providing an actuation signal to drive an electromagnetic transducer projector without the use of bias magnetization. The invention utilizes an offset actuation frequency technique in which electrical driving signals are applied which have a frequency or frequencies other than the desired frequency of the acoustic signal projected into a liquid medium. In presently preferred embodiments, one or two driving signals may be utilized. If one driving signal is utilized, the acoustic signal will be at twice the driving signal frequency. If two driving signals are utilized, the acoustic signal will be at the sum or difference frequency of the driving signal frequency. The actuation signal is applied to coils of the transducer's electromagnets to produce an electromagnetic attractive force having a significant component at the desired frequency of the acoustic signal.

Abstract: A submersible acoustic generator for projection of sound waves into a body f water comprises a tubular resonator, open at its lower end and closed at its upper end, and having a multiple-plate thermoacoustic stack located near the upper end between a pair of heat exchangers which set up a temperature gradient in the stack. The upper heat exchanger is heated by a chemical fuel, and the lower heat exchanger is cooled by the surrounding water. The resonator is gas-filled, and the wavelength of the oscillations produced is approximately twice the length of the resonator. A portion of the resonator tube can be surrounded by a coaxial tube which serves as an impedance matching stub. The stack plates can be made anisotropic by means of embedded copper wires. In alternative versions of the apparatus, the resonator can have two stacks, one near the open end and the other near the closed end, and the temperature gradient in the stack can be established cryogenically.

Abstract: Simulation of ship's noises by means of liquid jets penetrating into the water.

Abstract: An acoustic wave energy generator comprises a body having an internal gas-pressurisable first chamber 1 adjoining a second chamber 2 into which a liquid is introduced to cover a vibratable means 4 which may be a flexible diaphragm and is mounted on the second chamber so as to close an associated opening 5 in the second chamber. After the first chamber 1 is pressurised with a first gas a common closed opening between the chambers is opened to cause communication between the chambers 1,2 to permit a shock wave emanating from the first chamber to impinge on the liquid. As a result, the vibratable means 4 is caused to vibrate so as to produce acoustic wave energy in response to the impingement of the shock wave on the liquid. By using different liquids and/or different heights of liquids in the second chamber the generator may be tuned to provide acoustic wave energy with a relatively narrow chosen frequency range or within a chosen substantially single frequency.

Abstract: Low frequency underwater acoustic radiator apparatus includes an air-trapping chamber with a lower portion open to the water, characterized by a mean density higher than that of water. A closed, rigid float element having a mean density equal to or lower than that of water is disposed with a selected loose fit within the chamber. When the chamber and float combination are submerged in water with a substantially vertical orientation of the chamber, the float element floats within the chamber, with the trapped air functioning as a spring coupling. A vibromotive element is coupled to the float element or the chamber element to induce oscillation of the coupled element. The coupling of the chamber and the float by the air spring converts the dipole oscillation of the oscillating element into a monopole pulsation suitable for a low frequency underwater sound radiator.

Abstract: An electrically driveable shockwave source for generating acoustic shockwaves of the type suitable for medical therapy, as a coil arrangement and a membrane disposed adjacent the coil arrangement. The membrane and/or the coil arrangement is formed by a multi-layer structure, with each layer having electrically conductive elements therein insulated from each other, in the form of electrically conductive sections in the membrane, or electrically conductive windings connected in parallel in the coil arrangement.

Abstract: This invention relates to a sound wave generator with a variable effective aperture angle according to the electromagnetic principle for therapeutic applications and particularly for the contactless smashing of a concrement situated in the body of a living being. The sound wave generator includes a flat coil and a metallic diaphragm which is insulated with respect to the flat coil. The flat coil includes three separately activatable and concentrically arranged coil sections. The sum of the areas of the inner coil section and the center coil section is equal to the sum of the areas of the central coil section and the outer coil section. By means of the varying activation of the coil sections, the aperture of the shock wave source can be changed so that the focus geometry and the peak pressures can be varied for different applications, particularly kidney and gallbladder lithotrity.

Abstract: A signaling apparatus for generating an audible sound includes a housing containing a cylindrical chamber having two ends, an end member secured over each end, and a projectile member contained within the cylindrical chamber. The projectile member preferably has an outer diameter slightly smaller than the inner diameter of the cylindrical chamber, for limiting lateral movement of the projectile member. The end members form a water-tight seal with the housing to keep moisture out of the cylindrical chamber. The projectile member is preferably a metal ball. The end members have outer surfaces and optionally include a loop attached to the outer surface of one of the end members for receiving a cord. The housing, including the end members, is preferably made of PVC, brightly colored and fluorescent so that the apparatus can be more readily seen in murky water. A foam sleeve is preferably provided over the housing for improving the grip of a person holding the device.

Abstract: Disclosed is a sound source which will broadcast predetermined frequency ustical energy throughout subaqueous environmental mediums. It includes a housing body of cylindrical configuration with elongated slots located at uniform distances around the periphery thereof. A flexible, resilient sleeve surrounds said housing in such manner that it forms a movable diaphragm over each of said slots. By means of a pressure control system, internal gas pressure within said housing body may be regulated to make it less than the pressure of the subaqueous medium external thereto, thereby pulling said diaphragm inwardly through said slots. A plurality of motor driven rollers roll around the inside surface of said housing and contact the inside surface of said flexible sleeve, thereby pushing it in an outwardly direction back through said slots, so as to displace some of the subaqueous medium adjacent thereto.

Abstract: Disclosed is an acoustical energy generator having a venturi front section o which is attached a pair of rear tail pipes. A pair of return flow manifolds are respectively connected between said rear tail pipes and said front venturi section at such locations that the static pressure in the former are greater than the static pressure in either of the latter when a fluid is flowing therethrough. Controllable valves are optionally disposed in said return flow manifolds to regulate the fluid flow therethrough, and a freely rotatable flutter valve may be disposed at the common junction of said venturi section and tail pipes to facilitate the rapid transfer and/or cutoff of flow from the former to both of the latter in an alternating manner, and thereby effect a more positive generation of cavitation at a desired frequency of operation. A bridle is connected to the front end of the venturi section and a tractor vehicle is attached thereto by means of a tow cable.

Abstract: An underwater acoustic generator comprising a tapered solid positioned in a luid flow to produce a cavitation void. A source of gas supplies the void with gas to produce a resonant gas bubble.

Abstract: An underwater transient sound generator for broadcasting optimum acoustical onic energy in sea water with an appropriate intensity and frequency spectrum to achieve passivation of acoustical mines. A high pressure bubble is released from a chamber while a resilient diaphragm is simultaneously vibrated, the diaphragm having at least one of its surfaces in contact with the sea water. The system provides an improved pneumatic-mechanical impact sound source that produces a controllable distribution of high power, broad band spectrum acoustical energy, to temporarily inactivate acoustical mines, while masking the noise of the ship as it passes the mine.

Abstract: A sonic generator comprises a resonant bar, a housing and magnetic excitation units connected between the resonant bar and the housing. The magnetic excitation units are connected to the bar using a mounting connection which is a sleeve having an inside diameter slightly greater than the outside diameter of the bar. A resilient elastomer such as urethane is mounted between the sleeve and the resonant member.

Abstract: A system for sweeping acoustic and magnetic mines or a combination of both s disclosed as comprising a pair of spatially disposed magnetic pipes that are held in their respective spatial dispositions by front and rear straps, and an acoustical energy generating pipe suspended between said front and rear straps by hinges in such manner that it is also disposed between said pair of spatially disposed magnetic pipes. A tractor vehicle moves all of the aforesaid pipes and their associated elements as a unit along a course intended to be cleared of acoustic and/or magnetic mines.

Abstract: A seismic source marine vibrator having compound hydraulic cylinders for high and low frequencies is used to generate both low frequency and high frequency acoustic pulses. Low frequency pulses are generated by operating a low frequency radiating surface and a high frequency radiating surface simultaneously. High frequency pulses are generated by operating the high frequency radiating surface alone.

Abstract: A shock wave generator for an apparatus for non-contacting disintegration of calculi in the body of a life form has a membrane of electrically conductive material which terminates a volume filled with a shock wave conducting medium, and a coil having windings disposed adjacent the membrane. The coil is connectable to a high voltage source with two terminals. For maintaining a long useful life of the membrane without significantly reducing the efficiency of converting electrical energy into shock wave energy, the membrane is provided with a potential such that a positive difference in potential is present between one terminal of the coil and the membrane, and a negative difference in potential is present between the other terminal of the coil and the membrane.

Abstract: A novel device and method are provided herein for the production of underwater sound. This device, termed a plasma jet underwater acoustic source includes a central electrode and a concentric insulator having a longitudinal bore to accommodate the central electrode, the bore being spaced from the central electrode by a longitudinally-extending annular chamber. A plasma cavity is bounded at its upper end by the central electrode, and is in communication with the annular chamber. The cavity is adapted to be connected to a gas supply, so that it may be filled with gas. An outer housing of electrically-conductive material surrounds the insulator and terminates in a centrally-apertured end plate whose central aperture provides an extension to the plasma cavity, the end plate being adapted to be grounded.

Abstract: An electromagnetically driven vibratile piston underwater transducer element generates acoustic intensity levels in excess of 25 peak Watts per square inch of radiating surface in the low audible frequency region within the approximate range 500 to 2500 Hz. The design achieves an efficiency greater than 50% and a very low Q of less than 2. The electromagnetic design employs two separate independent air gaps and a unique mechanical coupling system that combines the electromechanical forces generated in each gap in the proper phase and transmits the combined oscillatory force to drive the vibratile piston.

Abstract: The power handling capacity of a high-power low-frequency underwater transducer including an inertial mass-loaded vibratile piston assembly is greatly increased by increasing the heat conduction from the inertial mass member by designing the vibrating structure to place a surface area portion of the inertial mass member in direct thermal contact with the water environment in which the transducer is submerged. In order to reduce the sound radiation from the exposed surface of the submerged inertial mass member and to obtain a broadband response with a Q equal to 1 or less, a novel rigid hollowed piston construction is described which greatly reduces the weight-to-stiffness ratio of the vibratile plate and achieves the desired low Q as well as a reduction of sound radiation from the exposed inertial mass surface by at least 20 dB below the radiation from the surface of the vibratile plate member.

Abstract: An electromagnetically driven vibratile piston underwater transducer element generates acoustic intensity levels in the order of 50 peak Watts per square inch of radiating surface in the low audible frequency region in the vicinity of 1 kHz. The design achieves an efficiency greater than 50% and a very low Q of less than 2. The air gap is designed to seat mechanically if the unit is operated accidentally at high-power levels while acoustically unloaded thereby protecting the spring assembly from unsafe amplitudes of vibration. The mechanical protective design also serves to protect the transducer vibrating structure from failure if the transducer is exposed to the proximity of an underwater explosive shock wave. The transducer construction results in a minimum overall length so that when the transducer element is mounted in a planar array attached to the hull of a vessel the projection of the radiating surface of the array from the surface of the hull is minimized.

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 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: A seismic method and apparatus utilizes two point sound sources located at the same location on the earth to produce sound waves at different amplitudes and times. The reflections of the sound waves are analyzed to determine the acoustic properties and rock boundaries within the earth.

Abstract: A sleeve shuttle air gun is described which can be fired by a solenoid valve without dumping compressed air into the ambient prior to firing, thereby avoiding the generation of premature impulses caused by such dumping and avoiding the heavy duty complex solenoid dump valves and two-stage dump valves of the prior art. The sleeve shuttle is automatically returned to its initial closed and sealed position after each firing of the airgun by the refilling flow of only one level of pressurized air without a separate low level pressure source to control the sleeve shuttle. A long acceleration path is provided so the sleeve shuttle attains velocity prior to opening the discharge ports for producing a sudden, powerful discharge. The end of the sleeve shuttle travels completely beyond the discharge ports, and is then damped by interaction with damper ports located beyond the discharge ports.

Abstract: A high power sonar pulse generator driven by a low power electrical motor erein a flywheel, placed in the mechanical system, connects the small motor and large generator. Since the large power output from the pulse generator is required only intermittently, the energy stored in the rotating flywheel allows a small motor to effectively drive the large output pulse generator while a braking effect on the flywheel is used to vary the sonar impulse producing an advantageous FM glide.