Abstract: An underwater sound generator comprising dual opposed pistons in a housing. Dynamic seal assemblies of flexible waterproof material are compressed against the peripheries of the pistons and the housing and form a watertight seal that allows axial motion. Controllers regulate the delivery of pressurized hydraulic fluid to hydraulic actuators which drive the axial motion of the pistons according to a predetermined variation.

Abstract: The disclosed device is a marine seismic source which produces a varying FM signal in the low end of the acoustic spectrum. The seismic source uses stiff oscillating radiators to create a signal in the water. These radiators are attached to devices acting as springs with a variable spring rate. Variation of the spring rate as a function of the frequency permits the device to be tuned for maximum power output.

Abstract: The invention relates to a marine seismic source which emits an FM signal linearly increasing from 10 Hz to about 100 Hz. The source has a number of transducers which are flexible sleeves containing a pulsing hydraulic fluid.

Abstract: A hydraulic drive system for an underwater vibrator has a hydraulically driven mass for generating a seismic wave into the seabed. The hydraulic drive system for the vibrator is accomplished by filtering sea water, conveying the filtered sea water to the hydraulic pump where the sea water under pressure is supplied through a control valve to the hydraulic vibrator. The output from the control valve is coupled to the sea water. The hydraulic system provides hydraulic fluid which will not need to be cooled, thereby eliminating the normal cooling system along with several necessary accumulators and sump which are used in a closed hydraulic system.

Abstract: A method and apparatus for seismic prospecting which utilizes two transducer plates that are spaced apart, with two sets of bellows placed in between and sealingly attached thereto, to transmit electrically controlled hydraulic pressure signals onto the two plates. When pressure is applied within one set of bellows, the two plates are pushed apart. When pressure is applied within the second set of bellows, the two plates are pulled together. To accomplish this pulling action of the second set of bellows, two closure plates placed between the two transducer plates are used, one attached to one transducer plate and one attached to the other transducer plate. The first closure plate is attached to the first transducer plate in such a manner that it lies between the second transducer plate and the second closure plate. By applying pressure to the second set of bellows that push apart these two closure plates, the two transducer plates are pulled towards each other.

Abstract: An underwater transducer which includes a fluid circuit having a valve disposed in a plenum chamber having a small aperture open to the ambient water pressure. Fluid flow into and out of the chamber by way of the valve is governed by controlling the valve opening and closing in accordance with movement of an electrodynamic driver which receives an input signal to be transmitted.