Abstract: A seismic vibrator system for imparting compressional and shear wave vibrations into the earth has an earth contacting base with a vertical post. A tubular hub is slidably received on the post in a piston/cylinder relationship. Spaced apart horizontal top and bottom plates are secured to the hub. A mass is slidably supported between the plates. Pistons interconnect the hub and the mass. Hydraulic energy is used to reciprocate the mass vertically on the post and horizontally between the plates.

Abstract: A high-volume source for very low frequency applications in which conventional speakers are inadequate is disclosed. A presently preferred embodiment comprises a reservoir 32 with a pressure relief 33; a controller 34; a supply blower 36; an exhaust blower 38; a positive plenum 40; a negative plenum 42; an orifice plate with valving 44; a horn 46; and pressure transducers 48, 50, 52, 54, feeding detected pressure levels to the controller 34. An electrical command signal s(t) is also input to the controller. The command signal is a voltage analogous to the acoustic pressure or volume velocity to be output by the source.

Abstract: A mine sweeping method and related apparatus for achieving at least tempoy passivation of underwater acoustic influence mines, by the generation of particular underwater sounds of progressively increasing intensity. The water is by repetitively injecting into the water individual metered slugs of heated water, which water is heated to its saturation pressure but below the critical point. The metered slugs of heated water may be of the same or of progressively increasing size, i.e. weight, and can be released from a heated pressure chamber into the water from either a stationary array or from an array towed from a moving ship, and at a depth such tht the expanding bubbles, produced by the change of state of the heated water, do not break the water surface. The rapid expansion of the metered slugs produce the desired sound output for temporarily rendering the acoustic influence mines passive by actuating their anticountermine circuits.

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.