Abstract: A very low frequency marine seismic source has a reservoir of water (47) feeding water to an aperture communicating with the surrounding water (13). The rate of water flow through the aperture is controlled by a rotor disc (11) and stator disc (9) having holes which overlap to a greater or lesser extent as the rotor rotates. The modulation of the flow of water produces a modulated pressure signal which is radiated into the surrounding water. The device is intended to produce acoustic signals over a band extending down to 0.5 Hz or lower.

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 generator, or "pulser," and methods for operation are described. The pulser is constructed of a stator and rotor mounted within a housing, each being configured with a central hub and one or more radially extending lobes. An equal number of ports are spaced between the lobes. The lobes of the rotor are cross-sectionally tapered in the streamwise direction. The rotor and stator are maintained within the housing in a coaxial spaced relation from each other. The axial distance between the rotor and stator may be selectively varied by a linear actuator. In a preferred embodiment, the linear actuator comprises a conventional solenoid assembly which is operably associated with the rotor to move it axially within the housing with respect to the stator between a first position, wherein the distance between the rotor and stator is reduced, and a second position, wherein the distance between the rotor and stator is increased. The linear actuator is energized in response to signals from an encoder.

Abstract: In a Measurement-While-Drilling system, selecting the fixed frequency in a pulse signal generator utilizes constructive interference to enhance the signal level in an amplitude modulated signal. The pulse generation system preferably includes a plurality of mud sirens in tandem to further enhance signal level and to provide multiple amplitude levels to increase data transmission rate.

Abstract: A resonant tube having an inlet fitting at one end for connection to the regulator hose attached to an intermediate pressure port on the first stage of a scuba diver's regulator and containing therein a sound generator responsive to pressurized air for generating an audible sound to be propagated against the wall of such tube. The outlet from such tube includes a normally closed air valve which may be selectively depressed to release air from such resonator tube causing incoming air to flow through such generator to generate such audible sound. Frequencies generated are propagated to the surrounding water or air.

Abstract: An elevator cab having a drop ceiling suspended from the cab canopy. The drop ceiling includes a skeleton frame and a plurality of metallic pan members carried by the frame. Each pan member includes a sheet metal member having a lower decorative side viewable from inside the cab, and an upper side having reinforcing and stiffening brackets to which one or more down lights are attached and centered over openings in the sheet metal member. The upper side also carries slidable clip members along the edges of the sheet metal member, with the clip members, when actuated from a retracted to an extended position, securing the pan member to the frame by sandwiching a frame element between the lower sheet metal member and the upper clip members. The sheet metal members of the pan members butt tightly together to conceal intermediate angle members of the frame, and the outer edges of the pan members conceal perimetrically arranged angle members of the frame.

Abstract: An expendable sound source provides a cost effective projection of acoustic nergies in the ocean. A tubular housing contains a d.c. motor that locates its shaft coaxial with the housing. Cylindrically-shaped camming blocks engage spurs in a pair of rigid pistons at both ends of the tubular housing to reciprocate them in accordance with the pattern of the camming surfaces and the motor speed. A flywheel on the shafts and journaling supports assure the projection of arbitrary waveforms and a key-and-keyway cooperation between the housing and prevents the pistons turning in the housings. A self-contained, high energy battery pack is actuated by magnetic reed switch to assure reliable long term projection after deployment. Pressure compensation can be included.

Abstract: A mechanoacoustic transducer is described which comprises a plurality of circumferentially spaced contiguous vibratile plate members which are driven in phase by a rotating cylindrical cam. The cam is shaped to provide radial oscillatory displacements of the vibratile plates of sufficient amplitude to generate acoustic power density levels in liquids in the order of 100 kW or more per square foot of radiating surface of the cylindrical transducer. The transducer has a diameter of several inches, and it can be lowered into a flooded hole of such size as is usually drilled in an oil field. The mechanically-driven transducer provides an economical means for transmitting very intense low-frequency acoustic power into an oil-bearing shale or sandstone deposit for the purpose of dislodging the trapped oil and increasing the flow rate out of the sediment within which the oil is entrapped.

Abstract: A water speed sensor suspended from a fishing boat at the depth fishing gear is being trolled actuates an underwater transducer to transmit a sonic signal detected by an underwater transducer mounted on the boat. The output of the transmitter transducer is fed to an averaging detector circuit which triggers a display of the average speed over a predetermined period of the speed sensed by the speed sensor relative to surrounding water at the trolling depth.