Abstract: A method for operating an impulsive type seismic energy source in a firing sequence having at least two actuations for each seismic impulse to be generated by the source. The actuations have a time delay between them related to a selected energy frequency peak of the source output. One example of the method is used for generating seismic signals in a wellbore and includes discharging electric current through a spark gap disposed in the wellbore in at least one firing sequence. The sequence includes at least two actuations of the spark gap separated by an amount of time selected to cause acoustic energy resulting from the actuations to have peak amplitude at a selected frequency.

Abstract: A wellbore seismic source includes a sparker electrically coupled to a power source. The sparker is disposed in a pressure-sealed canister, wherein the canister is at least partially filled with liquid. At least one of the pressure of the liquid and the energy discharged by the power source through the sparker is selected to cause emission of acoustic energy at a selected frequency.

Abstract: A wellbore seismic source includes a sparker electrically coupled to a power source. The sparker is disposed in a pressure-sealed canister, wherein the canister is at least partially filled with liquid. At least one of the pressure of the liquid and the energy discharged by the power source through the sparker is selected to cause emission of acoustic energy at a selected frequency.

Abstract: A method for operating an impulsive type seismic energy source in a firing sequence having at least two actuations for each seismic impulse to be generated by the source. The actuations have a time delay between them related to a selected energy frequency peak of the source output. One example of the method is used for generating seismic signals in a wellbore and includes discharging electric current through a spark gap disposed in the wellbore in at least one firing sequence. The sequence includes at least two actuations of the spark gap separated by an amount of time selected to cause acoustic energy resulting from the actuations to have peak amplitude at a selected frequency.

Abstract: A system is described for rapidly and accurately determining the topography of land masses as well as individual x,y,z coordinates of discrete targets. The system incorporates a laser altimeter, a laser scanning/steering system with sensor for receiving reflected laser beams, a global positioning system or other non-ground-based reference means, a video camera, computers, and processing software. The system, mounted to an aircraft, selectively scans or steers a pulsed laser altimeter over a swath or point on earth. A Global Positioning System (GPS) or other non-ground-based reference means records the aircraft's position, altitude, and time of position. Concurrently, a computer system records and time tags the laser's range, scanner angles, and airborne platform's roll, pitch, and heading. The processing software correlates all events and measurements using time to determine precise x,y,z coordinates of the ground/targets.

Abstract: Variable focus in a sonar system of the time delay beamformer type using a onvexly curved electroacoustic array is achieved by changing the operating frequency.

Abstract: A cylindrical array radiator that reduces the intensity of energy radiated n undesirable directions. The radiator is constructed so that vertical staves placed on the face of a cylinder are staggered in the vertical direction by a predetermined distance to cancel energy in the undesirable directions.