Abstract: A marine air gun generates an acoustic signal in water, for example, during a marine seismic survey. The marine air gun includes digital electronic circuitry. The digital electronic circuitry may control an actuator of the marine air gun, digitize and store data from sensors located on or near the marine air gun, send and/or receive digital communications, store and/or output electrical energy, and/or perform other functions. A marine seismic source system that includes multiple air gun clusters may have a separate digital communication link between a command center and each air gun cluster. Each communication link may provide power and digital communication between the command center and one of the air gun clusters.

Abstract: A marine air gun generates an acoustic signal in water, for example, during a marine seismic survey. The marine air gun includes digital electronic circuitry. The digital electronic circuitry may control an actuator of the marine air gun, digitize and store data from sensors located on or near the marine air gun, send and/or receive digital communications, store and/or output electrical energy, and/or perform other functions. A marine seismic source system that includes multiple air gun clusters may have a separate digital communication link between a command center and each air gun cluster. Each communication link may provide power and digital communication between the command center and one of the air gun clusters.

Abstract: A marine air gun generates an acoustic signal in water, for example, during a marine seismic survey. The marine air gun includes digital electronic circuitry. The digital electronic circuitry may control an actuator of the marine air gun, digitize and store data from sensors located on or near the marine air gun, send and/or receive digital communications, store and/or output electrical energy, and/or perform other functions. A marine seismic source system that includes multiple air gun clusters may have a separate digital communication link between a command center and each air gun cluster. Each communication link may provide power and digital communication between the command center and one of the air gun clusters.

Abstract: A marine air gun generates an acoustic signal in water, for example, during a marine seismic survey. The marine air gun includes digital electronic circuitry. The digital electronic circuitry may control an actuator of the marine air gun, digitize and store data from sensors located on or near the marine air gun, send and/or receive digital communications, store and/or output electrical energy, and/or perform other functions. A marine seismic source system that includes multiple air gun clusters may have a separate digital communication link between a command center and each air gun cluster. Each communication link may provide power and digital communication between the command center and one of the air gun clusters.

Abstract: A marine air gun generates an acoustic signal in water, for example, during a marine seismic survey. The marine air gun includes digital electronic circuitry. The digital electronic circuitry may control an actuator of the marine air gun, digitize and store data from sensors located on or near the marine air gun, send and/or receive digital communications, store and/or output electrical energy, and/or perform other functions. A marine seismic source system that includes multiple air gun clusters may have a separate digital communication link between a command center and each air gun cluster. Each communication link may provide power and digital communication between the command center and one of the air gun clusters.

Abstract: A marine air gun generates an acoustic signal in water, for example, during a marine seismic survey. The marine air gun includes digital electronic circuitry. The digital electronic circuitry may control an actuator of the marine air gun, digitize and store data from sensors located on or near the marine air gun, send and/or receive digital communications, store and/or output electrical energy, and/or perform other functions. A marine seismic source system that includes multiple air gun clusters may have a separate digital communication link between a command center and each air gun cluster. Each communication link may provide power and digital communication between the command center and one of the air gun clusters.

Abstract: An apparatus and method for selecting physical cylinders (cylinders accessible for read/write operations) in a disc drive is provided. The disc drive includes at least one rotatable disc. The disc drive also includes a first head, which is positionable adjacent a first disc surface, and a second head, which is positionable adjacent a second disc surface. The first disc surface has a first plurality of greycode tracks and the second disc surface has a second plurality of greycode tracks. Each greycode track of the second plurality of greycode tracks corresponds to a different greycode track of the first plurality of greycode tracks, thereby forming a plurality of greycode cylinders, with each greycode cylinder of the plurality of greycode cylinders including a pair of corresponding greycode tracks. The physical cylinders are a subset (less than all) of the plurality of the greycode cylinders.

Abstract: Apparatus and method for evaluating the presence of a track tear servo defect in a disc drive, characterized as a stepwise radial discontinuity so that the track ends at a different radius than it begins is disclosed for a disc drive. A first defect log is generated for a selected track, the first defect log providing an indication of detected defects for each servo frame associated with the selected track. At such time that a selected servo frame is identified as having a defect, a second defect log is generated for the selected track while the position information provided by the selected servo frame is ignored. The second defect log is then evaluated to determine whether any defects are detected for the remaining servo frames. At such time that a defect appears in the second defect log for a servo frame immediately following the selected servo frame, a track tear condition is declared.

Abstract: Apparatus and method for detecting defective servo frames in a disc drive, the defective servo frames including anomalous position field patterns which generate burst signals of insufficient relative magnitude to facilitate proper servo control. Burst signals are generated from the position field patterns of a selected servo frame and a combination term is determined as a selected combination of the magnitudes of the burst signals. The combination term is compared to a predetermined threshold and the servo frame is identified as being defective when the combination term falls below the predetermined threshold. The combination term is preferably generated from the magnitudes of burst signals generated from three burst patterns: a first burst pattern extending from a first track boundary to a second, adjacent track boundary, a second burst pattern extending from a track centerline to the first track boundary and a third burst pattern extending from the track centerline to the second track boundary.