Abstract: In marine seismic exploration, it is common for a vessel to tow a streamer, which includes a plurality of pressure sensitive detectors or hydrophones, for the purpose of acquiring seismic signals representative of the underlying structure of the earth. To aid in the interpretation of these seismic signals, it is necessary to know the precise location of the streamer at the time the signals are acquired. Disclosed herein is a method and system for providing a model representative of the location of the streamer relative to the location of the vessel. In one aspect, the system includes an apparatus mounted at the stern of the vessel and coupled to the near end of the streamer. This apparatus is adapted to provide measurements of the yaw and pitch of that portion of the streamer adjacent the vessel. These measurements are employed in the generation of the position model.

Abstract: Disclosed is an improved air gun construction which lends itself to use with a plurality or array of similarly improved air guns which enables easy synchronization and timing of such array of air guns relative to one another. The synchronization and timing is achieved by controlling and monitoring the movement of the shuttle in the air gun. Various sensors are used such as an electrical coil having a constant current flowing therein which produces a flux pattern which is modified when the shuttle is accelerated, thereby inducing a voltage in said coil which is processed by appropriate processing circuitry. Another embodiment employs a magnetic sensor which includes a permanent magnet and coil wrapped therearound; the permanent magnet produces a flux pattern which is altered when the shuttle is accelerated and comes into proximity to the sensing end of said permanent magnet, thereby inducing a voltage in the coil which is then processed in appropriate processing circuitry.