| 摘要 |
A device in a hydrophone cable which in connection with seismic surveys is towed through the water behind a vessel, the hydrophone cable comprising means for detecting echo signals which are reflected from the sea bed and various layers therebelow. For the purpose of improving the determination of the position of the hydrophone cable which can have a length of approx. 3000 meters, a transmission system is suggested, which comprises transmission elements arranged outside the hydrophone cable itself, the transmission elements serving to determine the position of the hydrophone cable in relation to the elements. In a simple embodiment of the device according to the invention the transmission elements are attached to or are constituted by a separate towing line (4) having a relatively small diameter, the towing line being equipped with stretching means (5) for achieving a relatively straight run. In an alternative embodiment the transmission elements can be implemented as reflectors (9a-9n) for preferably electromagnetic waves, for example in the form of light gas-filled balloons which can be attached to the hydrophone cable via thin, light lines, so that the balloons can be towed at surface positionor fairly high above the water surface. The transmission elements can also be included in a conventional radio and navigation system, possibly together with the system used by the towing vessel for its positioning, in addition to determination of distance and bearing by means of the radar system of the vessel. The transmission elements can also be included as elements in an adaptive control system for combined control of vessel and hydrophone cable. |
