流速計測のための音響トモグラフィシステムの設計と沿岸海洋への応用

概要

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An acoustic tomography system has been designed with an aim to long-term velocity measurement in coastal oceans. In this system, Travel times of sound waves propagating reciprocally between two acoustic stations are measured accurately by using IkHz pulse signals from GPS(global positioning system). The S/N ratio of signals received is remarkably increased by use of the M sequence(maximum period sequence) and arrayed hydrophones. Beamforming also makes it possible to determine the incident angle of signals reaching the arrayed hydrophones. This system was successfully applied to a 10-km scale velocity measurement in the Seto Inland Sea, Japan. Path-averaged velocities estimated from the reciprocal transmission data were in satisfactory agreement with the result of the ADCP(acoustic Doppler current profiler) measurement which had been carried out at the same site for cross comparison. This study provides us a promising step to the full-scale coastal tomography experiment, performed by a number of acoustic stations which surround the coastal regions such as bays and straits.
社団法人日本音響学会の論文