For multibeam sonar for the measurement of submarine topography/exploration for objects deposited on the sea bottom, a device which is mounted on a survey vessel or underwater vehiclee, the improvement of the angular and distance resolutions is required to observe the shape of an object to be measured with high definition. In order to improve the angular resolution, generally the array aperture must be made larger, but this is difficult especially for small unmanned underwater vehicles where strict dimension/mass restrictions are placed on on-board devices. As one measure to improve the angular resolution by signal processing, the null steering method, which has a high angular resolution, may be adopted. This method, however, requires procedures such as averaging of the measurement signal with the time window. Therefore, the angular resolution and the distance resolution play off against each other and it is difficult to make them compatible. In this study, the time window width required for the null steering method is substantially reduced, and signal processing technology enabling compatibility between the angular resolution and the distance resolution without upsizing the array was developed. Using actual measured data, the effectiveness of the proposed method was verified.
(This article is written in Japanese and only the abstract is written in English.)
