무향수조내에서 수동형 배열센서를 이용한 근접장 소음원 탐지

Abstract

Unmanned underwater vehicles (UUVs) are generally used for various underwater missions, such as survey of the ocean. During UUVs’ mission sound waves play an important role because acoustic communication and positioning systems are used for the control of the UUVs. However, they not only have numerous mechanical components but also use hydraulic and electrical systems, which make loud noise and degrade the performance of acoustic equipment. Therefore, we have to examine the noise characteristics before the use of the acoustic equipment. The investigation method may include localization of the noise sources by using a line array of hydrophones. In order to apply the conventional beamforming algorithm, experiments should be performed in the anechoic environments because it is derived based on the assumption of no reflection. Although KRISO/KORDI has an underwater anechoic basin, it has a free surface that reflects sound waves. Because the acoustic impedance of water is several thousand times bigger than that of air, it is reasonable to assume that it is pressure release condition. In this paper a source localization method in such a kind of environment is studied. The effect of frequency and hydrophone position is analyzed and the results are compared with the experimental ones