다중경로가 존재하는 천해역 환경에서 빔형성기를 이용한 입사각 추정

Abstract

In order to localize the underwater moving vehicles or noise sources multi-channel sensors are used. Generally the localization methods are classified into two ways: one is the time difference method and the other is the beamforming method. Because the time difference method uses trigonometry analysis receiver sensors are widely distributed to minimized localization errors. The other hand the beamforming method uses phase difference which requires sensor distance less than half wavelength. There are various techniques for the beamforming analysis. Conventional method, MVDR(Minimum Variance Distorsionless Response), WGNC(White Gaussian Noise Constraint), and MUSIC(MUlitple SIgnal Classification) are examples. Although they all are applicable to localization of independent noise sources, the performance of MVDR, WGND, and MUSIC is reduced for multiple coherent sources. A shallow water is a mulit-path environments which produce multiple coherent sources because of reflections form sea surface and bottom. This paper estimates incident angles using the measured data in a shallow water using beamforming technology. The results show that the all beamforming techniques well estimate the incident angle which is caused by time-varying characteristics of propagation channels.