Conventional Beamforming Algorithm Based on Polarization Filtering for an Acoustic Vector-Sensor Linear Array Mounted Near a Baffle

Abstract

We investigate the beamforming method for detecting signals and estimating their directions of arrival for an acoustic vector-sensor linear array mounted near a baffle. The array-measurement model is established based on the baffle reflection coefficient, which is calculated using transfer matrices and matched boundary conditions. Herein, we propose a conventional beamforming (CBF) algorithm based on polarization filtering. First, the CBF output is directly decomposed into a sum of polarization monochromatic signals by the quaternion Fourier transform. Next, polarization filtering is conducted on each monochromatic signal and is regarded as a postprocessor to the CBF algorithm. This filtering in the polarization domain can improve the signal-to-noise ratio of the CBF algorithm. The proposed algorithm produces a lower noise level than the CBF algorithm. Moreover, the performance of this algorithm is related to the degree of polarization of the noise, and the best performance is obtained as the degree of polarization approaches zero. In this study, the performance of the proposed algorithm is evaluated by simulations and experiments.