Fully Steerable and Interference Suppressible Differential Beamforming for Linear Acoustic Vector Sensor Array With Small Aperture

Differential line arrays (DLAs) hold significant potential for practical signal enhancement, but DLAs are not capable of realizing the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i>th-order fully steerable function. To overcome this problem, this paper introduces a novel fully steerable differential beampattern with controllable nulls to address the limited steering capability of conventional differential beamformers based on linear arrays, which enables asymmetric beampattern design. The proposed differential beamformer is implemented through McLaughlin series expansion to approximate the constructed target beampattern and establishes the relationship between controllable nulls and the weights of beamformer, thereby enforcing the null constraint. The main contributions of this paper are as follows: 1) A fully steerable differential beamforming design method is proposed, which not only achieves the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i>th-order fully steerable function but also enables more controllable interference suppression; 2) Validated through simulation comparisons, the proposed method based on linear acoustic vector sensor arrays (LAVSAs) mitigates the limitation of conventional linear arrays, which fail to achieve the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i>th-order fully steerable function, and exhibits superior directivity factor performance. Finally, the effectiveness of the proposed method is demonstrated by experimental results.