Active sonar range-dimensional beamforming

To improve the range resolution and suppress range-dimensional interferences, we proposed a new beamformer for active sonar signal processing, which is termed as the range-dimensional beamformer. The proposed beamformer extracts several sub-band components from single echo of the active sonar. Due to the frequency gaps between these sub-band components, their phase shifts form a complex geometric series, which is similar to the array manifold vector of a uniform linear array. Accordingly, borrowing from the traditional angle-dimensional beamformer, we propose the range-dimensional beamformer which can form a beampattern in the range dimension. The corresponding sample covariance matrix is constructed directly from the sub-band components; and the scanning vector is calculated according to their phase shifts at the center frequencies. We give both the expressions and processing procedures of the rangedimensional conventional beamformer and the range-dimensional adaptive beamformer. Furthermore, we give analyses on the processing performance of the range-dimensional beamformer. Numerical simulations and a tank experiment demonstrate the effectiveness of the proposed range-dimensional beamformer.