Orthogonal Linear Array based Product Beamforming for Real Time Underwater 3D Acoustical Imaging

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Main Authors: Menakath, Mimisha M, Panicker, Mahesh Raveendranatha, G, Hareesh
Format: Preprint
Published: 2024
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author Menakath, Mimisha M
Panicker, Mahesh Raveendranatha
G, Hareesh
author_facet Menakath, Mimisha M
Panicker, Mahesh Raveendranatha
G, Hareesh
contents Ocean exploration using acoustical 3D imaging is gaining popularity as it provides information about the 3D geometry of the targets even under mild turbid conditions. A major challenge in underwater 3D imaging is the high cost of the planar arrays and the computational complexity of the image reconstruction algorithms. In this work, we introduce two novel aspects, an L shaped array and a quadrant based time domain receive beamforming with a focus on achieving relatively low computational complexity for real-time 3D imaging in underwater environments. An orthogonal combination of two linear arrays to form an L shape is used to perform two independent and parallel 2D delay and sum beamforming and the 3D image of the target is reconstructed using the product of the resulting beams. In the proposed quadrant-based beamforming, each quadrant in the imaging slice is reconstructed in parallel using the orthogonal L-shaped linear arrays which reside at the edges of the planar array for the quadrant to be reconstructed. The proposed L-array solves the multiple-target ambiguity issue of the cross-array and an L-array placed at the center of the uniform planar array. The proposed method has reduced the main lobe width by 1 degree with 11.8 dB increase in the peak side lobe level when compared to the conventional delay and sum beamforming using a uniform planar array. Although there is an increase in the side lobe level, the asymmetric beam pattern of the proposed L array and the quadrant-based beamforming restrict the side lobes within a quadrant. The proposed method achieves a reduction in computation time by a factor of 97 for 3D imaging compared to the conventional method, while maintaining acceptable image quality. For qualitative analysis, the 3D images of different underwater targets have been reconstructed and compared in simulation and experiment.
format Preprint
id arxiv_https___arxiv_org_abs_2411_09197
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Orthogonal Linear Array based Product Beamforming for Real Time Underwater 3D Acoustical Imaging
Menakath, Mimisha M
Panicker, Mahesh Raveendranatha
G, Hareesh
Signal Processing
Ocean exploration using acoustical 3D imaging is gaining popularity as it provides information about the 3D geometry of the targets even under mild turbid conditions. A major challenge in underwater 3D imaging is the high cost of the planar arrays and the computational complexity of the image reconstruction algorithms. In this work, we introduce two novel aspects, an L shaped array and a quadrant based time domain receive beamforming with a focus on achieving relatively low computational complexity for real-time 3D imaging in underwater environments. An orthogonal combination of two linear arrays to form an L shape is used to perform two independent and parallel 2D delay and sum beamforming and the 3D image of the target is reconstructed using the product of the resulting beams. In the proposed quadrant-based beamforming, each quadrant in the imaging slice is reconstructed in parallel using the orthogonal L-shaped linear arrays which reside at the edges of the planar array for the quadrant to be reconstructed. The proposed L-array solves the multiple-target ambiguity issue of the cross-array and an L-array placed at the center of the uniform planar array. The proposed method has reduced the main lobe width by 1 degree with 11.8 dB increase in the peak side lobe level when compared to the conventional delay and sum beamforming using a uniform planar array. Although there is an increase in the side lobe level, the asymmetric beam pattern of the proposed L array and the quadrant-based beamforming restrict the side lobes within a quadrant. The proposed method achieves a reduction in computation time by a factor of 97 for 3D imaging compared to the conventional method, while maintaining acceptable image quality. For qualitative analysis, the 3D images of different underwater targets have been reconstructed and compared in simulation and experiment.
title Orthogonal Linear Array based Product Beamforming for Real Time Underwater 3D Acoustical Imaging
topic Signal Processing
url https://arxiv.org/abs/2411.09197