Adaptive Sonar Reception Paths for Noise Suppression
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Solution Overview
Problem
Existing active sonar systems in Doppler mode face challenges in effectively suppressing spatially extended noise sources, such as seabed reverberation, due to limitations in adaptive antenna processing techniques that require prior selection of noise suppression channels and are not suited for short correlation distances.
Innovation Solution
A method for forming adaptive reception channels by creating entangled sub-antennas with shifted phase centers, forming primary and secondary channels, and applying adaptive processing to suppress noise, which involves estimating covariance matrices and determining phase shift vectors to form adaptive secondary reception channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive processing is applied directly on sensor output to maximize degrees of freedom, then noise suppression capability is improved, but covariance matrix estimation time becomes prohibitively long
Solution Approach 1:
The patent divides the full sensor array into multiple sub-antennas, each with fewer sensors. Adaptive processing is then applied separately to each sub-antenna, reducing the dimensionality of covariance matrix estimation from O(N²) to O((N/M)²) where M is the number of sub-antennas. This segmentation enables real-time processing while maintaining effective noise suppression through spatial diversity.
Solution Approach 2:
The patent introduces a new dimension by forming multiple sub-antennas from the same sensor array, creating a hierarchical processing structure. Instead of processing all sensors simultaneously in one dimension, the system processes multiple reduced-dimension sub-antennas in parallel, achieving both speed and effectiveness.
2Loss of time
If sub-antenna grouping is used to reduce processing complexity, then covariance matrix estimation time is reduced, but ability to suppress spatially extended noise sources deteriorates
Solution Approach 1:
The patent combines the outputs of multiple sub-antennas after individual adaptive processing. By merging the processed signals from N sub-antennas, the system reconstructs the full spatial coverage needed to suppress spatially extended noise sources like seabed reverberation, while having benefited from reduced processing complexity at each stage.
Solution Approach 2:
The patent adds a spatial diversity dimension by distributing sub-antennas across different spatial locations. This multi-dimensional approach allows each sub-antenna to capture different spatial characteristics of extended noise sources, enabling effective suppression through combination.
3Adaptability or versatility
If full array beam space adaptive beam forming is used, then degrees of freedom are maximized, but prior selection of reference channels is required
Solution Approach 1:
The patent implements self-service by enabling each sub-antenna to perform autonomous adaptive processing on its own data stream. This distributed self-service approach eliminates the need for centralized reference channel selection, as each sub-antenna independently adapts to local noise characteristics and contributes to overall suppression.
Data Source
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AI summary
The invention relates to a method enabling the formation of adaptive reception paths for a system comprising an antenna consisting of a plurality of sensors. The method according to the invention involves first grouping the sensors according to a given arrangement, so as to constitute N sub-antennas, the phase centers of which are mutually separated by a distance smaller than the correlation length of the received noise or interference. Secondly, the method involves forming, for each sub-antenna, M primary reception paths in given directions. Thirdly and finally, the method involves forming, by adaptive processing, M secondary reception paths. Each of the secondary paths, pointing in a direction m, is formed from the N primary reception paths pointing in the same direction m and formed for each of the N sub-antennas.