Adaptive Beamformer Using Predetermined Shading Windows
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Solution Overview
Problem
Conventional sonar systems face challenges in efficiently processing sonar returns in dynamic underwater environments due to interference from unwanted acoustic returns, which can lead to reduced performance and sensitivity, particularly in shallow water conditions.
Innovation Solution
The implementation of adaptive beamforming techniques using a transducer array with multiple elements arranged in a grid, applying predetermined shading windows to minimize interference and maintain distortionless response, combined with interferometric methods to determine angles of sonar returns, allowing for improved image formation of underwater environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional adaptive beamforming algorithms (e.g., MVDR) are used to reduce interference, then interference reduction is improved, but computational complexity increases significantly
Solution Approach 1:
The patent changes the parameters of the beamforming algorithm by using predetermined shading windows with fixed mathematical formulations instead of dynamically calculating optimal weights through covariance matrix inversion. This reduces computational complexity while maintaining interference reduction capabilities through predefined window functions that adjust signal weights based on spatial position.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing shading window functions before sonar operation. These predetermined windows are prepared in advance based on expected spatial distributions of useful and interfering signals, eliminating the need for real-time complex calculations during actual sonar beamforming operations.
2Object-affected harmful factors
If traditional adaptive beamforming algorithms are used to reduce interference, then interference reduction is improved, but desired signal cancellation occurs
Solution Approach 1:
The patent applies local quality by designing shading windows that provide different weightings to different spatial regions. The predetermined windows are configured to reduce interference from specific directions while maintaining unity gain or appropriate weighting in directions where useful signals are expected, thus avoiding cancellation of desired signals while still reducing interference locally.
Solution Approach 2:
The patent incorporates feedback mechanisms where the sonar system uses information about the spatial distribution of useful signals and interfering signals to select or adjust appropriate shading windows. This feedback allows the system to adaptively choose windows that protect desired signals while suppressing interference, preventing unwanted signal cancellation.
3Measurement precision
If beamforming is used to process sonar returns, then imaging capability is improved, but processing time increases
Solution Approach 1:
The patent changes processing parameters by using predetermined shading windows with closed-form mathematical solutions instead of iterative optimization algorithms. This allows faster computation of beamformed signals while maintaining imaging precision, as the predefined windows can be applied directly without requiring complex real-time calculations.
Solution Approach 2:
The patent reduces processing time through preliminary action by pre-computing shading window functions offline and storing them for rapid application during sonar operations. This preparation in advance eliminates the need for time-consuming real-time calculations, enabling fast beamforming processing while maintaining high imaging capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the clarity and accuracy of sonar images by reducing interference and maintaining sensitivity, enabling better detection and imaging of underwater objects and topography, even in complex acoustic environments.
Implementation Method 1
Sonar transducer elements, or simply transducers, may convert electrical energy into sound or vibrations at a particular frequency. A sonar sound beam is transmitted into and through the water and is reflected from objects it encounters. The transducer may receive the reflected sound (the 'sonar returns') and convert the sound energy into electrical energy.
Implementation Method 2
During beamforming, the sonar system attempts to process returns from a desired direction (e.g., a primary direction of the beam); however, reflections and other acoustic returns may be received by the transducer elements from other directions. These unwanted returns, or 'interferers', may negatively impact the performance and sensitivity of the transducer array.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Provided are method, system, and computer program product for imaging an underwater environment. The method may include receiving sonar returns and converting the sound energy of the sonar returns into sonar return data, and generating first beam data associated with a first beam having at least one first main lobe oriented in a first direction. Generating the first beam data may include: forming the sonar return data in the first direction; applying a first predetermined window to the sonar return data to define a first weighted return data; applying a second predetermined window to the sonar return data to define a second weighted return data; comparing a first power of the first weighted return data to a second power of the second weighted return data; and defining, when the first power is less than the second power, the first beam data based upon the first weighted return data.