Microphone Network Sub-channel Optimization for Signal Isolation
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Solution Overview
Problem
Existing microphone network technologies face challenges in simultaneously determining optimal microphone placement and filter responses to effectively isolate a target signal while minimizing interference from multiple sources, especially in complex environments where interference sources are unknown or numerous.
Innovation Solution
The method involves using a system that assigns multiple sub-channels to possible microphone locations, optimizing both the placement and filter responses simultaneously to minimize interference gain and select a sparse set of active sub-channels, employing multirate filterbanks and convex optimization to process microphone signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple sub-channels are assigned to each possible microphone location, then the ability to isolate target signal and attenuate interference is improved, but the computational complexity and system complexity increase
Solution Approach 1:
The patent divides the frequency spectrum into multiple sub-channels for each microphone location, allowing independent optimization of each sub-channel's filter response. This segmentation enables the system to handle different frequency components separately, improving signal isolation capability while managing complexity through structured decomposition of the overall problem into smaller sub-problems that can be solved independently.
Solution Approach 2:
The patent transforms the discrete sensor selection problem into a continuous optimization problem by relaxing binary variables to continuous values in the range [0,1]. This parameter change enables the use of convex optimization techniques to simultaneously determine microphone placement and filter responses across multiple sub-channels, improving reliability while controlling computational complexity through efficient mathematical programming.
2Reliability
If simultaneous optimization of microphone placement and filter responses is performed, then the overall system performance is improved, but the computational time and complexity increase
Solution Approach 1:
The patent merges the previously separate problems of microphone placement optimization and filter response optimization into a single unified simultaneous optimization framework. By combining these decisions into one integrated problem that optimizes both aspects together across multiple sub-channels, the system achieves better overall performance while using convex relaxation techniques to manage computational time efficiently.
Solution Approach 2:
The patent performs preliminary relaxation of the discrete sensor selection variables to continuous values before optimization, and establishes the convex optimization framework in advance. This preliminary action transforms the computationally difficult discrete problem into a tractable continuous problem that can be solved efficiently, reducing computational time while maintaining system performance.
3Productivity
If a sparse set of sub-channels is selected, then the computational complexity is reduced, but the signal isolation capability may be compromised
Solution Approach 1:
The patent extracts and selects only the most important active sub-channels from the complete set of possible sub-channels through the optimization process. By identifying and retaining only the essential sub-channels that contribute most to signal isolation while eliminating redundant ones, the system achieves sparsity that improves computational efficiency without significantly compromising signal isolation capability.
Solution Approach 2:
The patent applies different properties to different sub-channels by allowing the optimization to determine which specific sub-channels are active and what their individual filter responses should be. This local quality approach enables each selected sub-channel to be optimized for its specific frequency range and contribution to interference suppression, maintaining signal isolation capability while using fewer channels for improved computational efficiency.
Data Source
AI summary
Placement of microphones and design of filters in a microphone network are solved simultaneously. Using filterbanks with multiple sub-channels for each microphone, the design of the filter response is solved simultaneously with placement. By using an objective function that penalizes the number of sub-channels in any solution, only some of many possible sub-channels and corresponding microphones and filters are selected while also solving for the filter responses for the selected sub-channels. For a given target location, the location of the microphones and the filter responses to beamform are optimized.