Adaptive Delay Diversity Filtering for Variable Echo Delays
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Solution Overview
Problem
Existing adaptive filters face challenges in efficiently canceling echoes due to varying time delays between speaker output and microphone input signals, particularly when large changes occur in the signal travel path, leading to increased computational load and longer convergence times.
Innovation Solution
An adaptive delay diversity filter using multiple sub-filters that share calculation values and adjust their number through a pruning method, allowing efficient echo cancellation with a short filter length and reduced computational load, even with large variations in time delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filter length is increased to cope with large time delay variation, then the echo cancellation capability is improved, but the convergence time becomes longer and computational load increases
Solution Approach 1:
The patent divides the long filter into multiple sub-filters, each handling a specific time delay range. This segmentation allows the system to process echoes with varying delays efficiently without requiring a single excessively long filter, thereby reducing convergence time while maintaining echo cancellation capability.
Solution Approach 2:
The patent dynamically selects and activates sub-filters based on the actual time delay conditions. By adaptively adjusting which sub-filters are active, the system optimizes performance for current echo conditions without the computational burden of maintaining all sub-filters active, thus reducing computational load while preserving reliability.
2Reliability
If the filter length is increased to cope with large time delay variation, then the echo cancellation capability is improved, but the computational load increases
Solution Approach 1:
The patent segments the filtering operation into multiple independent sub-filters that can be selectively activated. This allows the computational load to be distributed and optimized based on actual needs, preventing the excessive computational burden that would result from a single long filter processing all delay variations.
Solution Approach 2:
The patent changes the operational parameters by adjusting which sub-filters are active based on detected time delay characteristics. This dynamic parameter adjustment enables the system to maintain high echo cancellation performance while adapting computational resources to match actual requirements, thereby reducing overall computational load.
3Adaptability or versatility
If multiple sub-filters are used to handle time delay variation, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The patent organizes multiple sub-filters into a structured array where each sub-filter handles a specific portion of the time delay range. This segmentation provides adaptability to various delay conditions while maintaining a systematic and manageable structure, avoiding the chaos that would result from an unorganized multi-filter approach.
Solution Approach 2:
The patent designs sub-filters with shared computational components and structures that can be reused across different sub-filters. This multi-functionality approach allows the system to handle diverse time delay variations using a standardized framework, reducing the overall complexity that would arise from completely independent filter designs.
Data Source
Figure 1~2A
Figure 2B
Figure 3A~3B
AI summary
The present invention relates to a new type of adaptive filter and an echo cancellation apparatus and method using the same, and discloses an adaptive delay diversity filter for coping with the situation in which variation in a time delay between a reference signal and a target signal of an adaptive filter is large. The adaptive delay diversity filter includes multiple sub-filters, each of which generates output through filtering by utilizing a signal, obtained by applying different time delay values to the reference signal, as a reference signal, and selects the best output value among generated output values of the multiple sub-filters, as an output value of the adaptive delay diversity filter. Further, the adaptive delay diversity filter includes a means for reducing a computational load.