Adaptive Filter Echo Cancellation Double-Talk
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing adaptive filters in telecommunications, particularly for Voice over IP (VoIP), face challenges in adapting to varying interference signals during double-talk conditions, where echo cancellation is compromised by the need to balance adaptation speed and avoiding coefficient detuning.
Innovation Solution
The method determines the level of a reference signal for adaptive filtering using a mathematical function based on the electrical power of signals from the transmission channel, incorporating powers from local subscriber signals, echo signals, and their differences, to estimate the echo signal effectively, allowing for precise adaptation and echo cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the adaptation speed of the adaptive filter is increased, then the filter adapts more quickly to echo path changes, but the filter is more prone to coefficient detuning during double-talk conditions
Solution Approach 1:
The patent implements dynamic adaptation by making the adaptation process itself adaptive through dual-mode operation. The system automatically switches between forced adaptation mode (for rapid echo path tracking) and natural adaptation mode (for stability during double-talk) based on real-time detection of double-talk conditions, thereby resolving the contradiction between adaptation speed and coefficient stability
Solution Approach 2:
The patent employs feedback mechanisms through double-talk detection that monitors the reference signal and adaptive filter output. When double-talk is detected, the system provides feedback to reduce or suspend adaptation, preventing coefficient detuning. This feedback loop enables the system to maintain high adaptation speed during single-talk while ensuring coefficient stability during double-talk periods
2Reliability
If the adaptation is continuously active to track echo path changes, then the echo cancellation performance is improved, but the adaptation process is disrupted by double-talk conditions causing incorrect coefficient updates
Solution Approach 1:
The patent segments the adaptation process into distinct operational modes: forced adaptation mode for rapid convergence during single-talk, and natural or suspended adaptation mode during double-talk. This segmentation allows the system to maintain accurate coefficients by preventing incorrect updates during double-talk while ensuring rapid adaptation during single-talk periods
Solution Approach 2:
The patent performs preliminary double-talk detection before coefficient updates are applied. By detecting double-talk conditions in advance and preemptively adjusting the adaptation process, the system prevents incorrect coefficient updates from occurring, thereby preserving coefficient accuracy and maintaining reliable echo cancellation performance
Data Source
Figure 1~2
AI summary
The invention relates to a method for adaptive filtering in which a level of a reference signal necessary for the adaptive filtering is determined in the context of an adaptation by estimation, using a quantity equivalent to the reference signal, wherein the filtering is dependent on the electrical power of at least one signal extracted from a transmission channel to be filtered, and the equivalent quantity is determined by means of a mathematical function based on the electrical power of at least the extracted signal. The invention further relates to an arrangement with means for carrying out the method.