Echo Compensation System Using Multi-Rate Sub-Band Processing
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Solution Overview
Problem
Existing echo compensation systems in communication systems fail to effectively reduce or eliminate echoes, leading to annoying user experiences and potential communication failures due to reflected sound signals.
Innovation Solution
An echo reduction system that converts input signals into sub-band signals, down-samples them using multiple rates, and processes them with echo analysis and compensation filters to generate estimated echo sub-band signals, which are then subtracted from the original signals to eliminate echoes, employing a signal analysis filter bank, echo analysis filter bank, and synthesis filter bank with specific down-sampling and up-sampling processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional echo compensation systems are used, then echoes are not effectively reduced, but the system complexity remains high
Solution Approach 1:
The patent divides the echo compensation system into separate functional modules: signal analysis filter bank, echo analysis filter bank, down-sampling circuits, and synthesis filter bank. Each module processes specific aspects of the signal independently, making the system more manageable and easier to optimize for echo reduction effectiveness.
Solution Approach 2:
The patent introduces multi-rate down-sampling and sub-band processing as additional dimensions to the traditional single-rate echo compensation approach. By processing signals at multiple sampling rates and dividing them into frequency sub-bands, the system achieves more effective echo reduction without being constrained by a single fixed processing rate.
2Reliability
If multi-rate down-sampling and sub-band processing is applied, then echo reduction effectiveness improves, but computational load increases
Solution Approach 1:
The patent segments the computational workload by processing different frequency sub-bands independently through separate filter banks. This allows the system to apply appropriate processing intensity to each sub-band, reducing overall computational load while maintaining effective echo reduction across the full frequency spectrum.
Solution Approach 2:
The patent uses multi-rate down-sampling to create additional processing dimensions. By down-sampling signals to lower sampling rates for sub-band processing, the system reduces computational complexity in higher frequency bands while maintaining accuracy through the hierarchical processing structure.
3Use of energy by moving object
If traditional single-rate processing is used, then computational requirements are lower, but aliasing and background noise increase
Solution Approach 1:
The patent introduces multi-rate down-sampling as an additional processing dimension that enables the system to separate echo components from background noise more effectively. By processing signals at multiple sampling rates, the system can identify and remove harmful components like aliasing and background noise that would be present in single-rate processing.
Solution Approach 2:
The patent uses down-sampled sub-band signals as intermediary representations that facilitate better separation of echo from non-echo components. These intermediary processed signals allow the system to identify and remove harmful factors like aliasing and background noise more effectively before final signal reconstruction.
Data Source
AI summary
An echo reduction system includes a signal analysis filter that converts an input into sub-band signals. A signal down-sampling circuit down-samples the sub-band signals at a first down-sampling rate. An echo analysis filter converts a loudspeaker signal into echo sub-band signal that are further processed by an echo down-sampling circuit. The circuit down-samples the echo sub-band signals at a second down-sampling rate to generate down-sampled echo sub-band signals. An echo compensation filter folds the down-sampled echo sub-band signals with an estimated impulse response of a loudspeaker-room-input system. A second echo down-sampling circuit down-samples the folded down-sampled echo sub-band signals at a third down-sampling rate to generate estimated echo sub-band signals. The first down-sampling rate is equal to the product of the second and third down-sampling rates.