Active Noise Reduction Filter Saturation Correction
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Solution Overview
Problem
Conventional active-noise-reduction systems face saturation of filter coefficients when dealing with large noise levels, leading to a reduction in noise reduction effectiveness.
Innovation Solution
An active-noise-reduction device that includes a reference signal generating unit, an adaptive filter unit, a correction unit, a filter coefficient update unit, and an amplitude adjustment unit, which uses simulated acoustic transfer characteristics data to correct the reference signal and update filter coefficients, and adjusts the amplitude of the cancelling signal to prevent saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adaptive filter unit processes large noise levels, then the noise reduction capability is improved, but the filter coefficient saturation occurs leading to reduced effectiveness
Solution Approach 1:
The correction unit acts as an intermediary between the reference signal generating unit and the adaptive filter unit. It corrects the reference signal using simulated acoustic transfer characteristics data before it reaches the adaptive filter, preventing filter coefficient saturation while maintaining noise reduction effectiveness for large noise levels
Solution Approach 2:
The system performs preliminary correction of the reference signal using simulated acoustic transfer characteristics data before the adaptive filter processes it. This preliminary action prepares the reference signal to avoid causing filter coefficient saturation during subsequent noise cancellation operations
2Reliability
If the filter coefficient is continuously updated to reduce error signal, then the noise reduction performance is improved, but the filter coefficient saturation occurs
Solution Approach 1:
The correction unit serves as a mediator that modifies the reference signal to account for acoustic transfer characteristics. This prevents the filter coefficient update process from causing saturation, thereby maintaining both noise reduction performance and filter coefficient stability
Solution Approach 2:
The system uses error signal feedback to continuously update the filter coefficient, but the correction unit pre-processes the reference signal to ensure this feedback loop doesn't lead to saturation. This maintains stable filter coefficient operation while achieving effective noise reduction
Data Source
AI summary
A reference signal generating unit of an active-noise-reduction device of the present invention outputs a referencing signal having a correlation with a vibration to an adaptive filter unit. A filter coefficient update unit receives an input of an error signal, and successively updates a filter coefficient of the adaptive filter unit. The error signal is generated by a cancelling sound based on the output of the adaptive filter unit and noise. The detection unit detects a filter coefficient of the filter coefficient update unit, and determines a size of the output of the adaptive filter unit. Then, the amplitude of the cancelling sound is adjusted based on the size of the output of the adaptive filter unit estimated by the detection unit.