Active Noise Reduction Controller Filter Update Timing
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Solution Overview
Problem
Existing active noise reduction systems face high calculation loads during filter updates, leading to increased manufacturing costs due to the need for expensive processors.
Innovation Solution
The system differentiates the timing of adaptive updates for the control filter and secondary path filter, reducing the calculation load on the controller and eliminating the need for expensive processors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adaptive update of the control filter and the adaptive update of the secondary path filter are performed simultaneously, then the noise reduction performance is maintained, but the calculation load on the controller becomes large
Solution Approach 1:
The patent segments the filter update process by separating the adaptive update of the control filter from the adaptive update of the secondary path filter in time. The controller performs updates in alternating phases: in one phase it updates the control filter while keeping the secondary path filter fixed, and in another phase it updates the secondary path filter while keeping the control filter fixed. This temporal segmentation reduces the simultaneous calculation load while maintaining overall system performance.
2Reliability
If the adaptive update of the control filter and the adaptive update of the secondary path filter are performed simultaneously, then the filter convergence is maintained, but expensive processors are required
Solution Approach 1:
The patent applies temporal segmentation to divide the filter update operations into separate phases. During each phase, only one filter type undergoes adaptive update while the other remains fixed, reducing the real-time computational requirements. This allows the use of less expensive processors that can handle the reduced calculation load while still achieving filter convergence through repeated alternating updates.
Data Source
AI summary
An active noise reduction system includes a canceling sound output device configured to output a canceling sound, an error microphone configured to generate an error signal, and a controller configured to control the canceling sound output device based on the error signal. The controller includes a control signal generation unit including a control filter configured to generate a control signal for controlling the canceling sound output device, and a sound field learning unit including a secondary path filter that represents an estimation value of a transfer function of a secondary path from the canceling sound output device to the error microphone, the control filter and the secondary path filter are configured to be adaptively updated, and the controller is configured to differentiate a timing of an adaptive update of the control filter and a timing of an adaptive update of the secondary path filter.