Noise Cancellation Circuit Parallel Filter Convergence
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Solution Overview
Problem
Conventional sound input and output systems with hybrid noise cancellation face issues with slow convergence of filter coefficients, affecting the adaptive noise cancellation performance.
Innovation Solution
The system includes a noise cancellation circuit with a signal processing circuit that generates feedback signals and filters them using second filter coefficients, and scale update circuits that adjust scales and filter coefficients using algorithms like steepest descent to improve convergence speed and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filter coefficients are updated frequently to improve adaptive noise cancellation performance, then the noise cancellation effectiveness is improved, but the convergence speed becomes slow and convergence performance deteriorates
Solution Approach 1:
The patent segments the filter coefficient update process into multiple parallel channels: a first filter circuit processes coefficients for feedforward noise cancellation, while a second filter circuit processes coefficients for feedback noise cancellation. Additionally, multiple microphones (first and second microphones) capture different noise signals independently. This segmentation allows each channel to converge independently and faster, then combine results for overall noise cancellation.
Solution Approach 2:
The patent implements dynamic adaptation by continuously updating filter coefficients based on real-time noise signals captured by microphones. The system dynamically adjusts the feedforward and feedback filter coefficients separately through their respective filter circuits, allowing the system to adapt to changing noise environments while maintaining fast convergence through independent parallel processing of each adaptive channel.
2Reliability
If the filter coefficients are updated frequently to improve adaptive noise cancellation performance, then the noise cancellation effectiveness is improved, but the convergence performance becomes poor
Solution Approach 1:
The patent divides the convergence process into separate parallel paths: the first filter circuit converges feedforward coefficients independently while the second filter circuit converges feedback coefficients independently. This segmentation prevents interference between different coefficient types during convergence, improving overall convergence performance and accuracy.
Solution Approach 2:
The patent employs feedback mechanisms where the second microphone captures the output sound from the speaker and feeds it back through the second filter circuit to continuously refine the feedback coefficients. This feedback loop enables precise convergence by constantly adjusting coefficients based on actual system output, improving convergence performance through iterative refinement.
Data Source
AI summary
A noise cancellation circuit includes: a first filter circuit for filtering a first input signal according to a first filter coefficient to generate a first filtered signal; a signal processing circuit for generating a feedback signal according to a second input signal and an audio signal; a second filter circuit for filtering the feedback signal according to a second filter coefficient to generate a second filtered signal; a first multiplication circuit for multiplying the first filtered signal by a first scale to generate a first intermediate signal; a second multiplication circuit for multiplying the second filtered signal by a second scale to generate a second intermediate signal; a first adder circuit for adding the first intermediate signal to the second intermediate signal to generate a noise cancellation signal; and a second adder circuit for adding the noise cancellation signal to the audio signal to generate an output signal.