Instability detection and avoidance in a feedback system
First Claim
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1. A feedback based active noise reduction system comprising:
- a feedback component for forming at least part of a feedback loop having an audio path segment, the feedback component includinga first signal input for accepting an input signal,a driver output for providing a driver signal to a driver of the audio path segment,a first feedback input for accepting a first feedback signal from a first sensor responsive to a signal on the audio path segment,a control input for accepting a control parameter for adjusting at least one of a gain characteristic and a phase characteristic of the feedback loop, andan instability detector for detecting an instability condition in the feedback component and forming the control parameter based on a result of the detection, the instability detector includinga feedback loop signal input for accepting a feedback loop signal,a circuit for detecting an oscillatory signal component in the feedback loop signal not represented in the input signal, the circuit including;
a circuit for forming a modified feedback loop signal, the circuit including circuitry for removing a component of the input signal from the feedback loop signal,a circuit for detecting the oscillatory signal component in a specified frequency range in the modified feedback loop signal, anda voltage controlled oscillator and a circuit for combining an output of the voltage controlled oscillator and the modified feedback loop signal, anda control parameter output for providing the control parameter to the control parameter input of the feedback element.
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Abstract
In an aspect, in general, a feedback based active noise reduction system is configured to detect actual or potential instability by detecting characteristics of the system related to potential or actual unstable behavior (e.g., oscillation) and adapt system characteristics to mitigate such instability.
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Citations
16 Claims
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1. A feedback based active noise reduction system comprising:
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a feedback component for forming at least part of a feedback loop having an audio path segment, the feedback component including a first signal input for accepting an input signal, a driver output for providing a driver signal to a driver of the audio path segment, a first feedback input for accepting a first feedback signal from a first sensor responsive to a signal on the audio path segment, a control input for accepting a control parameter for adjusting at least one of a gain characteristic and a phase characteristic of the feedback loop, and an instability detector for detecting an instability condition in the feedback component and forming the control parameter based on a result of the detection, the instability detector including a feedback loop signal input for accepting a feedback loop signal, a circuit for detecting an oscillatory signal component in the feedback loop signal not represented in the input signal, the circuit including; a circuit for forming a modified feedback loop signal, the circuit including circuitry for removing a component of the input signal from the feedback loop signal, a circuit for detecting the oscillatory signal component in a specified frequency range in the modified feedback loop signal, and a voltage controlled oscillator and a circuit for combining an output of the voltage controlled oscillator and the modified feedback loop signal, and a control parameter output for providing the control parameter to the control parameter input of the feedback element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for feedback based active noise reduction comprising:
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accepting, at a first signal input of a feedback component, an input signal, the feedback component forming at least part of a feedback loop having an audio path segment; providing, through a driver output of the feedback component, a driver signal to a driver of the audio path segment; accepting, at a first feedback input of the feedback component, a first feedback signal from a first sensor responsive to a signal on the audio path segment; accepting, at a control input of the feedback component, a control parameter for adjusting at least one of a gain characteristic and a phase characteristic of the feedback loop; and detecting an instability condition in the feedback component and forming the control parameter based on a result of the detection, detecting the instability condition including accepting, at a feedback loop signal input, a feedback loop signal, forming a modified feedback loop signal, including removing a component of the input signal from the feedback loop signal detecting an oscillatory signal component in the feedback loop signal, the oscillatory signal component not represented in the input signal, detecting the oscillatory signal component including forming a modified feedback loop signal, including removing a component of the input signal from the feedback loop signal, detecting the oscillatory signal component in a specified frequency range in the modified feedback loop signal, and combining an output of a voltage controlled oscillator and the modified feedback loop signal, and providing, through a control parameter output, the control parameter to the control parameter input of the feedback element. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification