Instability detection and avoidance in a feedback system

摘要

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.

主权项

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 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, 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.