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US 8,194,873 B2Granted
Active noise reduction adaptive filter leakage adjusting
OwnerDavis Pan, Christopher J. Cheng +1inventors
InventorsDavis Pan, Christopher J. Cheng, Eduardo Salvador
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Abstract
An active noise reduction system using adaptive filters. A method of operation the active noise reduction system includes smoothing a stream of leakage factors. The frequency of a noise reduction signal may be related to the engine speed of an engine associated with the system within which the active noise reduction system is operated. The engine speed signal may be a high latency signal and may be obtained by the active noise reduction system over audio entertainment circuitry.
Claims26
A method comprising:
- in a vehicle comprising an active noise reduction system, providing filter coefficients for an adaptive filter in response to a noise signal;
- determining leakage factors wherein the determining provides leakage factors with one of a plurality of values dependent on the presence or absence of a plurality of triggering conditions exclusive of the values of the leakage factors;
- subsequent to the determining, smoothing the leakage factors to provide smoothed leakage factors to prevent abrupt changes in the leakage factors;
- applying the smoothed leakage factors to the filter coefficients to provide modified filter coefficients;
- and
- responsive to the modified filter coefficients, providing an active noise reduction signal characterized by a magnitude.
3 more elements
Apparatus comprising:
- active noise reduction system for use in a vehicle, comprising
- an adaptive filter, for providing an active noise reduction signal;
- a coefficient calculator, for providing filter coefficients for the adaptive filter;
- a leakage determiner for providing a stream of leakage factors, wherein the leakage determiner comprises
- a plurality of detectors for detecting the presence or absence of a plurality of triggering conditions exclusive of the value of the leakage factor;
- and
- a selector, for selecting one of a plurality of leakage factors each of the plurality of leakage factors corresponding to the presence of one of the triggering conditions;
- and
- the active noise reduction system further comprising a leakage adjuster comprising a leakage factor data smoother separate from the leakage determiner to smooth the stream of leakage factors to prevent abrupt changes in the leakage factors;
- wherein one of the plurality of detectors comprises circuitry for comparing the active noise reduction signal magnitude to a threshold.
7 more elements
Dependencies are inferred from the claim text.