Active noise reduction adaptive filtering
First Claim
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1. Apparatus comprising:
- a feed forward active noise reduction system comprisinga vehicle cabin;
a transducer for transducing acoustic noise in the vehicle cabin to a noise signal;
circuitry for determining the amplitude of the noise signal in a limited portion of the frequency range;
circuitry for comparing the amplitude of the noise signal in the limited portion of the frequency range with a limited frequency range threshold, wherein the limited frequency range is one ofbelow the frequency of the first amplitude peak of the engine noise, orbetween amplitude peaks of engine noise; and
circuitry for modifying the noise signal if the amplitude of the noise signal in the limited portion of the frequency range exceeds the limited frequency range threshold.
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Abstract
An active noise reduction system that reduces the incidence of divergence in the presence of high amplitude interfering noise. A limited frequency range threshold is established.
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Citations
27 Claims
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1. Apparatus comprising:
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a feed forward active noise reduction system comprising a vehicle cabin; a transducer for transducing acoustic noise in the vehicle cabin to a noise signal; circuitry for determining the amplitude of the noise signal in a limited portion of the frequency range; circuitry for comparing the amplitude of the noise signal in the limited portion of the frequency range with a limited frequency range threshold, wherein the limited frequency range is one of below the frequency of the first amplitude peak of the engine noise, or between amplitude peaks of engine noise; and circuitry for modifying the noise signal if the amplitude of the noise signal in the limited portion of the frequency range exceeds the limited frequency range threshold. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus comprising:
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a feed-forward active noise reduction system, comprising a transducer for transducing acoustic noise at a location to a noise signal; circuitry for determining the amplitude of the noise signal in a broadband frequency range; circuitry for comparing the amplitude of the noise signal in the broadband frequency range with a broadband threshold; circuitry for determining the amplitude of the noise signal over a limited portion of the broadband frequency range; circuitry for comparing the amplitude of the noise signal in the limited portion of the broadband frequency range with a limited frequency range threshold, wherein the limited frequency range is one of below the frequency of the first amplitude peak of the engine noise, or between amplitude peaks of engine noise; and circuitry for modifying the noise signal if the amplitude of the noise signal in the broadband frequency range exceeds the broadband threshold or the amplitude of the noise signal in the limited portion of broadband frequency range exceeds the limited frequency range threshold. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for operating a feed forward active noise reduction system, comprising:
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transducing acoustic noise in a vehicle cabin to a noise signal; determining the amplitude of the noise signal in a limited portion of the frequency range; comparing the amplitude of the noise signal in the limited portion of the frequency range with a limited frequency range threshold, wherein the limited frequency range is one of below the frequency of the first amplitude peak of noise resulting from operation of a vehicle engine, or between amplitude peaks of the noise resulting from the operation of the vehicle engine; and if the amplitude of the noise signal in the limited portion of the frequency range exceeds the limited frequency range threshold, modifying the noise signal. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A method for operating a feed-forward active noise reduction system, comprising:
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detecting acoustic energy at a location; transducing the acoustic noise to a noise signal; determining the amplitude of the noise signal in a broadband frequency range; comparing the amplitude of the noise signal in the broadband frequency range with a broadband threshold; determining the amplitude of the noise signal over a limited portion of the broadband frequency range; comparing the amplitude of the noise signal in the limited portion of the broadband frequency range with a limited frequency range, wherein the limited frequency range is one of below the frequency of a first amplitude peak of noise resulting from the operation of an engine, or between amplitude peaks of noise resulting from operation of the engine; and if the amplitude of the noise signal in the broadband frequency range exceeds the broadband threshold or the amplitude of the noise signal in the limited portion of the broadband frequency range exceeds the limited frequency range threshold, modifying the noise signal. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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Specification