System for active noise control with an infinite impulse response filter
First Claim
1. A computer-readable medium encoded with computer executable instructions, the computer executable instructions executable with a processor to operate an active noise control system, the computer-readable medium comprising:
- instructions executable to generate an output signal of an infinite impulse response filter based on an input signal representative of an undesired sound, the infinite impulse response filter comprising a plurality of cascaded filters;
instructions executable to generate an anti-noise signal based on the output signal of the infinite impulse response filter, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound;
instructions executable to generate an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the undesired sound and the sound waves produced by the speaker; and
instructions executable to independently update a plurality of coefficients included in each respective one of the cascaded filters of the infinite impulse response filter based on the update signal.
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Abstract
An active noise control (ANC) system includes at least one infinite impulse response filter (IIR). The IIR filter generates an output signal based on an input signal representative of an undesired sound. The ANC system generates an anti-noise signal based on the output signal of the IIR filter. The anti-noise signal is used to drive a speaker to generate sound waves to destructively interfere with the undesired sound. The ANC system includes an update system to generate update coefficients. The update system determines the stability of the update coefficients. Coefficients of the IIR filter are replaced with the update coefficients. The update system generates a set of update coefficients for each sample of the input signal.
187 Citations
25 Claims
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1. A computer-readable medium encoded with computer executable instructions, the computer executable instructions executable with a processor to operate an active noise control system, the computer-readable medium comprising:
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instructions executable to generate an output signal of an infinite impulse response filter based on an input signal representative of an undesired sound, the infinite impulse response filter comprising a plurality of cascaded filters; instructions executable to generate an anti-noise signal based on the output signal of the infinite impulse response filter, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound; instructions executable to generate an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the undesired sound and the sound waves produced by the speaker; and instructions executable to independently update a plurality of coefficients included in each respective one of the cascaded filters of the infinite impulse response filter based on the update signal. - View Dependent Claims (3, 4, 5)
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2. A computer-readable medium encoded with computer executable instructions, the computer executable instructions executable with a processor to operate an active noise control system, the computer-readable medium comprising:
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instructions executable to generate an output signal of an infinite impulse response filter based on an input signal representative of an undesired sound; instructions executable to generate an anti-noise signal based on the output signal of the infinite impulse response filter, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound; instructions executable to generate an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the undesired sound and the sound waves produced by the speaker, where the instructions executable to generate an update signal comprise; instructions executable to filter the output signal of the infinite impulse response filter with an estimated path filter to generate a filtered output signal; and instructions executable to sum the filtered output signal with the error signal to generate the update signal; and instructions executable to update a plurality of coefficients of the infinite impulse response filter based on the update signal.
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6. A computer-readable medium encoded with computer executable instructions, the computer executable instructions executable with a processor to operate an active noise control system, the computer-readable medium comprising:
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instructions executable to generate an output signal of an infinite impulse response filter based on an input signal representative of an undesired sound; instructions executable to generate an anti-noise signal based on the output signal of the infinite impulse response filter, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound; instructions executable to generate an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the undesired sound and the sound waves produced by the speaker; and instructions executable to update a plurality of coefficients of the infinite impulse response filter based on the update signal, wherein the instructions executable to update the plurality of filter coefficients comprise; instructions executable to determine a plurality of update coefficients, each update coefficient corresponding to one of the plurality of coefficients of the infinite impulse response filter; instructions executable to determine the stability of each of the update coefficients; and instructions executable to replace each of the plurality of coefficients of the infinite impulse response filter with corresponding update coefficients when each of the plurality of update coefficients is determined to be stable.
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7. A method of operating an active noise control system, the method comprising:
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generating an output signal of at least one infinite impulse response filter based on an input signal representative of an undesired sound, the infinite impulse response filter comprising a plurality of cascaded filters; generating anti-noise based on the output signal of the infinite impulse response filter; generating an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the anti-noise and the undesired sound; and independently updating a plurality of coefficients included in each respective one of the cascaded filters of the at least one infinite impulse response filter based on the output signal of the at least one infinite impulse response filter and the update signal. - View Dependent Claims (10, 11)
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8. A method of operating an active noise control system, the method comprising:
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generating an output signal of at least one infinite impulse response filter based on an input signal representative of an undesired sound; generating anti-noise based on the output signal of the infinite impulse response filter; generating an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the anti-noise and the undesired sound; updating a plurality of coefficients of the at least one infinite impulse response filter based on the output signal of the at least one infinite impulse response filter and the update signal; and filtering the output signal of the infinite impulse response filter with an estimated path filter to generate a filtered output signal; where, generating an update signal further comprises summing the filtered output signal with the undesired sound signal to generate the update signal. - View Dependent Claims (9)
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12. A method of operating an active noise control system, the method comprising:
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generating an output signal of at least one infinite impulse response filter based on an input signal representative of an undesired sound; generating anti-noise based on the output signal of the infinite impulse response filter; generating an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the anti-noise and the undesired sound; and updating a plurality of coefficients of the at least one infinite impulse response filter based on the output signal of the at least one infinite impulse response filter and the update signal by; determining a plurality of update coefficients, each of the update coefficients corresponding to a respective one of the plurality of coefficients of the infinite impulse response filter; determining the stability of each of the update coefficients; and replacing each of the plurality of coefficients of the infinite impulse response filter with corresponding update coefficients when each of the plurality of update coefficients is determined to be stable.
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13. An active noise control system comprising:
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a processor; and a memory connected to the processor, where the processor is configured to; generate an output signal from an infinite impulse response filter based on an input signal representative of an undesired sound, where the finite impulse response filter comprises a plurality of cascaded filters; generate an anti-noise signal based on the output signal of the infinite impulse response filter, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound; generate an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the undesired sound and the sound waves produced by the speaker; and independently update a plurality of coefficients included in each respective one of the cascaded filters of the infinite impulse response filter based on the update signal. - View Dependent Claims (15, 16, 17)
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14. An active noise control system comprising:
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a processor; and a memory connected to the processor, where the processor is configured to; generate an output signal from an infinite impulse response filter based on an input signal representative of an undesired sound; generate an anti-noise signal based on the output signal of the infinite impulse response filter, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound; filter the output signal of the infinite impulse response filter with an estimated path filter to generate a filtered output signal; generate an update signal based on summation of the filtered output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the undesired sound and the sound waves produced by the speaker; and update a plurality of coefficients of the infinite impulse response filter based on the update signal.
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18. An active noise control system comprising:
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a processor; and a memory connected to the processor, where the processor is configured to; generate an output signal from an infinite impulse response filter based on an input signal representative of an undesired sound; generate an anti-noise signal based on the output signal of the infinite impulse response filter, where the anti-noise signal is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound; generate an update signal based on the output signal of the infinite impulse response filter and an error signal representative of sound waves produced from a combination of the undesired sound and the sound waves produced by the speaker; update a plurality of coefficients of the infinite impulse response filter based on the update signal; determine a plurality of update coefficients, each of the update coefficients corresponding to a respective one of the plurality of coefficients of the infinite impulse response filter; determine the stability of each of the update coefficients; and replace each of the plurality of coefficients of the infinite impulse response filter with corresponding update coefficients when each of the plurality of update coefficients is determined to be stable.
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19. A method of operating an active noise control system, the method comprising:
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providing a first input signal sample representative of an undesired sound to an infinite impulse response filter, the infinite impulse response filter comprising a plurality of cascaded filters; generating an output signal sample of the infinite impulse response filter based on the first input signal sample; generating an anti-noise signal sample based on the output signal sample, where the anti-noise signal sample is configured to drive a speaker to produce sound waves to destructively interfere with an undesired sound; generating an error signal sample based on a combination of sound waves produced by the speaker and the undesired sound; generating an update signal sample based on the error signal sample; and updating a plurality of coefficients included in each respective one of the cascaded filters included in the infinite impulse response filter before a second input signal sample representative of the undesired sound is provided to the infinite impulse response filter. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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Specification