Methods and systems for determining the effectiveness of active noise cancellation
First Claim
1. A method for controlling a noise cancellation system having an adaptive control portion, the noise cancellation system operable to generate a cancellation noise configured to at least partially cancel an unwanted noise in a defined environment, and the adaptive control portion operable to adjust the operation of the noise cancellation system based on a remaining level of unwanted noise remaining when the cancellation noise and the unwanted noise are combined, the method comprising:
- receiving an error signal representing a portion of a noise not cancelled by a cancellation noise generated from the noise cancellation system;
determining whether the level of the error signal exceeds a first threshold value for a first predetermined period of time;
calculating a crest factor using the error signal, the crest factor representing the ratio of a peak value of the error signal to the root-mean-square value of the error signal;
determining whether the crest factor exceeds a second threshold value; and
deactivating the adaptive control portion and continuing to operate the noise cancellation system if the error value exceeds the first threshold value for the predetermined period of time and the crest factor exceeds the second threshold value.
1 Assignment
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Accused Products
Abstract
A method for controlling a noise cancellation system having an adaptive control portion is provided. The noise cancellation system is operable to generate a cancellation noise configured to at least partially cancel an unwanted noise in a defined environment. The adaptive control portion is operable to adjust the operation of the noise cancellation system based on a level of unwanted noise that remains when the cancellation noise and the unwanted noise are combined. The method includes receiving an error signal representing a portion of a noise not cancelled by a cancellation noise, where the cancellation noise is generated from the noise cancellation system. The method also includes determining whether the level of the error signal exceeds a first threshold value for a first predetermined period of time. The method also includes calculating a crest factor using the error signal. The method also includes determining whether the crest factor exceeds a second threshold value. The method also includes deactivating the adaptive control system and continuing to operate the noise cancellation system if the error value exceeds the first threshold value for the predetermined period of time and the crest factor exceeds the second threshold value.
51 Citations
20 Claims
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1. A method for controlling a noise cancellation system having an adaptive control portion, the noise cancellation system operable to generate a cancellation noise configured to at least partially cancel an unwanted noise in a defined environment, and the adaptive control portion operable to adjust the operation of the noise cancellation system based on a remaining level of unwanted noise remaining when the cancellation noise and the unwanted noise are combined, the method comprising:
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receiving an error signal representing a portion of a noise not cancelled by a cancellation noise generated from the noise cancellation system; determining whether the level of the error signal exceeds a first threshold value for a first predetermined period of time; calculating a crest factor using the error signal, the crest factor representing the ratio of a peak value of the error signal to the root-mean-square value of the error signal; determining whether the crest factor exceeds a second threshold value; and deactivating the adaptive control portion and continuing to operate the noise cancellation system if the error value exceeds the first threshold value for the predetermined period of time and the crest factor exceeds the second threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for controlling a noise cancellation system operable to generate a cancellation noise configured to at least partially cancel an unwanted noise in a defined environment, the system comprising:
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a computer having a microprocessor and computer-readable medium coupled to the microprocessor; and a program stored in the computer-readable medium, the program, when executed by the microprocessor, operable to; receive an error signal representing a portion of a noise not cancelled by a cancellation noise generated from the noise cancellation system, the cancellation noise configured to at least partially cancel the noise; determine whether the level of the error signal exceeds a first threshold value for a predetermined period of time; calculating a crest factor using the error signal, the crest factor representing the ratio of a peak value of the error signal to the root-mean-square value of the error signal; determine whether the crest factor exceeds a second threshold value; and deactivate an adaptive control portion of the noise cancellation system while continuing to operate the noise cancellation system if the error value exceeds the first threshold value for the predetermined period of time and the crest factor exceeds the second threshold value, the adaptive control portion, when in operation, operable to monitor the performance of the noise cancellation system and, based on the monitoring, to adjust the operation of the noise cancellation system. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for controlling a noise cancellation system having an adaptive control portion, the noise cancellation system operable to generate a cancellation noise configured to substantially cancel an unwanted noise within a compartment of a vehicle, and the adaptive control portion operable to adjust the operation of the noise cancellation system based on a remaining level of unwanted noise remaining when the cancellation noise and the unwanted noise is combined, the method comprising:
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receiving an error signal representing a portion of a noise not cancelled by a cancellation noise generated from the noise cancellation system, the cancellation noise configured to substantially cancel the noise; determining whether the magnitude of the error signal exceeds a first threshold value for a predetermined period of time; calculating a crest factor using the error signal, the crest factor representing the ratio of a peak value of the error signal to the root-mean-square value of the error signal; determining whether the crest factor exceeds a second threshold value; determining whether the noise cancellation system is unstable, wherein the noise cancellation system is unstable when the level of the noise is increasing while the level of the cancellation noise is also increasing; deactivating the adaptive control portion and continuing to operate the noise cancellation system if the error value exceeds both the first threshold value for the predetermined period of time and the crest factor exceeds the second threshold value; and deactivating the noise cancellation system if the noise cancellation system is not unstable and the crest factor does not exceed the second threshold value.
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Specification