Active acoustic attenuation system with power limiting
First Claim
1. An active acoustic attenuation method for attenuating an input acoustic wave comprising:
- introducing a canceling acoustic wave from an output transducer to attenuate said input acoustic wave and yield an attenuated output acoustic wave;
sensing said output acoustic wave with an error transducer and providing an error signal;
providing an adaptive filter model having an error input from the error signal and outputting a correction signal to said output transducer to introduce the canceling acoustic wave;
providing a shunt path around said output transducer;
preventing overdriving of said output transducer by shunting at least part of said correction signal to said shunt path and away from said output transducer.
1 Assignment
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Accused Products
Abstract
An active acoustic attenuation system prevents overdriving of the canceling output transducer or speaker (14) by shunting at least part of the correction signal (46) to a parallel shunt path (306) and away from the output transducer (14) Variable gains (308 and 310) are provided in the shunt path (306) and the input to the output transducer (14) for varying the ratio between the part of the correction signal (46) supplied to the output transducer (14) and the part of the correction signal (46) shunted to the shunt path (306). A first adaptive filter model (40) has an error input (202) from the error signal and outputs the correction signal (46). A second adaptive filter model (142) models the output transducer (14) and the error path (56) between the output transducer (14) and the error transducer (16). A copy (312) of the second model (142) has an input from the output (46) of the first model (40), and the output of the copy (312) is summed with the error signal (44) and the resultant sum is supplied to the error input (202) of the first model (40), such that the shunt path (306) is provided through the model copy (312).
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Citations
29 Claims
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1. An active acoustic attenuation method for attenuating an input acoustic wave comprising:
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introducing a canceling acoustic wave from an output transducer to attenuate said input acoustic wave and yield an attenuated output acoustic wave; sensing said output acoustic wave with an error transducer and providing an error signal; providing an adaptive filter model having an error input from the error signal and outputting a correction signal to said output transducer to introduce the canceling acoustic wave; providing a shunt path around said output transducer; preventing overdriving of said output transducer by shunting at least part of said correction signal to said shunt path and away from said output transducer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An active acoustic attenuation method for attenuating an input acoustic wave comprising:
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introducing a canceling acoustic wave from an output transducer to attenuate said input acoustic wave and yield an attenuated output acoustic wave; sensing said output acoustic wave with an error transducer and providing an error signal; providing a first adaptive filter model having an error input from the error signal and outputting a correction signal to said output transducer to introduce the canceling acoustic wave; providing a second adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer; providing a copy of said second model; providing an input to said copy from the output of said first model; summing the output of said copy with said error signal and supplying the resultant sum to said error input of said first model. - View Dependent Claims (12, 13, 14)
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15. An active acoustic attenuation system for attenuating an input acoustic wave comprising:
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an output transducer introducing a canceling acoustic wave to attenuate said input acoustic wave and yield an attenuated output acoustic wave; an error transducer sensing said output acoustic wave and providing an error signal; an adaptive filter model having an error input from the error signal and outputting a correction signal to said output transducer to introduce the canceling acoustic wave; a shunt path around said output transducer and preventing overdriving of said output transducer by shunting at least part of said correction signal to said shunt path and away from said output transducer. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. An active acoustic attenuation system for attenuating an input acoustic wave comprising:
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an output transducer introducing a canceling acoustic wave to attenuate said input acoustic wave and yield an attenuated output acoustic wave; an error transducer sensing said output acoustic wave and providing an error signal; a first adaptive filter model having an error input from the error signal and outputting a correction signal to said output transducer to introduce the canceling acoustic wave; a second adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer; a copy of said second model having an input from the output of said first model; a summer summing the output of said copy with said error signal and supplying the resultant sum to said error input of said first model. - View Dependent Claims (23, 24, 25)
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26. An active acoustic attenuation system for attenuating an input acoustic wave comprising:
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an output transducer introducing a canceling acoustic wave to attenuate said input acoustic wave and yield an attenuated output acoustic wave; an error transducer sensing said output acoustic wave and providing an error signal; a first adaptive filter model having an error input from the error signal and outputting a correction signal to said output transducer to introduce the canceling acoustic wave, said first adaptive filter model comprising; a first algorithm filter having a filter input, a filter output, and an error input from said error transducer; a second algorithm filter having a filter input from said correction signal, a filter output, and an error input from said error transducer; and a first summer having a first input from said filter output of said first algorithm filter, a second input from said filter output of said second algorithm filter, and an output outputting a resultant sum as said correction signal; a second adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer; a first copy of said second model, said first copy having an input from said filter input of said first algorithm filter, and having an output to said error input of said first algorithm filter; a second copy of said second model, said second copy having an input from said correction signal, and having an output to said error input of said second algorithm filter; a shunt path around said output transducer and preventing overdriving of said output transducer by shunting at least part of said correction signal to said shunt path and away from said output transducer, said shunt path including said second copy. - View Dependent Claims (27, 28, 29)
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Specification