Adaptive recursive least mean square error filter
First Claim
1. An adaptive filter comprising:
- first means for receiving a first input signal;
a first adaptive transversal fiter, coupled to said first means, being responsive to the first input signal for developing a first filter signal;
a second adaptive transversal filter responsive to an output signal of the adaptive recursive filter for developing a second filter signal;
second means for combining the first and second filter signals to form said output signal;
third means for receiving the second input signal;
fourth means coupled to said second and third means for combining the second input signal with the output signal to generate an error signal; and
fifth means responsive to the error signal for causing said first and second transversal filters to adaptively modify the first and second filter signals to minimize the mean square error in the output signal.
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Abstract
An adaptive recursive filter is disclosed which, in a preferred embodiment, comprises first and second adaptive transversal filters selectively coupled together to minimize the mean square error of the output data of the recursive filter based upon observations of input data to the recursive filter. Each transversal filter includes a tapped delay line with a variable weight on each tap. The output data of the recursive filter is developed by combining the outputs of the first and second transversal filters. The input data is applied to the first transversal filter, while the output data is applied to the second transversal filter. The output data is also combined with a reference signal to provide an error signal. A function of that error signal is utilized to update the weights of all of the taps in both transversal filters in order to cause the weights to automatically adapt themselves to minimize the mean square error of the output data of the recursive filter.
146 Citations
17 Claims
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1. An adaptive filter comprising:
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first means for receiving a first input signal; a first adaptive transversal fiter, coupled to said first means, being responsive to the first input signal for developing a first filter signal; a second adaptive transversal filter responsive to an output signal of the adaptive recursive filter for developing a second filter signal; second means for combining the first and second filter signals to form said output signal; third means for receiving the second input signal; fourth means coupled to said second and third means for combining the second input signal with the output signal to generate an error signal; and fifth means responsive to the error signal for causing said first and second transversal filters to adaptively modify the first and second filter signals to minimize the mean square error in the output signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A machine method for rendering a recursive filter adaptive comprising the steps of:
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combining the filter output signal with a first input signal to develop an error signal; and utilizing the filter output signal, a second input signal and the error signal to enable the filter to automaticaly adapt itself to minimize the mean square error in the filter output signal.
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8. A machine method for enabling a recursive filter to automatically adapt comprising the steps of:
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combining the filter output signal with a first input signal to develop an error signal; generating a function of the error signal; and enabling the filter to minimize the mean square error in the output signal in response to a second input signal, the output signal and to the function of the error signal.
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9. A machine method for causing a recursive filter to automatically adapt comprising the steps of:
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combining a first input signal with the output signal from the recursive filter to develop an error signal; scaling the error signal; and applying a second input signal, the output signal and the scaled error signal to the filter to enable the filter to automatically adapt itself to minimize the mean square error in the ouput signal.
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10. A machine method for enabling a recursive filter to automatically adapt comprising the steps of:
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combining the output signal of the filter with a first input signal to develop an error signal; developing at last one function signal from the error signal; utilizing a second input signal, the output signal and said at least one function signal to cause the recursive filter to automatically adapt itself to minimize the mean square error in the output signal. - View Dependent Claims (11, 12, 13)
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14. A machine method for making a recursive filter adaptive comprising the steps of:
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providing a first input signal to a first transversal filter; combining the output of the first transversal filter with the output of a second transversal filter to develop the output signal to the recursive filter; feeding back the output signal to the second transversal filter; enabling a second input signal to be combined with the output signal to develop an error signal; utilizing the error signal to develop at least one function signal; and applying said at least one function signal to the first and second transversal filter to enable the first and second transversal filters to automatically adapt themselves to minimize the mean square error in the output signal. - View Dependent Claims (15, 16, 17)
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Specification