Training a recursive filter by use of derivative function
First Claim
1. A method of adapting a filter having a plurality of recursive filter parameters, said recursive filter effective for producing an output signal in response to receiving an input signal, the method comprising:
- subtracting said output signal from a desired signal to produce an error signal;
producing a plurality of derivative functions, each of whose level is representative of derivative of said output signal with respect to a particular recursive filter parameter; and
updating each of said recursive filter parameters based on said derivative functions and said error signal.
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Abstract
A method of training a recursive filter comprises updating recursive parameters of the filter with delta values computed from sampling of an error signal and obtaining derivative terms of the output signal with respect to the parameters. Adaptation using derivatives for FIR filters is known, but this technique was not available for IIR filters because of the unavailability of the derivative values. However, when it is realized that the derivative itself is recursive, a parameter derivative function is obtained which will produce derivative terms for updating the filter parameters with acceptable filter performance.
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Citations
14 Claims
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1. A method of adapting a filter having a plurality of recursive filter parameters, said recursive filter effective for producing an output signal in response to receiving an input signal, the method comprising:
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subtracting said output signal from a desired signal to produce an error signal; producing a plurality of derivative functions, each of whose level is representative of derivative of said output signal with respect to a particular recursive filter parameter; and updating each of said recursive filter parameters based on said derivative functions and said error signal. - View Dependent Claims (2, 3, 4, 5)
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6. A method of adapting a filter having a plurality of recursive and non-recursive parameters, said filter effective for producing an output signal in response to receiving an input signal, the method comprising:
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subtracting said output signal from a desired signal to produce an error signal; producing a plurality of derivative functions, each of whose level is representative of derivative of said output signal with respect to a particular recursive parameter; and producing a plurality of derivative functions, each of whose level is representative of derivative of said output signal with respect to a particular non-recursive parameter; and updating each said recursive and non-recursive parameter based upon its corresponding derivative function and said error signal. - View Dependent Claims (7, 8, 9, 10)
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11. An adaptive recursive filter comprising:
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input means for obtaining an input signal; computing means, coupled to said input means, for producing an output signal, said computing means characterized by a plurality of recursive parameters; error means, coupled to said computing means, for comparing said output signal with a desired output signal; derivative function means for producing a plurality of signals, each signal representative of a derivative of said output signal with respect to one of said recursive filter parameters; update means, coupled to said error means and said derivative function means, for updating said plurality of recursive parameters. - View Dependent Claims (12, 13, 14)
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Specification