MSE variable step adaptive filter
AssigneeSperry Corporation
InventorsRichard W. Harris, Frank A. Bishop, Glen D. Rattlingourd
Life of this patent
Estimating the term…
Abstract
A very rapidly converging adaptive filter which uses a variable scale factor for each weight of the filter. The value of the variable scale factor is chosen for each iteration and is based upon the sign changes of the incremental weight change. The variable scale factor exhibits large values when no sign changes occur and smaller values when sign changes occur. The new filter provides considerable improvement in increase of convergence rate and decrease in residual errors even in the presence of heavy noise while requiring only a modest increase in hardware.
Claims29
Adaptive filter means comprising:
- input means for supplying an input signal,
- decorrelation means connected to said input means for producing a decorrelated signal,
- filter means for providing a filtered output signal,
- combining means for combining said input signal and said filtered output signal to produce a control signal,
- first scaling means connected to said combining means to receive said control signal and to said decorrelation means to received said decorrelated signal in order to produce a first scaling signal, and
- second scaling means connected to receive said control signal and said first scaling signal in order to supply a second scaling signal to said filter means to alter the operating characteristics thereof.
The system recited in claim wherein,
- said first scaling means includes detector means for detecting changes in the sign of said control signal.
A method of adaptive filtering comprising the steps of:
- providing a primary signal,
- decorrelating said primary signal in decorrelating apparatus in order to produce a decorrelated signal,
- producing a reference signal which is a function of said primary signal,
- summing said decorrelated signal with said reference signal to produce a n-bit control signal wherein n is greater than 1,
- supplying said control signal to one of a plurality of variable scaling elements of a weighting network associated with said decorrelating apparatus, and
- supplying fewer than n bits of said control signal to another of said plurality of variable scaling elements in order to alter said decorrelated signal produced by said decorrelating step in a variably adjustable fashion as a function of said control signal.
A filter circuit system comprising,
- an adaptable weight filter means (700) comprising a plurality of weighting networks each of which is adapted to receive an input signal (z(k)),
- first summing means (705) connected to said plurality of weighting networks to produce a filtered output signal (y(k)),
- said weighting networks each having a plurality of variable scale factor means (708,707), and
- second summing means (703) adapted to receive a reference input signal (d(k)) and said filtered output signal (y(k)) and to produce an error signal (e(k)) which is representative of the combination of said filtered output signal (y(k)) and said reference signal (d(k)),
- each of said plurality of variable scale factor means in each weighting network of said filter means connected to receive at least portions of said error signal (e(k)) and at least portions of said input signal (z(k)),
- wherein said variable scale factors of said variable scale factor means are a function of incremental changes of said error signal produced by said second summing means and said input signal.
Dependencies are inferred from the claim text.