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US 6,744,886 B1Granted
Adaptive filter utilizing proportional affine projection algorithm
AssigneeLucent Technologies Inc.
InventorsJacob Benesty, Tomas Fritz Gaensler, Steven Leslie Gay, Man Mohan Sondhi
Life of this patent
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Abstract
An adaptive filter suitable for network echo cancellation and other applications contains a coefficient vector update device for feeding coefficient vector updates to a finite impulse response filter in accordance with fast converging algorithms. A double talk detector is included for causing filter adaptation to cease in the presence of double talk in the system being echo cancelled. The coefficient vector update device utilizes a proportional affine projection algorithm to provide fast convergence of the filter system and improved performance over other filter devices utilizing different fast converging algorithms.
Claims5
An adaptive filter comprising:
- a finite impulse response filter;
- and
- a coefficient vector update device connected to said finite impulse response filter for feeding adaptive coefficients in accordance with the application of a fast converging adaptive filter algorithm to said filter in response to samples of a received error signal, said update device alternately applying a PNLMS algorithm and an APA algorithm at each successive sample of said error signal.
An echo canceller for a telephone network, comprising:
- a finite impulse response filter connected to said telephone circuit;
- and
- a coefficient vector update device connected to said finite impulse response filter for feeding adaptive coefficients in accordance with the application of a fast converging adaptive filter algorithm to said filter in response to samples of a received echo signal, said update device alternately applying a PNLMS algorithm and an APA algorithm at each successive sample of said echo signal;
- and
- a double talk detector connected to said telephone circuit for disabling said update device in response to the detection of double talk on said circuit.
2 more elements
An adaptive filter comprising:
- a finite impulse response filter;
- and
- a coefficient vector update device connected said finite impulse response filter for feeding adaptive coefficients thereto in response to a received error signal, said coefficients given by
- hn+1=hn+μGnXn(XnTXn+δI)−1en, and
- R xx , n - 1 = [ r11 , n r12 , n r12 , n r22 , n ] - 1 = ( X n T X n + δ I ) - 1 ,
- where h is an estimated echo path vector, μ is a step size variable, G is a diagonal matrix that dynamically adjusts step-sizes of individual filter taps, X is an excitation matrix, δ is a parameter that prevents division by zero, I is the identity matrix, e is a residual echo vector, Rxx is a correlation matrix, r is a correlation coefficient, and x and n are integers,
- wherein the matrix G has diagonal elements calculated by the equations:
- Gn=diag{g0,n, . . . , gL−1,n},
- Lmax=max{δp |ho,n−1|, . . . , |hl−1,n−1|},
- γi=max{ρLmax, |hi,n−1|}, 0≦i≦L−1,
- L 1 = ∑ i = 0 L - 1 γ i , gi=γi/L1
- where δp and ρ are positive numbers.
9 more elements
An adaptive filter comprising:
- a finite impulse response filter;
- and
- a coefficient vector update device connected to said finite impulse response filter for feeding adaptive coefficients in accordance with the application of a fast conversing adaptive filter algorithm to said filter in response to samples of a received error signal, said update device applying a proportional affine projection algorithm where the proportional affine projection algorithm uses adaptive filter coefficients defined by:
- hn+1=hn+μGnXn(XnTXn+δI)−1en, and
- R xx , n - 1 = [ r11 , n r12 , n r12 , n r22 , n ] - 1 = ( X n T X n + δ I ) - 1 ,
- where h is an estimated echo path vector, μ is a step size variable, G is a diagonal matrix that dynamically adjusts step-sizes of individual filter taps, X is an excitation matrix, δ is a parameter that prevents division by zero, I is the identity matrix, e is a residual echo vector, Rxx is a correlation matrix, r is a correlation coefficient, and x and n are integers,
- wherein the matrix G has diagonal elements calculated by the equations:
- Gn=diag{g0,n, . . . , gL−1,n},
- Lmax=max{δp |ho,n−1|, . . . , |hl−1,n−1|},
- γi=max{ρLmax, |hi,n−1|}, 0≦i≦L−1,
- L 1 = ∑ i = 0 L - 1 γ i , gi=γi/L1
- where δp and ρ are positive numbers.
9 more elements
An echo canceller for a telephone network, comprising:
- a finite impulse response filter connected to telephone circuit;
- and
- a coefficient vector update device connected top said finite impulse response filter for feeding adaptive coefficients in accordance with the application of a fast converging adaptive filter algorithm to said filter in response to samples of a received echo signal, said update device applying a proportional affine projection algorithm;
- and
- a double talk detector connected to said telephone circuit for disabling said update device in response to the detection of double talk on said circuit, where the proportional affine projection algorithm uses adaptive filter coefficients defined by:
- hn+1=hn+μGnXn(XnTXn+δI)−1en, and
- R xx , n - 1 = [ r11 , n r12 , n r12 , n r22 , n ] - 1 = ( X n T X n + δ I ) - 1 ,
- where h is an estimated echo path vector, μ is a step size variable, G is a diagonal matrix that dynamically adjusts step-sizes of individual filter taps, X is an excitation matrix, δ is a parameter that prevents division by zero, I is the identity matrix, e is a residual echo vector, Rxx is a correlation matrix, r is a correlation coefficient, and x and n are integers,
- wherein the matrix G has diagonal elements calculated by the equations:
- Gn=diag{g0,n, . . . , gL−1,n},
- Lmax=max{δp |ho,n−1|, . . . , |hl−1,n−1|},
- γi=max{ρLmax, |hi,n−1|}, 0≦i≦L−1,
- L 1 = ∑ i = 0 L - 1 γ i , gi=γi/L1
- where δp and ρ are positive numbers.
11 more elements
Dependencies are inferred from the claim text.