Adaptive filter for network echo cancellation

A robust adaptive filter comprising:

• an adaptive filter utilizing a fast converging adaptive algorithm;
• means for modifying said algorithm by the application thereto of an adaptive scaled non-linearity;
• and
• a double talk detector connected to said adaptive filter for disabling said adaptive filter in response to the detection of double talk on a telephone circuit wherein the fast converging algorithm is PNLMS++.

A robust adaptive filter comprising:

• an adaptive filter utilizing a fast converging adaptive algorithm;
• means for modifying said algorithm by the application thereto of an adaptive scaled non-linearity;
• and
• a double talk detector connected to said adaptive filter for disabling said adaptive filter in response to the detection of double talk on a telephone circuit, said double talk detector also connected to said modifying means for controlling adaptation of said adaptive scaled non-linearity so as to reduce the impact of double talk on said filter by reducing divergence in a period of undetected double talk;
• wherein the fast converging algorithm is APA.

A robust adaptive filter comprising:

• an adaptive filter utilizing a fast converging adaptive algorithm;
• means for modifying said algorithm by the application thereto of an adaptive scaled non-linearity;
• and
• a double talk detector connected to said adaptive filter for disabling said adaptive filter in response to the detection of double talk on a telephone circuit;
• wherein the fast converging algorithm is PAPA.

A robust echo canceller comprising:

• an adaptive filter for outputting an error signal in response to a detected echo signal;
• and
• means for supplying adaptive filter coefficients to said filter, wherein said filter coefficients are given by the formula:
• h
• n
• +
• 1
• =
• h
• n
• +
• π
• x
• n
• T
• ⁢
• G
• n
• ⁢
• x
• n
• +
• δ
• ⁢
• G
• n
• ⁢
• x
• n
• ⁢
• φ
• ⁡
• (
• 
• e
• n
• 
• )
• ⁢
• sign
• ⁢
• {
• e
• n
• }
• ,
• wherein hn is the estimated echo path;
• μ is the overall step size parameter;
• Gn is the excitation matrix;
• xn is the excitation vector;
• δ is the regularization parameter that prevents division by zero;
• |en| is the mean error;
• and {en} is a sample of echo signal.

A robust echo canceller comprising:

• an adaptive filter for outputting an error signal in response to a detected echo signal;
• and
• means for supplying adaptive filter coefficients to said filter, wherein said filter coefficients are given by the formula:
• hn+1=hnμGnXnRxx−1(n) [φ(|en|)⊙ sign ([e]en)],wherein hn is the estimated echo path;
• μ is the overall step size parameter;
• Gn is the step-size matrix;
• Xn is the excitation matrix;
• Rxx−1 is the correlation matrix;
• |en| is the mean error;
• ⊙ denotes elementwise multiplications;
• and en is a residual echo vector.

A robust adaptive filter comprising:

• an adaptive filter utilizing a fast converging adaptive algorithm;
• means for modifying said algorithm by the application thereto of an adaptive scaled non-linearity;
• and
• a double talk detector connected to said adaptive filter for disabling said adaptive filter in response to the detection of double talk on a telephone circuit, said double talk detector also connected to said modifying means for controlling adaptation of said adaptive scaled non-linearity so as to reduce the impact of double talk on said filter by reducing divergence in a period of undetected double talk;
• wherein the fast converging algorithm is PNLMS++.

A robust adaptive filter comprising:

• an adaptive filter utilizing a fast converging adaptive algorithm;
• means for modifying said algorithm by the application thereto of an adaptive scaled non-linearity;
• and
• a double talk detector connected to said adaptive filter for disabling said adaptive filter in response to the detection of double talk on a telephone circuit, said double talk detector also connected to said modifying means for controlling adaptation of said adaptive scaled non-linearity so as to reduce the impact of double talk on said filter by reducing divergence in a period of undetected double talk;
• wherein the fast converging algorithm is PAPA.