Patent ID: 7310425

Claim:
A method of adaptively filtering a signal transmitted over a channel, said signal containing an input signal and multiple echo responses, said multiple echo responses to be adaptively filtered, said method comprising the steps of: generating an estimate of an echo response corresponding to each of said multiple echo responses, wherein each of said estimates is generated via the equation: {circumflex over ( h )} ( m )= {circumflex over ( h )} ( m− 1)+(1−λ f ) S −1 ( m ) D H ( m ) e ( m ) where e ( m )= y ( m )− GD ( m ) {circumflex over ( h )} ( m− 1), and S ⁡ ( m ) = ⁢ ( 1 - λ f ) ⁢ ∑ p = 0 m ⁢ λ f m - p ⁢ D H ⁡ ( p ) ⁢ G ⁢ ⁢ D ⁡ ( p ) = ⁢ λ f ⁢ S ⁡ ( m - 1 ) + ( 1 - λ f ) ⁢ D H ⁡ ( m ) ⁢ G ⁢ ⁢ D ⁡ ( m ) : wherein ĥ =the frequency domain estimate of the impulse response; m=a block time index; λf=an experimental forgetting factor in the frequency domain; D=a diagonal matrix whose elements are the discrete Fourier transform of the first column of the circulant matrix; H =conjugate transpose; e=frequency domain error signal; y=channel output signal; G=F −1 WF; F=the Fourier matrix; and W = [ 0 L × L O L × L 0 L × L I L × L ] ; generating a sum of said estimates; and generating an error signal representing the difference between said signal and said sum of said estimates; wherein said estimates are generated using a frequency domain recursive least squares algorithm.