Patent ID: 6163609
Filing Date: 2000-12-19
Classification: H04B

Abstract:
An echo cancelling system for removing the echo of a first signal from a second signal, said system havinga first input for inputting the first signal,a second input for inputting the second signalan output for outputting a processed signal;a first adaptive filter for producing a first echo estimate, said first adaptive filter having a first functional parameter and being arranged to produce said first echo estimate from a signal found at the first input substantially on the basis of said first functional parameter;a first subtracting element for subtracting the first echo estimate from a signal found at the second input to produce a first residual signal;a second adaptive filter for producing a second echo estimate, said second adaptive filter having a second functional parameter and being arranged to produce said second echo estimate from a signal found at said first input substantially on the basis of said second functional parameter;a second subtracting element for subtracting the second echo estimate from a signal found at the second input to produce a second residual signal;and which echo cancelling system is arranged to remove at least part of the echo of the first signal from the signal found at the second input and produces at the output a corresponding processed signal in which at least part of the echo of the first signal has been removed, and further comprises:a comparison element to compare at least the first residual signal and the second residual signal,and is arranged to choose the functional parameter used in the generation of the processed signal found at the output from the first and second functional parameters on the basis of the output signal of said comparison element,a first frequency band dividing element which is arranged to divide the first residual signal into at least two frequency bands, anda second frequency band dividing element which is arranged to divide the second residual signal into at least two frequency bands, andsaid comparison element is arranged to compare the first and second residual signals by comparing said at least two frequency bands of the first residual signal to the corresponding said at least two frequency bands of the second residual signal.