Adaptive echo cancellation device in a voice communication system

A device for adaptive echo cancellation in a voice communication system comprising:

• a circuit for transmitting a reference signal x over said communication system and receiving a primary signal d from said voice communication system, the primary signal including an echo signal from the voice communication system in response to the transmission of the reference signal x;
• an adaptive filter for removing any echo signal sent back by said voice communication system in answer to said reference signal and a normalization factor controlling unit for determining the value at time n of each coefficient of said adaptive filter based upon the value of the same coefficient at time n−1 modified by a normalization factor A(n) depending on the energy of said reference signal;
• the normalization factor controlling unit having a means for selecting said normalization factor as being the maximum value between a first value representing the energy of said reference signal at time n and a second value depending on a value of said normalization factor previously stored during a preceding predetermined interval time multiplied by an attenuation factor.

A method for adaptive echo cancellation in a communication system comprising the steps of:

• transmitting a reference signal x to the system;
• receiving a primary signal d from the system, the primary signal including an echo signal from the communication system in response to the transmission of the reference signal x;
• removing the echo signal from the primary signal d using an adaptive filter having a plurality of coefficients the value of which at each time n being computed from the value of the same coefficient at time n−1 modified by a normalization factor depending upon the energy of said reference signal d in that said normalization factor is the maximum value between a first value representing the energy of said reference signal at time n and a second value depending on a value of said normalization factor previously stored during a preceding predetermined interval time multiplied by an attenuation factor less than 1.