Method and apparatus for inhibiting echo in a channel of a communication system

DETAILED DESCRIPTION An object of this invention is to provide an improved method and apparatus for performing echo cancellation.
Another object of the invention is to provide a method and apparatus for performing echo cancellation while allowing reducing the amount of switched loss necessary to maintain an acceptable echo control.
As embodied and broadly described herein, the invention provides an echo canceller for reducing the magnitude of an echo occurring in a return channel of a communication device, said echo canceller including: first processing means for generating an echo estimate, said first processing means including a first input for receiving a signal that is a precursor of the echo in the return channel of the communication device; second processing means in operative relationship with said first processing means, said second processing means being responsive to said echo estimate for conditioning a signal input in the return channel of the communication device to generate an output signal in which echo is inhibited, the output signal being a residual echo signal; a signal attenuation device for receiving and attenuating either one of the residual echo signal and the signal that is a precursor of the echo in the return channel of the communication device, said signal attenuation device manifesting a variable signal attenuation rate.
For the purposes of this specification, the expression "switched loss device" designates a system designed to limit or attenuate a signal in a non-linear manner.
The switched loss device is not necessarily a component installed at a single location but it can be constituted by a distributed system including a series of components installed at various locations permitting to effect signal attenuation over one or more separate signals, namely the residual echo signal and the signal precursor of the echo signal.
In a most preferred embodiment of this invention, the switched loss device measures the power of the residual echo signal to determine the amount of attenuation to be effected by the signal attenuation device necessary to reduce the echo to acceptable levels