Echo Canceller With Analog Flat Delay
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
Echo signals occurring in a digital voice transmission network, wherein the voice path includes two wire sections and four wire sections, are conventionally cancelled through the use of an echo canceller made of a digital filter generating an echo replica to be subtracted from the echo path. The echo replica should, in theory, be made as close as possible to the echo path impulse response. This could be achieved by putting in the echo canceller a flat delay line ahead of the filter delay line. This flat delay could be rather important, for instance, in networks wherein satellites are involved. Digital generation through the use of random-access memory positions would be rather bulky and expensive.