Echo Cancellation in Speech and Data Transmission

This tutorial paper reviews echo cancellation techniques as applied to both voice and data transmission applications. The echo control problem in telephone voice transmission is described, and the several measures taken to counteract echo are outlined. The problem of full-duplex data transmission over two-wire lines is described, with application to both digital subscriber loop and voiceband data transmission. The unique characteristics of each of these applications, more advanced methods recently proposed, and approaches to implementation are described.