Echo control in telecommunications

Shoji Makino, Shoji Shimada

研究成果査読

5 被引用数 (Scopus)

抄録

This paper reviews echo control techniques for telecommunications, emphasizing the principles and applications of both circuit and acoustic echo cancellers. First, echo generating mechanisms and echo problems are described for circuit and acoustic echoes. Circuit echo is caused by impedance mismatching in a hybrid coil. Acoustic echo is caused by acoustic coupling between loudspeakers and microphones in a room. The echo problem is severe when the round-trip propagation delay is long. In this case, the echo must be removed. Next, the basic principle of the echo canceller, adaptive filter structure and adaptive algorithm are discussed. Emphasis is focused on the construction and operation of an adaptive transversal filter using the NLMS (Normalized Least Mean Square) algorithm, which is the most popular for the echo canceller. Then, applications of circuit and acoustic echo cancellers are described. Circuit echo cancellers have been well studied and implemented in LSIs for many applications. Although acoustic echo cancellers have been introduced into audio teleconference systems, they still have some problems which must be solved. Therefore, they are now being studied intensely. Finally, this paper mentions the problems of echo cancellers and the direction of future work on them. The main targets for acoustic echo cancellers are improving the convergence speed, reducing the amount of hardware and bettering the double-talk control technique.

本文言語English
ページ(範囲)309-316
ページ数8
ジャーナルJournal of the Acoustical Society of Japan (E)
11
6
DOI
出版ステータスPublished - 1990
外部発表はい

ASJC Scopus subject areas

  • 音響学および超音波学

フィンガープリント

「Echo control in telecommunications」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル