Echo control in VoIP
Keywords:Feedback control, Gateways (computer networks), Internet protocols, Microphones, Telecommunication systems, Echo canceller, Echo control, Voice over the Internet Protocol
AbstractThe challenges faced in echo control in voice over the Internet Protocol (VoIP) are discussed. There are primarily two classes of echo in telephone conversation. The first class is due to the use of a 2-to-4 wire conversion using hybrid circuits. Echo control of this class is achieved by a line echo canceller (LEC). The other class is due to the use of handsfree mechanisms where there is significant acoustical feedback coupling between the receiver speaker and the receiver microphone. Echo control of this class is achieved using an acoustic echo canceller (AEC). The design of double-talk detectors is a challenge for VoIP gateway design. Another challenge seen in deploying VoIP with voice gateways to interface with PSTN is that some PSTN local loops have strange characteristics. It is highly desirable to measure echo at the end user of an IP phone with multi-vendor networks. An important impairment, that is to be measured, is echo with its echo path loss and its associated round-trip delay.
How to Cite
Copyright on articles is held by the author(s). The corresponding author has the right to grant on behalf of all authors and does grant on behalf of all authors, a worldwide exclusive licence (or non-exclusive license for government employees) to the Publishers and its licensees in perpetuity, in all forms, formats and media (whether known now or created in the future)
i) to publish, reproduce, distribute, display and store the Contribution;
ii) to translate the Contribution into other languages, create adaptations, reprints, include within collections and create summaries, extracts and/or, abstracts of the Contribution;
iii) to exploit all subsidiary rights in the Contribution,
iv) to provide the inclusion of electronic links from the Contribution to third party material where-ever it may be located;
v) to licence any third party to do any or all of the above.