Echo canceller design and implementation of a CCITT V32 modem: software solution

Author

Alvarez, A.M.

Author_Institution

NV Telindus, Leuven, Belgium

fYear

1989

Firstpage

1384

Abstract

The authors describe a software solution for echo cancellation in a full-duplex two-wire high-speed modem. A PLL (phase-lock loop) structure consisting of a second-order low-pass filter implemented in multiprecision arithmetic for both half- and full-duplex operation is used. Combined with the far-end echo canceller, it produces a very reliable alternative capable of tracking up to 10-Hz frequency offset affecting the first remote echo. The digital signal processing was obtained by using the ADSP 2100. Some tests have been made with two V32-based modems between Belgium and the United Kingdom, between Belgium and Sweden, and within Belgium. Some results are shown on the echo cancellation performance as well as the type of transmission lines and impairments affecting them

Keywords

computerised signal processing; digital filters; echo suppression; modems; standards; ADSP 2100; Belgium; CCITT V32 modem; PLL structure; Sweden; United Kingdom; V32-based modems; digital signal processing; echo cancellation; far-end echo canceller; full-duplex operation; full-duplex two-wire high-speed modem; half-duplex operation; impairments; multiprecision arithmetic; offset; performance; phase-lock loop; remote echo; second-order low-pass filter; software solution; transmission lines; within; Arithmetic; Baseband; Couplers; Echo cancellers; Frequency; Modems; Phase locked loops; Pulse modulation; Telephony; Transversal filters;

fLanguage

English

Publisher

ieee

Conference_Titel

Acoustics, Speech, and Signal Processing, 1989. ICASSP-89., 1989 International Conference on

Conference_Location

Glasgow

ISSN

1520-6149

Type

conf

DOI

10.1109/ICASSP.1989.266696

Filename

266696