Method and circuit arrangement for detecting speech in a telepho

Details Method and circuit arrangement for detecting speech in a telepho Method and circuit arrangement for detecting speech in a telepho

1996-10-02

1998-10-06

Hunter, Daniel S.

Telephonic communications

Subscriber line or transmission line interface

Network interface device

704228, 379406, 379444, 381 66, H04M 100, H04B 320

Patent

active

058189289

ABSTRACT:
In communication networks with transmission devices using analog circuitry, because of unadapted 4-wire/2-wire junctions, some of the speech of a local speaker is reflected back to the local speaker as a line echo. This line echo is neutralized by echo compensators. However, updating of the filter coefficients of the echo compensators cannot be allowed to occur unless speech of the far-end speaker is absent. Thus, recalculation of the filter coefficients must be precluded at other times. Various possibilities for detecting the speech of a local speaker are well known. According to the invention, detection of the speech of a far-end speaker is fed back to obtain an attenuation measurement of the transmission path; this received speech simulates a reduction in attenuation. From the difference between the long-time average (Aa(k+1)) and the short-time average (A(k+1)) of the attenuation, it is learned very quickly, by comparison with a threshold (THRe), whether speech is present or not. The method is also applicable in order to discontinue automatic voice output on the local end by means of duplex voice communication.

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"Signalverarbeitungsverfahren Zur Verbesserung Der Sprachkommunikation Uber Freisprecheinrichtungen", R. Wehrmann et al, 48th Year, Oct. 1994, pp. 27-28.
"Kombination Von Gerauschreduktion Und Echokompensation Beim Freisprechen", T. Huhn et al, Communications Technology and Electronics, Berlin 43 (1993), pp. 274-280.

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