The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 07, 1987
Filed:
May. 07, 1985
Jean Lassaux, Lannion, FR;
Christian Dagorn, Perros Guirec, FR;
Abstract
This arrangement is intended to control the operation of the coefficients adjusting circuit (12) of an echo canceller and of the operation of a center clipper (15) inserted in the send path (7) of a four-wire circuit at the output of the subtractor (13) of the echo canceller for suppressing there, when it is set to its active state, the signals whose amplitude is lower than or equal to a clipping threshold. The control arrangement operates on the basis of the signal in the receive path (2) of the four-wire circuit, the level N.sub.REC of this signal and the levels N.sub.AV and N.sub.AP of the signals before and after the subtractor (13). It comprises a controller (21) for comparing the level N.sub.AV to two fixed thresholds N.sub.AV0, N.sub.AV1 and for comparing the ratio N.sub.AP /N.sub.AV to a threshold a which is capable of varying as a function of N.sub.AV, the center clipper being only set to its active state when the level N.sub.AV is comprised between N.sub.AV0 and N.sub.AV1 and the ratio N.sub.AP /N.sub.AV is below a threshold a, the clipping threshold varying in accordance with an increasing function of the level N.sub.AV.