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:
Aug. 04, 1981
Filed:
Jun. 04, 1979
Robert C Stewart, Hinsdale, IL (US);
Tellabs, Inc., Lisle, IL (US);
Abstract
A residual echo suppressor for an echo canceller compares the levels of the uncancelled signal and the residual signal. If the level of the residual signal has a selected proportionality to the level of the uncancelled signal, it is assumed that the residual signal consists solely of echo and it is suppressed to zero. If the residual signal fails the proportionality test, which indicates that it may contain speech, it is transmitted in its entirety. To prevent sporadic transmissions of residual signal which fails the proportionality test, but which might not contain speech, a hysteresis circuit blocks transmission of the residual signal upon the same continuously failing the proportionality test for a selected time, at the end of which time the residual signal is assumed to contain speech and is transmitted.