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:
Sep. 05, 1989
Filed:
Aug. 10, 1987
Takanori Miyamoto, Fuchuu, JP;
Sumie Nakabayashi, Yokohama, JP;
Yoshiro Suzuki, Tama, JP;
Kazuhiro Kondo, Kokubunji, JP;
Shinichi Niina, Tokorozawa, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi VLSI Engineering Corporation, Tokyo, JP;
Abstract
An echo suppressor for a communication system wherein a signal sent to a transmitting line is returned to a receiving line with some delay. The suppressor comprises an attenuator for attenuating the amplitude of a received speech signal. The transmitting speech signal amplitude level is compared to the amplitude of a receiving speech signal, and according to the result obtained, a signal for controlling the signal attenuation of the attenuator is generated. The delay time, until the attenuation control signal operates on the attenuator according to a change in the amplitude level of the receiving speech signal, is controlled. The controlled delay time is normally held at a predetermined maximum value, and is minimized when a change in amplitude of the receiving speech signal indicates a beginning of speech. Thus, an echo of the speech uttered by a near end user can be suppressed without impairing a beginning of the speech signal uttered by a far end user.