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:
Mar. 16, 1999
Filed:
Oct. 17, 1997
Koichi Shiraki, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
The present invention provides a hands-free telephone wherein near-end caller voice detection information is provided with little error, and wherein electric power saving effects are improved, and also wherein the far-end caller does not receive an unnatural impression. An echo canceller comprises: level calculating unit 1, 2, and 3 for calculating the level of reception signals, input transmission signals, and residual signals; and adaptive filter 4 for inputting the reception signals and transmission input signals and outputting residual signals; echo cancellation amount calculation unit 5 for calculating the echo cancellation amount from the input transmission signal level and residual signal level; voice detection threshold value control unit 6 for controlling the voice detection threshold value according to the reception signal level and the echo cancellation amount; voice detection unit 7 for outputting a voice detection flag using the residual signal level and the voice detection threshold value; attenuator control unit 9 for controlling the suppression amount based on the reception signal level, and attenuator 10 for performing suppression according to the suppression amount.