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:
May. 13, 1980
Filed:
Jun. 28, 1978
Applicant:
Inventors:
Takeo Fukuda, Yokohama, JP;
Hideaki Murayama, Yokohama, JP;
Assignee:
Tokyo Shibaura Denki Kabushiki Kaisha, Kawasaki, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
179 / ; 179 / ;
Abstract
This digital telephone conference system provides improved cancellation of reflective signals which cause echo-singing problems, such as caused by hydrid mismatches, for any number of telephone sets. Each telephone set is sequentially sampled for time sharing, and alternate samples are given opposite polarity signs before being summed, thereby making approximately half of the signals of opposite phase, for any number of telephone sets, for effective cancellation. Also, each member of the conference receives a sum signal of all telephone sets except his own.