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:
Jan. 25, 1977
Filed:
Mar. 20, 1975
Paul Abramson, Raleigh, NC (US);
Ulrich Appel, Munich, DT;
International Business Machines Corporation, Armonk, NY (US);
Abstract
A connection system for varied distance digital communication capable of handling telephone signals utilizes Voice Activity Compression (VAC) to effectively share a given number of digital transmission channels among a greater number of virtual telephone connections. The telephone signals are delta-modulated and demodulated in system connection stations. The VAC processing circuits with a small increment of decision logic provide echo suppression. Echo suppression is thereby rendered as a 'value-added' service at a relatively small increment of station cost over the cost of VAC processing. Echo interference with original telephone signal activity in the send channels is reduced by digital control of gain in the demodulation stage. The system also provides connections without VAC handling subject to echo control.