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. 20, 1977
Filed:
Sep. 18, 1975
Applicant:
Inventor:
Eduard Zwack, Puchheim, DT;
Assignee:
Siemens Aktiengesellschaft, Munich, DT;
Primary Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
179 / ; 179 / ;
Abstract
A method for connecting subscribers to form a conference call in a time division multiplex (TDM) telecommunication switching system having a TDM ring-like circuit running from subscriber to subscriber is described. A subscriber speech word is added to a pulse code modulated (PCM) word transferred to the subscriber station, and the summation PCM word is both retransferred and stored in the subscriber station for a time-slot frame. The stored preceding PCM word is subtracted from the PCM word transferred to the subscriber station, and the differential PCM word forms an aural signal.