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:
Oct. 02, 1979
Filed:
Dec. 19, 1977
Applicant:
Inventors:
Assignee:
Societe Lignes Telegraphiques et Telephoniques, Paris, FR;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
179 / ;
Abstract
An apparatus comprising a stopband filter, a linear amplifier, a limiter circuit, a narrow band filter and a threshold circuit, insensitive to voice signals. When signalling signals are emitted with two frequencies, the apparatus comprises two channels each of them being protected by an input reject filter against one of the signalling frequencies.