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:
Jul. 05, 1977
Filed:
Jun. 28, 1976
Applicant:
Inventor:
Richard Scott Hoppough, Greensboro, NC (US);
Assignee:
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
179 / ; 1791 / ; 324 51 ;
Abstract
A controlled-amplitude, alternating test signal at a central office is applied to a telephone subscriber's line. The nonlinear impedance vs. voltage characteristic of the subscriber's telephone in an off-hook state causes harmonics of the test signal to be generated. A harmonic so generated is detected at the central office, which indicates the presence of a receiver-off-hook telephone.