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:
Feb. 18, 1986
Filed:
Mar. 12, 1984
Stanley D Rosenbaum, Ottawa, CA;
Calvin Plett, Ottawa, CA;
Northern Telecom Limited, Montreal, CA;
Abstract
A typical active impedance line feed circuit includes tip and ring amplifiers being controlled to exhibit a.c. impedance and d.c. resistance characteristics for the purpose of supplying energizing current for tip and ring leads of a two wire communication line. Protection from excessive heat generation in an instant of a ground fault on the communication line is provided by a d.c. amplifier having an input resistively connected to the tip and ring leads and an output connected via a resistive unidirectional current path to an input of the ring amplifier. A ground fault occurrence causes the resistive unidirectional current path to become conductive and reduces the current flow in the ring lead by causing the output voltage of the ring amplifier to vary in the direction of ground potential. The output of the d.c. amplifier is also useful for improving circuit tolerance of longitudinal interference.