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. 03, 1985
Filed:
Aug. 22, 1983
Stanley D Rosenbaum, Ottawa, CA;
Zdenek J Holy, Nepean, CA;
Northern Telecom Limited, Montreal, CA;
Abstract
A supervision filtering function is included in a line circuit wherein tip and ring voltage amplifiers supply energizing current to a two wire communication line via tip and ring primary windings of a transformer and tip and ring feed resistors. The tip and ring amplifiers operate in response to a control circuit which is differentially responsive to resistively coupled voltage signals corresponding to current flows in the tip and ring feed resistors, and which is also differentially responsive to a.c. signals from a secondary winding of the transformer being coupled via a resistive capacitive network to an amplifier in the control circuit. An output of the amplifier provides a supervisory signal. A feed switch is operable by a ring signal to conduct ringing currents to the communication line via the tip and ring feed resistors to the exclusion of the tip and ring primary windings. A control switch is also operated at the same time by the ring signal to open circuit the secondary winding of the transformer such that a resistive capacitive network causes the amplifier to function as a low pass filter to reduce a.c. signal components in the supervisory signal.