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:
Jun. 18, 1996
Filed:
Sep. 28, 1994
Ian A Schorr, Chicago, IL (US);
AT&T Corp., Murray Hill, NJ (US);
Abstract
A circuit and method minimizes undesired noise signals associated with the battery utilized in a telephone battery feed circuit. In one embodiment, the noise voltage is amplified and inverted in phase and added back to a location on the ring line in order to provide substantial cancellation of the original noise voltage which would have appeared at the same location. In another embodiment, the noise voltage coupled to the ring line is reproduced as a replica signal. The replica signal is added in series with the tip line so as to provide equal phase and magnitude relationships relative to earth ground, thereby effectively canceling the noise current which would have flowed from the original noise source.