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. 09, 1997
Filed:
Feb. 10, 1994
Brian A Sutherland, Kanata, CA;
Stanley Daniel Rosenbaum, Nepean, CA;
Paul Fong-Yan Hung, Stittsville, CA;
Northern Telecom Limited, Montreal, CA;
Abstract
A telephone line interface circuit comprises a controlled voltage generator for selectively generating a ringing voltage waveform for a telephone line or a supply voltage for a drive circuit for the telephone line, and a switching circuit interconnecting an output of the controlled voltage generator, the drive circuit, and the telephone line accordingly. In order to avoid creating a potentially hazardous condition on the telephone line, an interlock is provided between enabling of the controlled voltage generator and switching of the switching circuit, and software and hardware monitoring functions monitor operation of the control software and the controlled voltage generator and disable the controlled voltage generator in response to fault conditions or unusual behavior.