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:
Dec. 26, 1995
Filed:
Dec. 15, 1993
Abstract
A sensor circuit for telephone line includes a line current detecting circuit (52, 54) which generates a detection signal in response to a line current flowing in a telephone line (20, 22). The detection signal is applied to a first amplifier (56), and the detection signal as amplified is not only further amplified by a second amplifier (57) but also applied to a tone deriving circuit (60) and a CI detecting circuit (61) via a coupling capacitor (59). The detection signal as amplified twice is applied to a comparing circuit (58) which compares the detection signal from the second amplifier with a first reference voltage (V1) and a second reference voltage (V2), so that a line current supervisory signal is outputted from the comparing circuit. The tone deriving circuit includes a band-pass filter and derives a tone signal from the detection signal from the first amplifier. The CI detecting circuit detects a CI (calling tone) on the basis of the detection signal from the first amplifier.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile