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:
Aug. 26, 1997
Filed:
Sep. 12, 1995
Yuzo Yamamoto, Kawasaki, JP;
Fujitsu Limited, Kanagawa, JP;
Abstract
A circuit for issuing a loop detection signal in a subscriber circuit which sends information in the form of an AC signal to a subscriber while applying a bias voltage to the subscriber line by an on-hook transmission signal during idle intervals of a ringer output to the subscriber and, at the same time, varies the threshold value of loop detection at the loop detection circuit, wherein provision is made of a masking unit which controls whether to issue the loop detection signal SCN from the loop detection circuit without a mask or to mask that SCN according to the masking signal ms, an SCN supervisory unit which supervises the loop detection signal SCN and applies a masking signal ms masking the loop detection signal SCN appearing immediately after the restoration of the on-hook transmission signal as the erroneous detection signal to the masking unit; and a masking time setting unit which sets the time length of the masking signal ms and applies the reset signal rs for the masking signal to the SCN supervisory unit after an elapse of that time.