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:
Jan. 25, 1994
Filed:
Nov. 21, 1991
Applicant:
Inventors:
Assignee:
Fujitsu Limited, Kanagawa, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04J / ; H04J / ;
U.S. Cl.
CPC ...
370 16 ; 371-82 ; 34082501 ;
Abstract
A maintenance signal transmission system incorporates a transmitting station, a receiving station, a main line which connects the transmitting station and the receiving station, and a backup line which connects the transmitting station and the receiving station. The transmitting station at least includes a switch for selectively connecting to one of the main line and the backup line to transmit a main signal and a maintenance signal to the receiving station using the selected line. The receiving station at least includes an adder for adding maintenance signals which are received from both the main line and the backup line. The main and backup lines may or may not take mutually different routes.