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. 27, 1991
Filed:
Aug. 28, 1990
Jacques Abiven, Plouaret, FR;
Alain Rebours, Lannion, FR;
Abstract
A loop-back device is particularly designed to fit line terminals in half-duplex optical transmission systems thereby facilitating fault location in these transmission systems. An optical fiber coupler having a high crosstalk generates an echo in a reception channel of the terminal, from a test signal transmitted in a transmission channel of the terminal, to an optical transmission medium. Means are provided for cancelling transmission of the echo in the reception channel when the loop-back is de-activated, i.e. when a data signal is carried in the transmission medium, and for amplifying and regenerating said echo when the loop-back is activated, i.e. when said test signal is transmitted. A memory is used for delaying the echo and for transmitting it to a receiving circuit in the terminal during a signal reception period of the half-duplex transmission.