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:
Oct. 21, 1997
Filed:
Nov. 09, 1995
Shigefumi Masuda, Kawasaki, JP;
Fujitsu Limited, Kanagawa, JP;
Abstract
In a hybrid SCM optical transmission apparatus, and particularly in a hybrid SCM optical transmission apparatus which performs transmission by modulating laser light by a hybrid signal formed by frequency multiplexing an analog-modulated signal with a digitally modulated signal to form a hybrid AM-QAM signal, for the purpose of both effective utilization of transmission bandwidth and reduction of clipping deterioration, a signal limiting section which applies limiting to the analog-modulated signal is provided, frequency-division multiplexing being done of analog-modulated signal output from this signal limiting section and a digitally modulated signal. In place of this signal limiting section, a signal limiting section which applies limiting to the hybrid signal, or a delay circuit which delays the hybrid signal by a prescribed amount of time and a clipping compensation section which generates a clipping compensation signal which inhibits the clipping of laser light output by means of a predicted clipping strength which is detected from the hybrid signal during the delay period are used. These are appropriately feedback controlled, in accordance with monitoring of the laser light output.