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:
May. 01, 2012
Filed:
Jul. 19, 2005
Tetsuya Kawanishi, Koganei, JP;
Masayuki Izutsu, Koganei, JP;
Tetsuya Kawanishi, Koganei, JP;
Masayuki Izutsu, Koganei, JP;
Abstract
It is an object of the present invention to provide an FSK demodulator which can be used in the optical information and telecommunications and the like, and which can appropriately demodulate an FSK signal by compensating a delay of an optical FSK modulated signal due to dispersion and the like of an optical fiber. The above-mentioned problem is solved by a frequency shift keying (FSK) demodulator () composed of a branching filter () for branching an optical signal according to wavelengths thereof; a delay adjusting apparatus () for adjusting a delay time of two lights branched by the branching filter; a first photodetector () for detecting one optical signal branched by the branching filter; a second photodetector () for detecting a remaining optical signal branched by the branching filter; and a means () for calculating a difference between an output signal of the first photodetector and an output signal of the second photodetector.