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. 24, 2012
Filed:
Feb. 03, 2009
Huijian Zhang, Beijing, CN;
Lei LI, Beijing, CN;
Zhenning Tao, Beijing, CN;
Hisao Nakashima, Kawasaki, JP;
Huijian Zhang, Beijing, CN;
Lei Li, Beijing, CN;
Zhenning Tao, Beijing, CN;
Hisao Nakashima, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
The present invention discloses a frequency offset detecting apparatus and method for use in a digital coherent optical receiver. The digital coherent optical receiver comprises: a front-end processing section for generating a digital baseband electric signal; an equalizer for performing equalized filtering on the digital baseband electric signal; and the frequency offset detecting apparatus for detecting frequency offset contained in the digital baseband electric signal or frequency offset contained in a signal outputted by the equalizer; wherein the frequency offset detecting apparatus comprises an argument difference obtaining unit, a first subtracter, a second subtracter, a quantizer and an averager, of which the argument difference obtaining unit obtains an argument difference of adjacent symbols in a signal inputted therein; the first subtracter subtracts an output of the averager from the argument difference obtained by the argument difference obtaining unit; the quantizer performs uniform quantization with predetermined intervals on an output of the first subtracter; the second subtracter subtracts an output of the quantizer from the argument difference obtained by the argument difference obtaining unit; and the averager averages an output of the second subtracter.