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:
Jul. 26, 2016
Filed:
Oct. 13, 2014
Fujitsu Limited, Kawasaki-shi, Kanagawa, JP;
FUJITSU LIMITED, Kawasaki, JP;
Abstract
A frequency offset estimation circuit estimates a frequency offset that indicates a difference between a carrier frequency of a received optical signal and a frequency of a local oscillation light used to recover a transmission signal from the received optical signal. The frequency offset estimation circuit includes: a phase difference detector configured to detect a phase difference due to the frequency offset between a first symbol and a second symbol that is transmitted after the first symbol by a specified symbol interval based on a phase of the first symbol and a phase of the second symbol; an estimator configured to estimate the frequency offset based on the phase difference detected by the phase difference detector; and a symbol interval controller configured to specify the symbol interval based on the frequency offset estimated by the estimator.