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:
Nov. 13, 2007
Filed:
Jul. 15, 2004
Jin Soo Han, Daejeon, KR;
Youn Seon Jang, Daejeon, KR;
Hyun Jae Lee, Daejeon, KR;
Abstract
The present invention relates to an apparatus and method for performing optical Differential Phase Shift Keying (DPSK) modulation, which transmits a phase difference between adjacent bits as information. The electrically band-limited optical DPSK modulating apparatus includes a light source, a Non-Return-to-Zero (NRZ) signal generator, a pre-coder, an electrical low pass filter, and a phase modulator. The NRZ signal generator generates a NRZ signal. The pre-coder codes the NRZ signal generated by the NRZ signal generator into a differential signal. The low pass 'filter electrically limits a bandwidth of the differential signal obtained through the pre-coder. The phase modulator modulates an optical signal input from the light source into a DPSK signal using the differential signal having the bandwidth electrically limited by the low pass filter.