| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a frame circuit which performs frame synchronization in an accurate time by shortening a detection time of FAS of an OTN frame described in ITU-T G.709 when a circuit which demodulates an optical DQPSK signal is initialized. <P>SOLUTION: A frame synchronizing circuit which is equipped with a transponder receiving optical DQPSK modulated frames, converting the optical signal thereof into an electric signal, and performing DQPSK demodulation and synchronizes the frames is equipped with a correcting circuit which corrects the signal input from the transponder, an alignment detection block which detects an FAS position pattern of the signal input from the transponder, and a synchronism protecting circuit which receives a signal from the alignment detection block and synchronizes the frames when the alignment detection block detects the FAS position pattern. <P>COPYRIGHT: (C)2009,JPO&INPIT |
