| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a loop filter for an optical digital coherent receiver that can maintain reception quality even if more noise is superimposed on a received signal. <P>SOLUTION: The loop filter includes an amplitude adjustment control section for adjusting the amplitude of a phase rotation vector fed back from a phase rotation vector storage section. The amplitude adjustment control section determines whether or not the amplitude of the phase rotation vector fed back is within a constant range, and multiplies a feedback signal resulting from the multiplication of the phase rotation vector by a predetermined coefficient by a coefficient depending on the determination result to adjust the amplitude of the phase rotation vector. <P>COPYRIGHT: (C)2012,JPO&INPIT |
