| 摘要 |
PROBLEM TO BE SOLVED: To speedily detect whether a filter coefficient, as for adaptation, is correct or incorrect.SOLUTION: A receiving section of a light receiver has a signal processing section 106 which processes a reception signal polarization-multiplexed into a digital signal after the reception signal is polarization-separated. The signal processing section 106 comprises: an adaptive equalization circuit 202 which compensates for a reception signal by the control of a filter coefficient after the polarization separation; a first frequency offset estimating circuit 210 into which the previous reception signal of the adaptive equalization circuit 202 is branched and input and which estimates a frequency offset for each polarization; a second frequency offset estimating circuit 211 into which the subsequent reception signal of the adaptive equalization circuit 202 is branched and input and which estimates the frequency offset for each polarization; and a determining circuit 212 which determines whether the filter coefficient is correct or incorrect by the estimated-value difference acquired by comparing the estimated values of the frequency offsets estimated by the first and second frequency offset estimating circuits 210 and 211. When determining that the filter coefficient is incorrect, the determining circuit 212 outputs a trigger to the adaptive equalization circuit 202 in order to calculate a filter coefficient again. |
