Patent ID: 9496966
Filing Date: 2016-11-15
CPC Classification: H04B

Claim Text:
1. An optical communication receiving device that converts, to a digital signal, a signal in which signal light from an optical transmission path and local oscillation light are mixed, so as to perform digital signal processing, the optical communication receiving device comprising: a frequency offset compensator configured to calculate a frequency offset of the digital signal and to, based on the frequency offset, compensate for a phase of the digital signal; a carrier phase recoverer configured to calculate a carrier phase of the digital signal whose phase is compensated for in the frequency offset compensator; and a residual frequency offset detector configured to calculate an average of differences in a carrier phase of each of a plurality of symbols, and to output the average as a residual frequency offset, wherein the frequency offset compensator is configured to correct the frequency offset using the residual frequency offset output by the residual frequency offset detector, and wherein the residual frequency offset detector is configured to set a difference in the carrier phase to zero when an absolute value of the difference in the carrier phase exceeds a predetermined value.