Digital signal processing circuit, method, receiver, and communication system

Abstract

A detector is configured to coherently receive a polarization-multiplexed optical signal transmitted from a transmitter via a transmission line. A digital signal processing circuit is configured to perform equalization signal processing on the reception signal coherently received. A carrier phase compensation filter is configured to compensate for a carrier phase in the reception signal. A 4×2 WL filter is disposed after the carrier phase compensation filter and configured to compensate for distortion included in the polarization-multiplexed optical signal. A filter coefficient updating unit is configured to update a filter coefficient of the carrier phase compensation filter and a filter coefficient of the 4×2 WL filter by use of an output of the 4×2 WL filter.

Dependencies are inferred from the claim text.