Patent ID: 9667350
Date: 2017-05-30
CPC Classifications: H04B,H04L

Claim:
1. An optical receiving device that receives an optical signal that has been modulated by means of phase modulation or quadrature amplitude modulation, converts the received optical signal into an electrical signal using coherent detection, and performs phase compensation on the converted received signal, comprising: a carrier phase estimation unit configured to estimate carrier phase errors in a received symbol string obtained from the received signal; a gain adjustment unit configured to perform gain adjustment on symbols input into the carrier phase adjustment unit; a phase cycle slip reduction unit configured to detect general noise that causes a phase cycle slip, and reduces the phase cycle slip; and a phase compensation circuit configured to compensate carrier phase errors contained in the received signal using an output from the carrier phase estimation unit wherein the phase cycle slip reduction unit includes: a delay difference value calculation circuit configured to receive a signal output from the carrier phase estimation unit, and configured to calculate a delay difference value; and a slip determination unit configured to evaluate an output from the delay difference value calculation circuit and then determines whether or not a phase cycle slip exists, and the phase compensation circuit includes: a circuit into which an output from the carrier phase estimation unit is supplied and so as to perform phase compensation; and a slip compensation unit configured to receive a determination signal showing that general noise has been detected so as to compensate a phase cycle slip.