Patent ID: 8744278

Claim:
A method for electric power supply control to control a supply state of electric power to an optical receiver, the optical receiver receiving signal light propagated in an optical fiber transmission line, converting the signal light into a digital electrical signal, and processing the obtained reception signal, to thereby reproduce data, when a digital signal processing is performed in the optical receiver, the method comprising: calculating a variable parameter used in waveform equalization of a reception signal, based on a state of the optical fiber transmission line; determining a variable parameter among calculated variable parameters, for which an absolute value is less than a previously determined threshold; and generating, for a circuit that performs waveform equalization of the reception signal, an electric power control signal for stopping electric power supply to a circuit part that corresponds to the determined variable parameter, wherein the performing of the waveform equalization is performed by a waveform equalizing circuit having a first filter and a second filter that are connected in series, and wherein the calculating calculates for each component of the reception signal, before starting a signal light operation, at least one variable parameter used in the first filter, corresponding to a dispersion compensation amount that has been determined in accordance with dispersion characteristics of the optical fiber transmission line, and after starting the signal light operation, the calculating monitors a waveform of the reception signal that has been waveform equalized by the waveform equalization circuit, and adaptively recalculates for each component of the reception signal, at least one variable parameter used in the second filter, so that the monitored waveform approaches an ideal waveform, and wherein, in response to an insufficiency of the number of the variable parameters used in the second filter for the waveform to approach the ideal waveform under the adaptive recalculation, the calculating recalculates the variable parameter used in the first filter so that the insufficiency is covered by additionally using the variable parameter used in the first filter.