Patent ID: 8310303

Claim:
A demodulator, comprising: a frequency synchronization section adapted to synchronize a frequency of a local oscillation signal to be produced on the demodulator side with a local oscillation frequency of a modulation signal transmitting from a modulator side; a demodulation signal production section adapted to produce a demodulation signal based on the local oscillation signal synchronized by said frequency synchronization section and the modulation signal transmitted from the modulator; a direct current correction section adapted to detect a direct current voltage of the demodulation signal from the demodulation signal produced by said demodulation signal production section and correct the direct current voltage of the demodulation signal so that the direct current voltage becomes equal to a reference voltage set in advance; and a phase correction section adapted to synchronize a phase of the local oscillation signal and a phase of the modulation signal with each other based on the direct current voltage of the demodulation signal detected by said direct current correction section.