Demodulator and communication apparatus

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 first and second differential demodulation signals based on the local oscillation signal synchronized by said frequency synchronization section and the modulation signal transmitted from the modulator;
• a first direct current correction section adapted to detect a first direct current voltage from the first demodulation signal produced by said demodulation signal production section and correct the first direct current voltage so that the first direct current voltage becomes equal to a first reference voltage set in advance;
• and
• a second direct current correction section adapted to detect a second direct current voltage from the second demodulation signal produced by said demodulation signal production section and correct the second direct current voltage so that the second direct current voltage becomes equal to a second reference voltage set in advance.

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 first and second differential demodulation signals based on the local oscillation signal synchronized by said frequency synchronization section and the modulation signal transmitted from the modulator;
• and
• a direct current correction section adapted to detect a first direct current voltage of the demodulation signal from the first demodulation signal produced by said demodulation signal production section and detect a second direct current voltage of the demodulation signal from the second demodulation signal and then correct at least one of the first direct current voltage and the second direct current voltage so that a potential difference between the first direct current voltage and the second direct current voltage becomes minimum.

A communication apparatus, comprising:

• a modulator adapted to modulate a modulation object signal with a first local oscillation signal to produce a modulation signal and transmit the produced modulation signal;
• a frequency synchronization section adapted to synchronize a frequency of a second local oscillation signal to be produced on the demodulator side with a local oscillation frequency of the modulation signal transmitted from said modulator;
• a demodulation signal production section adapted to produce a demodulation signal based on the second local oscillation signal synchronized by said frequency synchronization section and the modulation signal transmitted from said modulator;
• and
• a demodulator having 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.

A demodulator, comprising:

• frequency synchronization means for synchronizing 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;
• demodulation signal production means for producing a demodulation signal based on the local oscillation signal synchronized by said frequency synchronization means and the modulation signal transmitted from the modulator;
• and
• direct current correction means for detecting a direct current voltage of the demodulation signal from the demodulation signal produced by said demodulation signal production means and correcting the direct current voltage of the demodulation signal so that the direct current voltage becomes equal to a reference voltage set in advance.

A demodulator, comprising:

• frequency synchronization means for synchronizing 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;
• demodulation signal production means for producing first and second differential demodulation signals based on the local oscillation signal synchronized by said frequency synchronization means and the modulation signal transmitted from the modulator;
• first direct current correction means for detecting a first direct current voltage from the first demodulation signal produced by said demodulation signal production means and correcting the first direct current voltage so that the first direct current voltage becomes equal to a first reference voltage set in advance;
• and
• second direct current correction means for detecting a second direct current voltage from the second demodulation signal produced by said demodulation signal production means and correcting the second direct current voltage so that the second direct current voltage becomes equal to a second reference voltage set in advance.

A demodulator, comprising:

• frequency synchronization means for synchronizing 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;
• demodulation signal production means for producing first and second differential demodulation signals based on the local oscillation signal synchronized by said frequency synchronization means and the modulation signal transmitted from the modulator;
• and
• direct current correction means for detecting a first direct current voltage of the demodulation signal from the first demodulation signal produced by said demodulation signal production means and detecting a second direct current voltage of the demodulation signal from the second demodulation signal and then correcting at least one of the first direct current voltage and the second direct current voltage so that a potential difference between the first direct current voltage and the second direct current voltage becomes minimum.