| 摘要 |
PURPOSE: To reduce circuit scale by attaining frequency synchronization and phase synchronization only with one complex multiplier and one digital control signal generator by enabling the demodulator to execute phase error pull-in operation while putting the oscillation frequency of the digital control signal generator at the time of frequency error pull-in end at a center. CONSTITUTION: A digital modulated intermediate frequency signal is converted into a first base band signal in an orthogonal phase detector 2 base on the output signal of a fixed oscillator 1. Then, it is converted into a second base band signal in a complex multiplier 6 based on the output signal of a digital control signal generator 14. A phase error detector 8 and a frequency error detector detect phase difference and frequency difference between the carrier wave of the first base band signal and the output signal of the digital control signal generator 14, respectively. A control circuit 10 performs switching between the frequency error signal and a zero signal, and the phase error signal and a zero signal to output them. An adder 13 adds the results to feed back them to the digital control signal generator 14. |
