| 摘要 |
PROBLEM TO BE SOLVED: To provide a demodulator which is immune to disturbance and which has fixed synchronizing characteristics in spite of a frequency difference between the carrier frequency of an input signal and an internal local oscillation(LO) frequency. SOLUTION: Concerning the demodulator provided with a carrier wave reproducing circuit 10, the carrier wave reproducing circuit 14 is provided with an infinite phase shifter 14 and a phase difference detecting circuit 15, low-pass filter(LPF) 16, where adder 20 and NCO 21 are connected to this infinite phase shifter 14 so as to form a PLL. Further, the carrier wave reproducing circuit 10 is provided with a replace circuit 17 for executing processing for making the value of the LPF close to a central value after the synchronism establishment of a carrier wave, sweeper 18 and adder 19 for adding the output of this sweeper 18 and the output of the replace circuit 17 and outputting the result to the adder 20. |
