| 摘要 |
PURPOSE:To absorb a drift and Doppler frequency fluctuation in a long period. CONSTITUTION:A frequency converter 1 converts a PSK modulation carrier signal Si passing an input band-pass filter 11 and an output signal S5 from a voltage controlled oscillator(VCO) 4 to an IF signal S1 by mixing. A demodulator 2 demodulates the IF signal S1, and outputs a demodulation signal So and a frequency error signal S2. A low-pass filter 3 eliminates an unrequired component included in the error frequency signal S2, and outputs a control signal S3 to absorb the drift in a long period. A multiplier 6 and a band-pass filter 7 multiply the IF signal S1, and the unrequired component is eliminated, and a carrier component S6 is extracted. A phase comparator 8 outputs a phase difference signal S7 by comparing the carrier component S6 with an output signal S9 from a VCO 10. A low-pass filter 9 eliminates the unrequired component, and outputs a control signal S8 to absorb the Doppler frequency fluctuation. An adder 5 supplies a control signal S5 on which the control signals S3 and S8 are superimposed to the VCO 4. |
