| 摘要 |
PROBLEM TO BE SOLVED: To recover a carrier with an accurate frequency. SOLUTION: This circuit is provided with a frequency conversion circuit 1 converting a frequency of a received RF signal into a frequency of an IF signal, a demodulation circuit 3 demodulating an output of the circuit 1 into a base band signal, a carrier recovery circuit 2 recovering a carrier, a voltage controlled oscillator(VCO) 4 oscillating a local oscillation signal, a variable frequency divider means 6 dividing a received signal variably, a reference signal generating means 7 generating a reference signal, a phase comparator means 9 comparing phases, and an output of the means 9 is used to control the oscillated frequency of the voltage controlled oscillator VCO 4 as a control voltage. In this case, the reference signal generating means 7 is made up of a variable reference oscillator 13 and frequency discrimination means 11, 12 discriminating the frequency of the carrier are provided and an output of the frequency discrimination means 11, 12 is used to control the carrier frequency to be constant. |
