| 摘要 |
PURPOSE:To attain automatic control of a local oscillator frequency with a simpler constitution by implementing the frequency control of the local oscillator while comparing voltages for the local oscillator frequency and a modulated wave frequency. CONSTITUTION:A biphase PSK(phase shift keying) modulation wave is inputted to a frequency conversion circuit 10 and inputted to an automatic frequency controller 40 and the modulated wave inputted to the controller 40 is frequency voltage converted at an FVC(frequency voltage converter) 42, and its voltage is inputted to a subtractor 46. On the other hand, a single resulting from frequency voltage conversion 44 of a local oscillator being the output of a VCO 50 is inputted to the subtractor 46. The subtractor 46 subtracts the output of the FVC 42 and the output voltage of the FVC 44 and the difference voltage between output voltages of the two FVC 42 and 44 is outputted. The difference voltage outputted from the subtractor 46 is fed to the VCO 50 via a loop filter 48. The frequency of the local oscillator is changed in the VCO 50 in response to the inputted voltage. |
