| 摘要 |
PURPOSE:To narrow the band of the BPF of a master station by providing a VCO connected to a cable at a slave station, providing a phase comparator, a reference oscillator, an LPF and a regulator and constituting a PLL as a whole. CONSTITUTION:The output voltage of a regulator 32 of a master station 20 is supplied through a transmitting cable 26 to VCO22 of a slave station 21. In short, a PLL is constituted of the VCO22 of the slave station 21, a reference oscillator 20 of the master station 20, a phase comparator 29, an LPF 31 and a regulator 32. For this reason, when the voltage of a frequency control terminal 24 falls and a frequency f1 of the output carrier of the VCO22 is lower than a reference frequency f2, the voltage of a frequency control terminal 25 rises, it functions so as to raise the frequency f1 of the output carrier of the VCO22 and the frequency f1 is always locked to the frequency f2. Thus, the band of the BPF36 of the master station 20 can be made very smaller and the fluctuation of the frequency due to the temperature change, etc., of the VCO22 can be absorbed.
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