| 摘要 |
PURPOSE:To attain utilization for a transmitter of the microwave band, etc., by making it possible to stabilize a trasmission frequency with simple circuit constiution by providing a phase comparator for control over the oscillation frequency of a modulating oscillator. CONSTITUTION:The 2nd oscillator 10-2 generating fixed difference frequency fd is provided and its reference frequency output is supplied to one input of phase comparator 11. On the other hand, the 1st oscillator 10-1 generating local oscillation frequency f1 is also provided. Difference frequency fd=ft-f1 (provided that ft is a transmission frequency) is extracted by modulator 9 and amplified at 4-2 and its output is applied to the other input of comparator 11, which generates a comparison output according to a phase difference between both the inputs, thereby controlling the oscillation frequency of oscillator 2 directly. Namely, the oscillation frequency of oscillator 2 is controlled with a DC voltage obtained from comparator according to the fluctuations of frequency ft to obtain a center frequency, so that the stabilization of frequency ft will be secured. |
