| 摘要 |
PURPOSE:To reduce the phase jitter of a transmission output frequency by adopting the constitution that an IF signal and a local oscillation signal are used to extract a transmission video carrier. CONSTITUTION:Part of an IF signal 2 is branched by a coupler 11, supplied to a BPF-1 13, from which only a video carrier is extracted and supplied to a limiter 13 so as to suppress the amplitude modulation component and to recover the video carrier. On the other hand, part of the output of a local oscillation V/TCXO of a transmission section is extracted, the video carrier and the part of output are mixed by a mixer 14, the result is fed to a BPF-2 15, from which the video carrier of transmission frequency is obtained. On the other hand, the output of a highly stable crystal oscillator 8 is inputted to a frequency correcting device 7 as a reference signal, the video carrier obtained at the output of the BPF-2 15 is subject to phase detection based on the reference signal in the frequency correction device 7, and the detection output is used as a control voltage signal 9 to control the local oscillation V/TCXO.
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