| 摘要 |
PURPOSE:To attain stable operation even when degree of modulation of a trans mission video signal is large and to dispense with the adjustment in all television channels for a VHF band by using a narrow band limiter to suppress a video amplitude modulation component. CONSTITUTION:A transmission video signal of a VHF channel including an amplitude modulation component is inputted to a mixer 3. A BPF extracts a signal of 2.75MHz having a lowest frequency in those of an output signal of the mixer 3, a limiter 5 eliminates the amplitude modulation component, a waveform generator 6 converts the result into a 2.75MHz pulse and it is converted into a 25kHz pulse by a frequency divider 7. On the other hand, part of the output of a 6MHz oscillator 1 is subject to 1/240 frequency division by a frequency divider 8 to obtain a 25kHz pulse and the phase is compared with a phase of a 25kHz pulse received from the frequency divider 7 at a phase comparator 9. Its phase error voltage controls an output frequency of a sender use local oscillator in a transmitter of a TV repeater main body 100 via an LPF 10. |
