| 摘要 |
PURPOSE:To simplify the constitution, by providing a means for modulating a subcarrier wave with communication signal and a means for designating a part of a transmission signal as a local oscillation signal for frequency modulation in providing a mutual communication line for ordering in unidirectional radio transmission. CONSTITUTION:In a station 1, a signal 4 for communication is modulated at a submodulator 5, synthesized at a synthesizer 6 with a television signal 3, modulated at a main modulator 7 and transmitted from an antenna 10. In a station 2, a signal 17 for communication is modulated at a submodulator 18, modulated at a submodulator 18, modulated at a main modulator 19 and transmitted from an antenna 22. In the station 1, the output of the main modulator 7 is used, a reception signal is frequency-converted into an intermediate frequency, demodulated 13, picked up for a carrier wave signal only of the submodulator 18 at a band pass filter 14 and demodulated 15. In the station 2, the reception signal is frequency-converted into an intermediate frequency by using the output of the main modulator 19, demodulated 25, and a television signal is branched at a signal distributor 26 and given to a low-pass filter 27. The communication signal is demodulated 30 after a carrier wave signal of the demodulator 5 is picked up at a band pass filter 29 and demodulated 30. |
