| 摘要 |
PURPOSE:To make a receiving local oscillator unnecessary when the output of a sending local oscillator is small, and to improve S/N, by cutting off the feed of a power of a transmitter oscillator to an opposite station in the line between horizontal synchronizing pulses during the vertical blanking period of a picture signal, and adding to the mixer at a receiving side. CONSTITUTION:An A station and a B station having sending and receiving devices 6, 9 are provided in the two-way wireless communication system of an FM system. A synchronizing signal extracting circuit 29 that inputs a picture signal, timing adjusting circuit 30, mixer 22, speed changing circuit 26 etc. are provided to the A station. A synchronizing signal extracting circuit 29-1, line reproducing circuit 14, speed changing circuit 16 etc. are provided in the B station. The feed of power of transmitter local oscillator to a receiving station is cut off in the line between horizontal synchronizing pulses during the vertical blanking period of the picture signal, and added to the mixer at a receiving side. The opposite station corresponding to the line applies FM modulation to the frequency of transmitter local oscillator by a digital signal to output the modulated carrier wave, and adds the output of the transmitter oscillator to the mixer at a receiving side in other time period. |
