| 摘要 |
PURPOSE:To transmit a digital signal without affecting the transmission of a picture signal, by transmitting various types of information as digital signals within a vertical flyback period of a picture in the direction opposite to the transmitting direction of the picture signal. CONSTITUTION:The vertical synchronizing signal of a picture signal is extracted through a synchronizing signal extracting circuit 30 at the receiving side of the picture signal and then transmitted to a velocity modulation circuit 32 via a delay circuit 31. Both digital signal DG and clock signal CLK are supplied to the circuit 32, and the signal DG is applied to a modulator 33 only within the flyback period of the picture signal. The modulated output is transmitted from an antenna 21 and received by an antenna 7 at the transmitting side of the picture signal. The received wave of the digital signal is sent to a BPF8 and then mixed by a mixer 9 with the modulated signal of the picture signal branched by a branching circuit 4, and is turned into an IF signal. This IF signal is demodulated by a demodulator 11 corresponding to the modulating system of the digital signal after applied with IF amplification 10. |
