| 摘要 |
PURPOSE:To attain communication without providing a transmission line exclusive for communication by transmitting a call signal subject to time division and multiplexing and a channel selection or other control signals after superimposing them on a blanking part of a television video signal. CONSTITUTION:An output signal of a telephone terminal equipment 11 is converted into a digital signal at a PCM modulating section 13 and a channel of time division multiplexing is designated by an exchange control section 15. Further, the signal is multiplexed by matching the timing to a horizontal scanning synchronizing blanking section of a transmitted TV signal at a transmission section 16. A signal multiplexed at the horizontal scanning blanking section is outputted to the exchange control section 15 at a receiving section 17 and a signal multiplexed at the vertical blanking period is outputted to a central control section 19 respectively. The signal inputted to an exchange control section 15 enters a prescribed path through a channel designated by the central control section 19, converted into an analog signal at a PCM demodulating section 14 and outputted to the telephone terminal equipment 11. |
