| 摘要 |
PURPOSE:To detect a channel, which is received by the receiver, and report it to the center, by mixing the channel discrimination signal of a frequency outside the audible band into the sound signal of each channel transmitted from the center and by transmitting them to the receiving side. CONSTITUTION:The sound signal is included in the video signal, and the channel discrimination signal is mixed in the sound signal with an ultrasonic wave, and they are transmitted from the center to the receiving side. When the video signal is input to converter 31 through branching equipment 30 in the receiving side, a channel selected by control box 12 is converted to a specific frequency to cause TV receiver 11 to receive the selected channel. When the selected channel is received, sound of the channel is emitted from the speaker, and this sound is picked up by microphone 32 to detect the channel discrimination signal in sound by channel discriminating circuit 33. The audient channel is discriminated and is sent from transmission circuit 34. |
