| 摘要 |
PURPOSE:To give the normal signal only to a specific receiver, by superposing a disturbance signal on a TV signal. CONSTITUTION:A control signal (b) is superposed on a TV signal to discriminate the subscribers. The signal (b) is extracted from the TV signal through a separating circuit 14 and decoded by a matrix circuit 9. An oscillating circuit 22 oscillates the disturbing radio wave to a specific charged broadcast channel. A subscriber of the charged broadcast is discriminated by the output signal of the circuit 9. A control circuit 10 controls a switch 21 to put a disturbing ratio wave on an antenna cable led to a non-subscriber. This unables the non-subscriber to watch the charged broadcast. |
