| 摘要 |
PURPOSE:To give a specific program to listners, by transmitting the specific frequency in the program audio signal band in the form of control signal of time series coding ahead the program, detecting this control signal at the reception side and controlling the reception system with the detected signal. CONSTITUTION:In broadcasting normal program with an audio equipment 1, the output from the audio braodcast unit 2 via a program signal cut-off switch 4 and it is transmitted from an antenna 3. Further, in case of emergency broadcast, the switch 4 is operated to interrupt the program broadcast, and the control signal insertion switch 5 is connected at the same time, prediction control signal is generated from the control signal generator 6 and it is broadcast from the broadcast unit 2 ahead the program. In this case, the control signal in series coding is detected at the control signal detection section 13 of the receiver in waiting state, an alarm device 17 is operated to produce alarm, the control relay 15 and the audio amplifier power switch 14 are operated, allowing listeners for the emergent broadcast. |
