| 摘要 |
PURPOSE:To stabilize the warning function of the whole system by operating all equipments in response to an emergency warning signal clipped at a necessary signal level after detection, and preventing unnecessary driving by an emergency warning signal from a disturbing station. CONSTITUTION:The intermediate signal of a heterodyne receiver for medium wave radio broadcast reception is led from an input terminal to an envelope detector 2 to listen to the radio. Once an emergency warning broadcast starts, a circuit part for emergency broadcast reception is put in operation by the emergency warning signal and the detection output signal of the envelope detector 2 is supplied to an envelope detector 6 to supply a detection output signal containing a DC component to a clipper 7. After a level signal component exceeding the clipping level is removed, the resulting signal is supplied to a decoder 8 to control a power source driving circuit 9 by the necessary emergency warning signal. Consequently, the same emergency warning signal frequency component from a disturbing station is never obtained. |
