| 摘要 |
PURPOSE:To restore a switch into on-state when a received radio wave is reduced, the switch is turned off and a radio wave is recovered within a prescribed time by providing a timer circuit and a switch to a selective call selection of a disaster preventing radio equipment. CONSTITUTION:When a selective call signal from an antenna 1 is confirmed to be coincident with a prescribed signal in a local disaster preventing receiver, a switch circuit 6 is turned on and a voice signal received afterward is outputted from a speaker 5. When the level of a received input electric field is lowered in this state and the circuit 6 is turned off, the timer circuit 8 starts time count. When the reception input electric field is restored more than a prescribed level during the time count of the circuit 8, a switch 9 is activated to operate a detector 7 thereby restoring the circuit 6 to the ON-state. Thus, even when momentary interruption takes place due to the effect of a shield, the voice signal is received succeedingly after the effect of the shield is lost. |
