| 摘要 |
<p>PURPOSE:To prevent radio interference, by measuring a timewise shift between a receiving signal and a reference signal every time a receiver receives a signal from each transmitter and producing alarm when the shift exceeds a prescribed value. CONSTITUTION:Reset terminals 3a, 3b of a timer 3 of each transmitter 2 are connected to reset terminals 8a, 8b of a timer 8 of a receiver 1. After a start switch 11 of the timer 8 is depressed in this state, the timer 3 is disconnected from the timer 8. Thus, the timers 3, 8 are synchronized, an output is given from the timer 3 of the transmitter 2 at a prescribed time interval and the transmission is attained during this time. On the other hand, the timer 8 of the receiver 1 outputs the reference signal corresponding to the transmission time of the transmitter 2 and a comparison circuit 9 measures the time shift between the receiving signal and the corresponding reference signal. When this shift exceeds a prescribed value, it is discriminated that radio interference is possible and a signal is transmitted from the circuit 9 to an alarm device 10.</p> |
