| 摘要 |
PURPOSE: To surely detect the presence/absence of reception input with simple constitution by using intermediate frequency signals as they are. CONSTITUTION: A counted value is reset by the gate timing pulses of a prescribed time interval and a counter part 101 counts reception IF signals until the next gate timing pulse is generated. A detection part 102 judges that it is normal in the case of counting the prescribed number of the reception IF signals in the time interval and judges that it is abnormal in the case of not counting the prescribed number and a signal transmission part 103 sends out the reception IF signals to a low-order station section when it is normal and also, when it is abnormal, interrupts signal transmission to the low-order station section or sends out IF carrier signals. |
