| 摘要 |
Five infrared sensors are located in different height positions between respective main bodies 10 A to 10 H, and all of these infrared sensors transmit and receive 35 infrared rays pulse-coded in conformity with a start-stop system. In addition, these pulse-coded infrared rays have the signal width of, for example, 450 mus, and are serially transmitted with a predetermined delay time in a period of 20 ms by a delayed synchronizing-signal. Intrusion surveillance is performed by identifying the pulse codes of these infrared rays. According to this, since not only interference among a plurality of infrared sensors is prevented, but also infrared rays are outputted in a short time, the occurrence of false alarms etc. decreases remarkably.
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