| 摘要 |
<p>Intrusion detector of the type in which the presence of an intruder is detected by infrared heat energy emitted by his body. An alarm signal is delivered when the level of radiation detected rises from the ambient level to a threshold level. A temperature responsive circuit adjusts the threshold level and so that the system has a relatively uniform detection range or sensitivity notwithstanding changes in the ambient temperature in the protected area.</p> |
