The invention relates to a perimeter protection alarm
system, comprising an alarm
situation management center, a plurality of alarm hosts and a plurality of sets of
active infrared detectors, whereinthe alarm
situation management center and the alarm hosts are connected by a 485
bus; the plurality of sets of
active infrared detectors respectively form a plurality of coaxial protective rings withsequentially increasing radiuses, and the protective rings take the center of a protection area as the center; and each
protection ring corresponds to one alarm host, and the
infrared detectors constituting the
protection ring are connected to the alarm host corresponding to the
protection ring through a
CAN bus. The scheme of the invention utilizes an
active infrared detection technology to realize the security protection work in key areas, and the
system has the characteristics of
mature technology, high reliability, easy expansion, simple operation, good economy and the like. Since the plurality of sets of active
infrared detectors respectively form the plurality of coaxial protective rings with sequentially increasing radiuses, the hierarchical protection alarm for the key areas can beachieved, and moreover, through the arrangement of the multi-layer protection ring, the areas where criminals invade can be roughly judged, and the targeted alarm situation handling can be carried out.