| 摘要 |
Device for detection of an intruder in a specified area, by virtue of the waves that the intruder makes while moving in the area, which are transmitted by the ground. In order to distinguish the waves produced by the passage of an intruder in the area 1, from the waves produced out of the area, materials, of a different nature to the original ground S, are spready in a layer 10 which covers the surface of the area; these materials are specially chosen on the basis of the noise that they produce when they are trod on: gravel, porcelain debris... Sensors C are associated with the layer 10 to receive the waves produced in this layer and transmit them, via a link L, to a surveillance installation. Application to the peripheral protection of buildings. <IMAGE>
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