| 摘要 |
A signalling apparatus with pressure sensors, in particular for sensing intrusion into a closed surface area, with a yielding pipe embedded underground along the periphery of the surface area and filled with fluid; the pipe being divided into two separate sections by a deformable baffle plate to which are connected sensor means for supplying a signal depending on the deformation of said baffle plate, for initiating signalling means when said baffle plate is deformed.
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