Abstract: A wire fence alarm system 10 comprises a plurality of zones in which a wire or set of wires is stretched between two anchor posts. A sensing post includes sensors for detecting deflection of one of the wires and a processor for generating alarms responsive to signals from the sensors. One or more of the anchor posts comprise rotating members attached to the wires. Use of the anchor post to climb the fence will result in an imbalance in the forces applied to the rotating members by the wires, thereby initiating an alarm condition.

Abstract: A taut wire perimeter fence intrusion detection system is disclosed. The taut wire deflection sensors in the system each include a flexible housing into which is disposed a full resistance bridge having strain gages for each leg. Opposing strain gages in the bridge circuit have predominant directions in common directions. The strain gages are formed directly onto a printed circuit board. An amplifier circuit is also mounted onto the circuit board, for amplifying the differential bridge voltage from the bridge. The taut wire is connected to the housing, for example by way of a slotted bolt and nut, so that horizontal deflection of the taut wire creates strain on the circuit board which is sensed by the strain gage bridge, amplified by the amplifier, and communicated to a data processing system which generates the appropriate alarm condition.