Need to guard 20 miles of fence? "Listening" fence may be your spider-sense answer.
Chain link fencing between up right posts is not shown. Modified record player magnetic pick-ups in ground along fence ( one sensor can monitor 1000 feet of fence) register slightest vibrations of fence. Fence climbing, cutting, or trying to dig under will set off senor. Even a dog or rabbit contacts the fence will sound the alarm. Listening speakers along the fence can help guard identify what the disturbance could be.
