Abstract: A security installation for a property includes an imperforate protective barrier, a plurality of spaced posts extending upwardly from the top of the barrier and a plurality of spaced trip wires extending between the posts for detecting the presence of an intruder breaching, or attempting to breach, the barrier. The installation further includes a plurality of spaced posts protruding transversely from the inner side of the barrier, and a plurality of electrical wires extending between the posts. The electrical wires are adapted to impart at least a temporarily incapacitating shock to an intruder.

Abstract: A protective device includes a transmission line comprising two elongate co-extensive electrical conductors capable of sensing vibrations, converting these vibrations into electrical signals and transmitting the electrical signals. It also includes signal-processing means electrically connected to one pair of ends of the conductors. The signal-processing means includes normalizing means for normalizing the electrical signals, and a comparator for comparing the normalized signals with previously normalized known signals, thereby to identify the source of the signals transmitted along the cable, and hence an alarm/non-alarm condition.