Fence alarm options vary enormously from what I've read both in type and quality and it's important to get it right first time if you are serious about your perimeter fence protection.
One of the most proven and popular types of fence alarm is a cable type system where a special high quality cable is discreetly installed on the inside of the fence. Special analysers come as part of the package. Their purpose is to detect any signals emitted by the special cable. Signals can vary indicating the type of attack or intrusion attempt and the analyser works this out. You can even modify the detection criteria for attempts at climbing and cutting the fence.
A fence alarm of this nature has other benefits too.
- It can be attached to an existing or a new fence.
- It has no moving parts so is stable and reliable in bad weather.
- It has an audio listen in facility.
- It has a proven high detection rate record.
There are lots of stories on the web featuring perimeter fence attacks. One notable one in London was when would-be diamond thieves smashed through a perimeter fence close to the O2 arena - using mechanical diggers of all things! You can read more in this article about some of the most famous British 'heists' ever attempted.