The Perimeter Intrusion Detection System (PIDS) is a combination of different kinds of surveillance systems, wherein Closed-Circuit Television (CCTV) cameras, infrared and etc.
The best defense is a good offense. That often-used sports principle applies to military applications. It is an axiom that applies to the security industry, as well. When it comes to perimeter security, though, a strong offense provides a good defense, but that defense will be only as strong as its weakest link.