Looking to the 21st century

You may feel comfortable with infrared beams, but they are so 20th century. They also suffer from a major disadvantage, according to Bezuidenhout: because they operate on a point-to-point system, the beams can easily be bypassed by someone in the know.

Their more modern counterparts — outdoor digital dual-optic PIRs — sweep a 90-degree area and cover the ground to about 3m up, making them virtually impossible for intruders to avoid.

They can be fixed up to 36m from the receiver and can also be positioned to cover windows, since they see the glass as a wall and don't react to movement from inside.

Dual-optic PIRs are triggered by a combination of movement and heat. They have two lenses that cover the same area, each continually verifying the reaction of the other to prevent false alarms. Only when both sensors agree that a threat exists will they raise the alarm.

They ignore anything lower than 500mm and weighing less than 45kg (in other words, they won't be triggered by Fido or Fluffy). Internal settings allow you to tweak them to your specific requirements.

Indoor PIRs come in two types: the simplex and the duplex. Basically, the duplex sensors are pet-friendly and the simplex ones aren't. The pet-friendly version covers an area 11m square, remaining passive in the presence of animals weighing less than 18kg. It has a viewing angle of 88.5 degrees and a wireless range of 36m.

The only critical rule concerning indoor PIRs is that one unit must be installed to monitor the system's main box and prevent any malicious tampering.

The main box incorporates a radio that connects the system to your local security company. A transformer charges an internal battery to ensure that everything remains on line when the power goes down.

Home automation

An entry-level model covers about 16 zones and is perfect for townhouses, but if you are especially security-conscious, you could opt for a system with as many as 96 zones.

In fact, now you'd be entering the realm of home automation. Choose one of the more elaborate models and you can automate virtually anything from garage doors to sprinkler systems, lights and driveway gates. If you like, you could even link your system to a mobile network and control all the peripherals via cellphone.

And it can be armed or disarmed remotely via a PC and ASDL line.

An alarm memory key is also available so you can download to a memory stick and save all the complex programming that makes your alarm system unique. Then, if your system is disabled — by lightning, for example — all you need do is install a new PC board and use the memory stick to restore your security system's memory.

At last, Fearon is a happy man. His family feels safer, and Max, his best buddy, is no longer obliged to stand guard at the gate. Max now spends his free time — of which he has rather a lot — harassing passers-by. Don't ask us why... it's a dog thing.

Fearon eyes an impressive pile of obsolete sensors and superfluous security gates, all wrapped up in a tangle of wires. He doesn't feel even slightly sentimental. In fact, he plans to dump the lot without a second thought.

For more information on this and other security systems, visit www.shop4security.co.za.