Crime prevention: security secrets from the dark days.

South Africa has turned to the boffins who once held the apartheid apparatus in place to find new ways to combat the waves of crime that are engulfing its citizens.

Security technology used to protect military personnel first experimented with two decades ago, is now reaching besieged homeowners in cities around the country. Scientists involved in the revival of the technology say are at the cutting edge of the battle against crime at the suburban level.

One such security system, Eagle Alert, is a wireless early-warning system that gives the alarm when an intruder enters a property--before he reaches the house. The system detects the intruder's body heat as he moves through the dark and instantly triggers the alarm.

The system comprises passive infrared weatherproof outdoor sensor units that can be nailed or stuck to walls or trees. The wireless nature of the apparatus means there are no trenches to be dug or wires to be laid and the units can be situated up to 80m distant from the radio control panel. The sensor beam is guaranteed to detect body heat up to 20 meters away, but has been positively tested at 80m. Arming and disarming the system is done with a portable remote. A built-in tamper-proof device sets off an alarm if the units are interfered with.