1. Why the perimeter
A camera inside the building sees a burglar only once they are already in. The perimeter sees them at the fence. The difference is time: minutes in which a response can start before damage is done.
2. How IR barriers work
An IR barrier sends beams of light between a transmitter and a receiver. Crossing breaks the beam and registers as an event. One line can cover from 100 to 700 metres, depending on the model.
3. Where they are placed
On the fence line, gate, approach. Barriers are placed on corners so the beams follow the protection line. The goal is that no entry passes unnoticed.
4. False alarms
Animals, wind and leaves can trigger sensors. Tuning the detection zone and position reduces false alarms. Verification in the centre tells them from real ones.
5. Perimeter and camera
The perimeter detects, the camera confirms. When a barrier triggers, the centre opens the picture from that location. Detection and picture work together, not apart.
6. Which buildings
Warehouses, depots, substations, industrial compounds — buildings with a clear fence line and values inside. For a house, the perimeter helps when there is a fenced yard.
7. Recommendation
If your building is vulnerable on approach rather than in the rooms, the perimeter is the first layer. It buys time — and time is what a response needs.
RULE OF THUMB: Detection at the fence, before entry. Every metre earlier is time the response gains.