PIDS sensors include fence-mounted vibration and taut-wire sensors, buried fibre and pressure sensors, ground surveillance radar, thermal imaging and video analytics. A PIDS is characterised by its probability of detection for defined threats, its nuisance alarm rate, and — once delays and response are considered — the probability of interruption it supports. Elevated and movable sensors extend detection beyond the fence onto approaches, where it buys the most response time.
Performance is conditional
A PIDS has no single probability of detection. It has a Pd for a crawling intruder at night in rain on zone 7, and a different one for a running intruder in daylight on zone 2. Specifications that quote one number without a threat definition are not comparable. Acceptance testing should use defined intruder types, approaches and conditions, and the operating record should track nuisance alarms per zone over time.
Design order
Threat definition → response time → alarm budget → detection placement → sensor selection → baseline and tuning.