Surveillance Systems and Electronic Aids
Surveillance Systems and Electronic Aids tests CCTV types, camera placement, recording and evidence handling, plus alarms and intrusion detection.
CCTV essentials
- Camera types: fixed, PTZ (pan-tilt-zoom), dome, bullet, ANPR for number plates, thermal for perimeter work.
- Placement: cover entry and exit, cash counters, strong room, corridors and perimeter; avoid blind spots, direct sunlight and glare; mount gates at a height that allows facial capture.
- DORI: camera performance falls with distance - Detection, Observation, Recognition and Identification each need a different pixel density. A wide shot that shows a person may never identify a face.
- Recording: continuous or motion-based; check the date/time stamp; retention as per policy and law; time sync so footage matches the register.
- Evidence integrity: do not delete or edit; export a copy, record camera ID, time, date, operator and chain of custody; keep the original untouched.
- Privacy: no cameras in toilets, changing rooms or private spaces; signage where required; access to footage restricted.
- Alarm systems: intruder alarm, door contact, PIR motion sensor, vibration sensor, panic button, fire detection; treat an alarm as genuine until verified, and record the reset.
Worked example
A theft is reported at 14:20 but the footage clock shows 14:31. Reasoning: never assume the recorder is correct, and never assume the operator tampered with it. First check the time offset against the register, confirm which day is on screen, then export the relevant window with a written note of the offset.
Traps that cost marks
- Turning a camera away to 'cover' a colleague's absence.
- Showing CCTV footage to outsiders or playing it on a personal phone.