ABAT ABAT Sensors, Detectors & Detection Devices 2 — Questions and Answers
Question 1: Active infrared beam detectors generate an alarm when the invisible beam between the transmitter and receiver is interrupted. What is one major limitation of this detector type?
- They cannot detect motion faster than 3 mph
- They require a direct line of sight and can be defeated by slow low-crawl intrusion (Correct answer)
- They are only effective indoors due to solar interference
- They cannot be used on zones longer than 10 feet
Correct answer: They require a direct line of sight and can be defeated by slow low-crawl intrusion
Active IR beam detectors require unobstructed line of sight and can potentially be defeated by an intruder moving slowly below the beam height, which is why they are often stacked in multiple beams or combined with other sensor types.
Question 2: What does 'pet immunity' in a PIR motion detector typically mean?
- The detector ignores all motion below a programmable weight threshold, typically up to 40–80 lbs (Correct answer)
- The detector uses ultrasonic frequencies that animals cannot trigger
- The detector has a special lens that only covers the ceiling area
- The detector operates only at night when pets are sleeping
Correct answer: The detector ignores all motion below a programmable weight threshold, typically up to 40–80 lbs
Pet-immune PIR detectors use downward-angled lens patterns and sensitivity adjustments to ignore heat signatures below a certain mass/height threshold (commonly up to 40–80 lbs), allowing animals to move freely without triggering alarms.
Question 3: A seismic or vibration sensor is best suited for protecting which type of asset?
- Open perimeter areas and driveways
- Vaults, safes, and ATMs against physical attack (Correct answer)
- Motion inside a room with HVAC airflow
- Long glass storefront windows
Correct answer: Vaults, safes, and ATMs against physical attack
Seismic detectors sense the low-frequency vibrations produced by drilling, cutting, or impact attacks on hard surfaces, making them ideal for protecting vaults, safes, and ATMs from physical attacks.
Question 4: What type of sensor is best used to detect intruders crossing an outdoor perimeter such as a fence line?
- Passive infrared motion detector
- Microwave fence disturbance sensor or electrostatic sensor (Correct answer)
- Glass break detector
- Photoelectric smoke detector
Correct answer: Microwave fence disturbance sensor or electrostatic sensor
Microwave fence disturbance sensors or electrostatic field sensors are specifically designed to detect climbing, cutting, or lifting of fence panels along an outdoor perimeter.
Question 5: What causes 'range creep' in microwave motion detectors?
- Battery voltage drop reducing detection distance
- Microwave energy passing through walls and detecting motion in adjacent rooms or outside the building (Correct answer)
- Lens contamination reducing the detection pattern
- Software calibration drift over time
Correct answer: Microwave energy passing through walls and detecting motion in adjacent rooms or outside the building
Microwave signals penetrate non-metallic walls and materials, so a microwave detector can detect motion in unintended areas like adjacent rooms, stairwells, or even outside the building.
Question 6: When installing a PIR detector in a room with large windows facing south, what environmental concern must be addressed?
- Sunlight causes UV degradation of the PIR lens over time
- Direct sunlight or reflected heat from HVAC vents can cause false alarms (Correct answer)
- South-facing windows increase humidity that damages the IR sensor
- Magnetic interference from window frames affects reed switch sensitivity
Correct answer: Direct sunlight or reflected heat from HVAC vents can cause false alarms
PIR detectors sense changes in infrared heat; direct sunlight, clouds moving across the sun, or HVAC heat drafts can create sudden temperature changes that mimic a moving body and trigger false alarms.
ABAT ABAT Sensors, Detectors & Detection Devices 2
Active infrared beam detectors generate an alarm when the invisible beam between the transmitter and receiver is interrupted.
What is one major limitation of this detector type?