ABAT Sensors, Detectors & Detection Devices Flashcards
6 cards from real ABAT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 ABAT Sensors, Detectors & Detection Devices flashcards as text
What type of motion detector uses both microwave and passive infrared technology to reduce false alarms?
Answer: Dual-technology (dual-tech) detector
Dual-technology detectors require both the PIR and microwave sensing channels to trigger simultaneously, dramatically reducing false alarms caused by environmental factors that might fool a single-technology sensor.
A passive infrared (PIR) detector senses motion by detecting changes in which physical property?
Answer: Infrared radiation emitted by moving objects
PIR detectors are passive (they emit nothing) and detect the change in infrared heat energy emitted by a warm body (such as a person) as it moves through the sensor's detection zones.
What is the primary advantage of a recessed door contact over a surface-mount door contact?
Answer: Concealed installation that is tamper-resistant and aesthetically cleaner
Recessed door contacts are installed inside drilled holes in the door and frame, making them invisible and much harder for intruders to detect, defeat, or tamper with.
Which type of glass break detector analyzes the acoustic frequency profile of breaking glass rather than just sensing vibration?
Answer: Acoustic glass break detector
Acoustic glass break detectors use a microphone to analyze the audio spectrum of breaking glass, looking for the specific low-frequency thud followed by high-frequency shatter pattern.
A magnetic door contact generates an alarm when the door is opened because the magnet moves away from the reed switch. What is the normal (secured) state of the reed switch contacts?
Answer: Closed (normally closed / NC)
Standard alarm door contacts use normally closed (NC) reed switches; when the magnet is close (door shut), the contacts are held closed, and opening the door removes the magnetic field, opening the circuit and triggering an alarm.
What is the maximum recommended gap between a magnetic door contact and its corresponding magnet for reliable operation?
Answer: 1/2 inch (12 mm)
Most standard magnetic door contacts are specified to operate reliably with a gap of up to 1/2 inch (12 mm) between the magnet and the switch body; wider gaps may cause false alarms or missed detections.