Applied Methods and Techniques Flashcards

What are the three primary performance characteristics used to evaluate an intrusion sensor?

Answer: Probability of detection, nuisance alarm rate, and vulnerability to defeat

Sensor performance is judged by how well it detects, how often it nuisance alarms, and how easily it can be defeated.

An alarm triggered by a deer crossing the perimeter is classified as what?

Answer: A nuisance alarm

Nuisance alarms come from real but non-threatening stimuli such as animals or weather, while false alarms come from equipment faults.

A passive infrared (PIR) motion sensor is most sensitive to an intruder moving in which direction?

Answer: Across the sensor's field of view

PIR detects changes in thermal energy across its zones, so crossing movement triggers it most reliably.

A monostatic microwave motion sensor is most sensitive to which type of movement?

Answer: Movement toward or away from the sensor

Microwave sensors rely on Doppler shift, which is strongest for radial motion toward or away from the unit.

Why are dual-technology (e.g., PIR plus microwave) sensors commonly used?

Answer: To reduce nuisance alarms by requiring both technologies to activate

Requiring both technologies to agree filters out environmental causes that would trigger only one.

In video system design, which task requires the highest pixel density on target?

Answer: Identification

Identifying a specific person beyond reasonable doubt needs far more pixels per foot than detecting presence.

What is the main role of alarm assessment in a physical protection system?

Answer: To determine whether an alarm is caused by an actual threat or a nuisance/false source

Assessment confirms the cause of an alarm so the right response can be dispatched.