The diagram shows the components of a simple... | Computer Science (9-1) 0984 | Paper 1 Mock 01 | Computer Systems

Question 1 Report

The diagram shows the components of a simple automated security system.

(a) Using the diagram, describe the sequence of events when the motion sensor detects movement. [4]

Answer

Answer Details

(a) When the motion sensor detects movement, the following sequence occurs:

The PIR (passive infrared) motion sensor detects a change in infrared radiation in its field of view, which happens when a warm body (a person or animal) moves through the monitored area. [1]
The sensor sends a signal to the microprocessor indicating that motion has been detected. [1]
The microprocessor processes this signal. If the security system is armed (i.e. in active monitoring mode), it simultaneously sends output signals to activate three responses: trigger the alarm siren to sound loudly, start the camera recording video of the area, and send an alert notification (e.g. text message or app notification) to the property owner or security monitoring service. [1]
These three responses happen simultaneously to maximise security effectiveness: the siren deters the intruder, the camera captures evidence, and the alert ensures someone is notified even if they are not on-site. [1]

The diagram shows the components of a simple automated security system. (a) Using the diagram, describe the sequence of events when the motion sensor detect...