Which of the following can affect the performance of a PIR detector?

Temperature fluctuations can significantly affect the performance of a passive infrared (PIR) detector. These detectors operate by sensing the infrared radiation emitted by objects, particularly warm bodies like humans and animals. When the ambient temperature changes substantially, it can alter the background infrared levels, making it harder for the detector to differentiate between the background and potential intruders. For example, if the temperature of the surrounding area rises, the PIR may become less sensitive or may generate false alarms due to the diminished contrast between the heat sources it is intended to detect and the surrounding environment.

In contrast, while other factors like wet conditions can influence performance by potentially creating obstructions or affecting the sensor's ability to detect changes in infrared radiation, the direct impact of temperature fluctuations is more pronounced due to the fundamental principles of how PIR detectors operate. Advanced technology settings may enhance performance under certain circumstances but do not have a universal effect on all detectors, and magnetic interference generally does not play a significant role in their functionality.