Table 1.

Sensors used in intruder-detection systems.

Sensor	Reference	Limitation
Video	[4,5]	Requires several sensors to cover different areas that are nearby and apart Needs light to work Infrared camera is quite expensive Poses a threat in the sense of violating the privacy of a place
Motion	[6,7]	Blind spots Range limitations
Magnetic contact	[7]	Do not detect motion or other types of intrusions
Radar	[8]	Not recommended for indoor intruder detection Works properly only in the line-of-site transmission
Pulsed light	[9,11]	Quite high cost Not suitable for indoor applications
Vibration	[12]	Not suitable for indoor applications
Acoustic	[9,13,14,15]	Affected by environmental noise