Principles of Operation.
This is because they are dependent on effectiveness and
They are also dependent upon cost and maintenance required.
No one system is suitable or adaptable to every site and environment. The
situations and conditions at the site to be protected determine which
devices or systems are efficient and practical.
b. These devices transmit an immediate warning signal, and they operate
on the following basic principles:
(2) Interruption of a light beam.
(3) Detection of sound.
(4) Detection of vibration.
(5) Detection of motion.
(6) Penetration of an electronic field.
(7) Detecting the sudden introduction of a heat source.
Classification of Sensors.
a. Intrusion detection sensors are designed for both interior and
exterior use. Sensors must be chosen based on intended use. For example,
interior sensors are ineffective when exterior perimeter protection is
b. All interior intrusion detection sensors are classified as to what
stage of intrusion they are meant to protect. The three classifications are
(1) Penetration through the perimeter.
Initial entry through
perimeter barriers is detected.
The opening of a window or door to a
protected area constitutes perimeter penetration. This can be detected by
(2) Movement inside the protected area. This type sensor is a motion
Energy patterns created by motion detectors change when an
intruder moves within a protected area.
The sensors automatically detect
the changes in energy patterns and respond accordingly.
(3) Point/removal coming in contact with the item being protected.
Touching or trying to remove a protected item, such as a vault or safe,
triggers the sensor.