NCJ Number
101020
Editor(s)
S M Gallery
Date Published
1986
Length
18 pages
Annotation
This paper reviews some technological advances in alarms since World War II and presents definitions for 187 terms pertinent to fire and security alarms.
Abstract
Radar and sonar technologies developed during World War II have been used in the construction of alarms. The ultrasonic and microwave doppler motion detector sounds an alarm when it detects movement in an area that should not be occupied. Motion energy pushed at or away from the detector causes a frequency change that triggers the alarm. Modern capacitance detector sensors can be used to protect any metallic objects that can be separated from the building or earth ground. Safes or file cabinets are appropriate for capacitance protection, and museum paintings can be fitted with a metallic backing and protected against theft by night or vandalism by day with a capacitance detector. Anyone who approaches the protected object upsets the balance of the tuned antenna circuit of which the object is part. This triggers an alarm. The glossary defines the specialized technological terms used in the field of protection systems.