NFGS 16726C, Basic Intrusion Detection Systems, NAVFAC Guide
Specification, April 1991.
NFGS 16727C, Commercial Intrusion Detection Systems, NAVFAC
Guide Specification, April 1991.
Function and Location
Function. In order that security guards can respond to an
intrusion, threat detection either by security personnel or by using a remote
intrusion detection system (IDS) is required. The function of an IDS is to
initiate the system response by detecting an overt attack against the
facility, covert entry threats, or unauthorized insiders after hours. IDS
performance parameters of concern include: completeness of coverage,
probability of detection, the alarm zone resolution, and false and nuisance
alarm rates. The use of IDS involves inherent risks. For example, guard
requirements for threat assessment may increase because of high false or
nuisance alarm rates associated with detection sensors. One way of
minimizing the latter problem is to design systems where the disturbance
threshold level for activating the sensor is high, but within the level of
that created by the intruder.
Location. IDS should be located to detect a penetration
attempt before any building barriers enclosing the protected area are
breached. If this is not done, the delay time offered by the barriers cannot
be counted in the overall delay which is compared to the guard force response
time. IDS systems are available that can be located on either barrier
surfaces, or to cover interior volumes within buildings. These are
summarized in the following.
Minimum Requirements. Minimum IDS requirements established by DoD
relate to exterior IDS systems rather than building interior systems. The
reader is referred to par. 4.5.3 for a discussion.
Detection at the Barrier. This section summarizes sensors used for
detection at the surfaces of walls, floors, ceilings, doors, windows, and
a) Vibration sensors. Vibration sensors, also called
"shock" sensors, are mechanical contact switches designed to activate when
the surface on which the sensor is mounted starts to vibrate. Rigid
materials such as reinforced concrete or masonry make excellent surfaces for