TM 5-683/NAVFAC MO-116/AFJMAN 32-1083
the door be opened, even a fraction of an inch, or
commands to release locked doors under the card-
should another magnet be introduced in an attempt
access control subsystem. The remote multiplexer
to defeat it, the switch will change state and alarm.
may be microprocessor-based units, capable of data
Other devices for detection of an intruder may be
collection, communication with the host computer,
applied inside the building, including microwave
and performing limited-access control functions.
and infrared motion detection, photoelectric or laser
The security system provides location information
beams, seismic, sound detection, passive infrared,
as well as delay time for the guards. By successive
and other devices. Because all the doors are locked
detections, the security force can track the intruder
and alarmed, a means of allowing personnel to en-
and relay location information via portable radio
ter and leave must be provided. Positive-access con-
communications equipment to the responding
trol is established at the main guardhouse located
guards. In turn, the guards can constantly inform
at the perimeter fence. All persons with a need to
the security force on the progress of their work or
enter the protected area are screened by explosive
the need for additional assistance. The cameras,
detectors, metal detectors, and package X-ray detec-
using various means of target intensification, can
tion equipment. Once permitted access to the plant
"see" better than the human eye. Guard patrols are
protected area, they are only allowed into vital ar-
also used to detect unusual activity. Perimeter de-
eas within the plant on a need-to-enter basis. Con-
tection is accomplished by the application of elec-
trol of personnel movement into vital areas is by
tronic detection systems.
closed-circuit television/electronic-access control
(1) Microwave detection links. These devices
equipment. At each vital area door, split image
are mounted on posts inside the fence. Transmitters
closed-circuit television devices check the person
radiate amplitude modulated X-band energy and
receivers detect and process the received energy.
against his picture identification card. He then in-
Thus, an invisible energy envelope is produced that
serts his coded card into a magnetic reader, which
will detect an intruder.
sends the coded information to the access computer.
If the person has been authorized to enter the par-
(2) Infrared detection links. These devices are
postlike and mounted inside the fence. Transmitters
ticular vital area of the plant at that particular
time, the computer verifies the code and allows ac-
radiate multiple beams of modulated infrared en-
cess. The guard watches the entrance via wide-
ergy, and the receivers detect and process the en-
angle closed-circuit television to ensure that the
ergy. Penetration of the invisible infrared shield will
person enters alone. Using state-of-the-art circuit
alarm the system.
design and multiplexing communication techniques,
(3) E-field links. Transmitter wires and re-
the alarm monitoring systems offer a high degree of
ceiver wires are strung horizontally from mounting
tamper resistance. Redundancy is achieved by using
posts located inside the fence or mounted on the
a central alarm station and a separately located
fence. A radio-frequency energy field is generated
secondary alarm station. Electronic line supervision
around the wires. The intrusion of a person into the
or digitally encoded transmissions are used to pre-
invisible field will "short" energy, creating an alarm.
vent unauthorized persons from touching the sys-
(4) Buried sensor links. Devices sensing seis-
mic, pressure, (or electromagnetic disturbances for
tem wiring. Any tampering will cause an alarm.
a combination of these) are buried inside the fence
Access control, tamper indication, and administra-
and alarm upon the intrusion of someone into the
tive controls combine to prevent an insider from
field of detection.
attempting to sabotage the plant or help an outsider
penetrate the security system.
(5) Other systems. Other systems are available
that can be used in combination with the previously
10-5. Monitoring systems.
mentioned systems. The probability of detection by
these outdoor devices depends on their application.
Supervising the operations of the environmental
Perimeter detection equipment must be applied
conditions throughout a building can be achieved by
with consideration of the environmental limitations
the use of an integrated monitoring system. This
of the device's technology. Once the intruder has
system consists of a centrally located console cap-
penetrated the fence, he has entered what is called
able of continually monitoring many activities.
the protected area. Once again, visual or closed-
Console input signals may be initiated by pressure,
circuit television surveillance may detect the in-
temperature, speed, humidity, air flow, electric cur-
truder. Entry into a building is provided by the
rent, water, steam, sewage, or opening or closing of
application of a balanced magnetic switch on doors
electric contacts. With this system, an operator can
and openings. This device uses an internal bias
quickly determine the operating condition of any
magnet to balance a delicate reed switch in the field
number of sewage lift stations, air conditioning
of the external magnet attached to the door. Should
equipment, boiler auxiliaries or any other measur-