zone control unit shall alarm when a sufficient number of sensing
unit activations are sensed within a specified time period. Alarm
threshold shall be field adjustable by zone and shall [in
combination with adjustments to individual sensing units] permit
compensation for winds up to [40] [56] [_____] km/h [25] [35]
[_____] mph without increased nuisance alarms while maintaining
specified sensor performance. With sensitivity controls set at
approximately midrange, sensor shall alarm when an intruder
attempts to scale the fence or to climb undetected in areas of
reduced sensitivity, such as around poles and rigid supports.
Sensor shall alarm for attempted fence liftings or scalings,
including scalings assisted by climbing aids leaned against the
fence. Sensors shall allow gradual changes in fence position, due
to expansion, settling, and aging, without increased numbers of
nuisance alarms. Sensors shall be either tamper alarmed or
self-protecting. Exterior components shall be housed in rugged,
corrosion-resistant enclosures, protected from environmental
degradation. Provide sensor zone control unit housings with
tamper alarms. Fence cable support hardware shall be
weather-resistant. Interfacing between sensor zones and alarm
annunciators shall be carried in underground cables.
b.
Strain-sensitive cable sensors: Sensors shall detect movement on
a standard security chain link fence associated with an intruder
scaling, cutting through, or attempting to lift the fence fabric.
Entire sensor system, including sensor zone electronics, shall be
capable of mounting directly on the fence and exposed to the same
environmental conditions as the fence. Length of fence protected
shall have no dead zones where an intruder can penetrate the
fence, and through sensor electronics, shall be divided into [100
meter] [_____] zones. Sensing unit of sensor shall consist of
transducer cable capable of achieving specified performance either
by attachment directly to the fence fabric by plastic cable every
300 to 455 mm 12 to 18 inches or by installation inside EMT
conduit mounted on the fence. Sensing unit shall have equal
adjustable sensitivity throughout the entire length. To permit
installation in extreme EMI environments with no loss of detection
capability, only conventional waterproof coaxial cable connectors
shall be used for connections of the sensing unit. Entire sensor
system shall be capable of detecting tampering within each portion
of the system by sensor zone. Sensor zone electronic circuitry
shall provide capability for alarm threshold sensitivity
adjustment to permit compensation by zone for winds up to [40]
[56] [_____] km/h [25] [35] [_____] mph while maintaining the same
level of detection performance as under ambient conditions.
Sensor zone control unit shall provide an analog audio output for
interface to an external audio amplifier to permit remote audio
assessment regardless of sensor alarm status. Sensor zone control
unit alarm output interface shall be a separately supervised relay
contact normally open or normally closed, with [an adjustable
intrusion alarm pulse width of 0.5 second adjustable and a]
continuous (until corrected) tamper alarm.
c.
Electrostatic field sensors: Sensors shall initiate an alarm when
an intruder attempts to approach or scale a fence or physical
barrier. Electrostatic field sensors shall detect human presence
by generating an electric field around one or more horizontal
wires and sensing the induced signal in parallel sensing wires.
Sensor shall monitor the induced signal for changes that result
SECTION 13703N
Page 35
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