Perimeter Security
Description: Taut wire sensors utilize either plain or barbed
wire strands attached to electro-mechanical sensors in order to detect
changes in tension on the fence fabric, rather than the vibration or
stress associated with fence disturbance sensors.
They are one of the most expensive fence sensor systems, because
of the laborious installation and maintenance time required. However
the exertion needed on the wire for an activation is substantial and
for this reason they offer very high detection rates and very low false
alarms.
Classification: Passive - Overt - Terrain Following
Application: Can be installed as a stand-alone fence creating
a dual-purpose physical barrier as well as a detection system or to
existing fence systems (subject to suitability) or even to roofs and
buildings etc. where such buildings may presents a weak spot.
Advantages: No terrain or environmental limitations, no
limit on length, extremely low false alarm rate, high probability of
detection
Possible Causes of Nuisance Alarms: Poor maintenance of the
fence or incorrect tensioning of the sensor wires will lead to unreliable
operation, medium to large animals.
Methods of Defeat: Tunnelling or bridging over the fence.
Description: Vibration detection sensors mounted on a fence
will detect frequency disturbances associated with sawing, cutting,
climbing or lifting of the fence.
Classification: Passive - Overt - Terrain Following
Application: Fitted to existing fence structures normally
in pairs 30 - 40cm apart with approx 3meters between each pair and which
are sited at approx 120 - 170cm above the ground.
Advantages: Inexpensive, easy to install, quickly fitted to
existing structures.
Possible Causes of Nuisance Alarms: Poor quality fence,
adverse weather conditions, animals, blown debris, vegetation.
Methods of Defeat: Tunnelling or bridging or careful removal
of fence fabric.
Description: An electric barrier fence offers not only an
enhanced physical barrier but also an alarm detection system providing,
deterrence, detection & delay to would be intruders.
The system can be fitted as a stand alone system or integrated
into existing fences and provides a sharp, non-lethal but painful
shock to anyone who comes into contact with the sensors as well as
triggering an alarm condition.
Classification: Active - Overt - Terrain Following
Application: Used where additional deterrence effect is
required and where it will cause additional delay to would be intruders.
Ideal in conjunction with below ground sensors in causing added activity
in the detection area.
Advantages: Primarily deterrence and delay, can also include
an audio sensor so that guards can 'listen in' to activity along the
fence.
Possible Causes of Nuisance Alarms: Anything coming in contact
with the fence such as birds and animals, blown debris, adverse weather,
overgrown vegetation.
Methods of Defeat: Tunnelling, bridging or bypassing the
circuitry.
Description: Ported coax or 'leaky cable' detection systems
generate an invisible electromagnetic field around the cables which
are normally buried in the ground to a depth of about 25cm (although
some systems can also be fitted to fences).
Systems require 2 cables 1 to transmit and 1 to receive (although
some systems can incorporate both sensors in a single cable). Cables
are normally laid 1m apart and a pair will provide a 4m wide detection
zone.
If an intruder enters the field he creates a disturbance and an
alarm is generated. Intelligent signalling processors eliminate many
causes of false alarms such as small animals etc.
Classification: Active - Covert - Terrain Following
Application: Where covert detection is required and where
fence mounted protection would be unsuitable.
Advantages: Covert protection and very low vulnerability
to defeat, low maintenance requirements and highly resilient to false
alarms.
Possible Causes of Nuisance Alarms: Large animals, fences
or other moving structures in the detection field, underground streams,
flooding.
Methods of Defeat: Deep tunnelling (below 1m) or bridging.
Description: Buried seismic sensors detect the low frequency
seismic energy created in the ground by someone or something crossing
through the detection zone around the sensors. Specialist analysers
interpret the signals and filter out much of the unwanted causes of
false alarms.
Classification: Passive - Covert - Terrain Following
Application: Specialist applications where particular
security issues are required (around a border post for example) or
where deep tunnelling may be expected.
Advantages: Can detect very low levels of seismic energy
and so can be used where a very high detection probability is required,
also can incorporate a microphone facility to enable guards to 'listen
in' to underground activity.
Possible Causes of Nuisance Alarms: Anything which may cause
seismic activity, animals, moving fences, large trees, telephone poles,
adverse weather, moving soil etc.
Methods of Defeat: Bridging.
 Previous Page Next Page
To view our Perimeter Protection PDF please click here.
To view our related Infra-Red Beam Product as a PDF please click Infra-Red Photo-Electric Beam.
To view our related Covert Below-ground System as a PDF please click Westminster Covert Below-ground Security System.
For more information - please click here to contact us.
|
