
Security factors
Page 8
FlexPS Product Guide
Security factors
There are many important factors to consider when planning a fence-mounted perimeter security
system:
•
Fence height - The fence must be high enough to present an effective barrier to climb-over
intrusions. It should also include climb-over deterrent hardware such as barbed wire or razor
ribbon. Senstar recommends that the minimum fence height for a FlexPS installation be 2.5 m
(8 ft.). A lower fence can be quickly and easily breached with a climbing aid such as a ladder.
•
Fence condition - FlexPS detects intrusions by picking up the minute vibrations or fence noise
caused by an intrusion attempt. Therefore, the fence must be in good condition to prevent any
metal on metal contact or vibrations caused by environmental effects. It may be necessary to
upgrade the perimeter fences to ensure they present sufficient barriers against climb over and
crawl under intrusions. If you are not sure of the suitability of your fence for a FlexPS sensor,
Senstar recommends hiring a local fencing contractor to inspect, and if required, repair the
fence.
•
Alarm assessment/response - What happens when the system triggers an alarm? Can the
alarm be assessed visually? Does the site include CCTV coverage to verify the event? Does
an operator monitor the system? Does the system contact a remote monitoring service? How
long does it take the alarm response to arrive at the zone? Does the system activate sirens
and lights to deter an intruder?
•
Probability of detection (Pd) vs. nuisance alarm rate (NAR) - With a fence-mounted intrusion
detection system there is always a trade-off between the probability of detection and the
nuisance alarm rate. A properly calibrated system will provide a high Pd by matching the
sensor’s sensitivity (cable gain) to the fence and cable type.
Fence structures
All fence panels in a sensor zone should be similar in type, size and condition. Ensure that there
are no loose panels, fittings or metal parts that can move and cause nuisance alarms. A shake test
in which you grip the fence fabric in the middle of a panel and gently shake it back and forth with
an increasing motion will help identify any loose pieces. Listen for metal-on-metal contact and
correct any problems found. Verify that there are no washouts or depressions under the fence that
could allow an intruder access. Ensure that there is no vegetation or other objects that can make
contact with the fence in windy conditions.