FlexZone Product Guide
Page 69
The Threshold is the received signal strength at which an Event is added to the Event Count. It is
measured in dB and can be set globally for the full length of detecting cable. An independent
Threshold can also be set for each defined cable segment.
•
When the rising edge of the received signal from the sensor cable exceeds the Threshold, the
Event Count is incremented by one.
•
The next Event will not be recorded until the period specified by the Event Window has
expired.
•
Once the Event Window time has expired, when the rising edge of the received signal from the
sensor cable exceeds the Threshold, the Event Count is incremented by one.
•
If the received signal remains above the Threshold for the period specified by the Event
Window (i.e., a climbing intrusion) the Event Count is incremented by one.
•
Each time the Event Count is incremented, the Alarm Window time is reset to zero.
•
When the value specified as the Event Count is reached within the Alarm Window time, a
sensor alarm is triggered, and the Event Count is reset to zero.
•
If the Alarm Window Time expires the Event Count is reset to zero without triggering an alarm.
Intruder detection
The FlexZone sensor guards against three intrusion scenarios:
•
An intruder attempts to cut through the fence fabric.
•
An intruder attempts to climb over the fence.
•
An intruder attempts to crawl under the fence by lifting the fence fabric.
An intrusion alarm resets automatically when the event is over or when the Alarm Hold Time
lapses. The Alarm Hold Time is a factory setting which is used to prevent subsequent alarms from
being declared at the same location. The Alarm Hold Time is three seconds, and cannot be
adjusted. Once the processor declares an alarm at a location, another alarm will not be triggered
at that location for three seconds.
Intrusion detection
Cutting the fence fabric produces a high amplitude signal that exceeds the Threshold. The first
time the detection signal exceeds the Threshold, the Event Count is incremented, and the Alarm
Window time count begins. The Event Window time setting must lapse before another Event will
be counted. Each time the Event Count is incremented the Alarm Window time count is reset to
zero. When the Event Count reaches the specified value within the Alarm Window time setting, the
system generates a sensor alarm. If a subsequent Event is not recorded before the Alarm Window
time runs out, the Event Count and the Alarm Window reset to zero.
When an intruder attempts to climb over the fence, or lift the fence fabric, a large number of energy
pulses rapidly occur causing the received signal to exceed the Threshold. When the signal first
exceeds the Threshold, the Event Count is incremented by one, and the Alarm Window time count
begins. Typically, during a climb or lift type intrusion, the received signal remains above the
Threshold as a result of the continued flexing and stressing of the fence fabric. The initial contact
with the fence activates the Event Window time counter. Each time the Event Window time is
reached, and the received signal strength remains above the Threshold, the Event Count is
incremented by one. Each time the Event Count is incremented the Alarm Window time count is
reset to zero. When the Event Count reaches the specified number within the Alarm Window time
period, the processor generates a sensor alarm at that location.
Содержание FlexZone
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