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 greater than one reporting device.
Specific status is always relayed to
individual zones of alarm.
8.4.2.1 Alarm. The status of alarm is indicated by visual and audible
indicators in the event of a sensor detection of a violation. The visual
representation of a red-colored light and an appropriate tone sounder or
siren are the usual indicators. A steady light and tone normally indicates
an intrusion alarm and an intermittent light and tone normally indicates a
fire alarm. Careful differentiation of alarm indications should be made
from other event reporting to call attention to the matter with the greatest
urgency and clarity. Visual indicators are best for this purpose. Caution
is advised in the use of differentiated audible tones for alarm annunciation
as it has been proven to be unmanageable and confusing in systems requiring
more than four specific tone annunciations.
8.4.2.2 Access. The indication and reporting of access refers to the
condition where alarm devices are ignored due to an expected time or event
related violation of detection devices. This violation must occur when a
protected premise is entered. There are two methods which accomplish the
access mode: shunting and masking. Shunting removes the reporting zone
physically from the system by creating an open or short circuit in place of
the alarm zone. The disadvantage of this technique is the loss of trouble
reporting which creates a vulnerability to system maintenance during the
shunt period. Masking is a technique which ignores only the alarm reporting
and allows status of communication line to be maintained. Access conditions
should be limited to the smallest number possible to avoid facility
penetration during downtime and should be compensated for by procedures and
additional security forces as required.
8.4.2.3 Trouble. The indication of trouble will only be present with
systems sophisticated enough to provide this feature. Most systems (except
for microprocessor based or computerized) rely on the obvious loss of
communication or inhibit feature to indicate trouble. Trouble can be one or
all, short, open, ground, or foreign voltage, i.e., any condition which
inhibits the use of the report transmission facilities. Trouble indications
require communications or current to be present on the line at all times.
Interruptions or changes to the signal are the sense of trouble or line
fault. Malfunctions and tampering are thus controlled by line supervision
techniques.
8.4.2.4 Secure. This visual or audible signal is present when current or
communication can be carried on the signal transmission facilities and the
sensors are "armed." Some systems rely on the absence of secure indication
to indicate trouble. Simple systems will have a "ready" or secure indicator
to indicate closed loop status prior to arming the alarm circuits. This
indication is very important to the proper maintenance of the intrusion
detection system.
8.4.3 Hard Copy Output. Hard copy output refers to the alarm report
indications that is in printed form. This printed information may be a
simple
13.02-124
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