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 the system. Attempts to alter the code strip should result in irreparable
damage to the strip and inoperability of the card.
5.2.2.7 Proximity Reader. The proximity reader generates weak radio
signals, some of which are absorbed and reflected by the card. The receiver
sends the resonated information along to the controller for code comparison
and access authorization. The reader attributes permit mounting behind
materials which pass radio frequencies -- glass, wood, plaster, and plastic
-- if the 4- to 6-inch proximity of card to reader can be attained. This
feature can enhance aesthetics but may inhibit service and relocation of the
device. The reader should be protected from vandalism and physical attack.
5.2.2.8 Capacitance Reader. The capacitance reader passes weak electrical
current to the capacitor plates imbedded within the card. The absorption of
the electrical energy at specific points on the capacitor array is the coded
information. The influences which inhibit electrical continuity from the
reader to the card must be avoided. The card is subject to poor contact
problems.
5.2.2.9 Active Electronic Reader. In this technology the reader supplies
current to the transmitter contained within the card. Further, this
insertion reader enhances and transmits the signal to the controller
electronics. This technology as well as others is being improved,
particularly in the area of circuit miniaturization. The durability of
cards, too, has been improved.
5.2.2.10 General. Since the insertion, swipe, receiver, and proximity
reader types are all located on the edge of the protected perimeter, they
are all affected by an environment which is difficult to control. Direct
physical attack upon the reader is not uncommon. Compromise of connection
wires and application of foreign voltages, and insertion of foreign objects
and substances (including but not limited to: debris, sticks, coins, chewing
gum, "Superglue," ice, liquids, or chemicals) are vulnerabilities of varying
degrees for all readers. The above effects can be diminished by sheltering
(including sun shading) of the reader to mitigate the adverse environment.
The best protection from the human attack is afforded by surveillance and
early detection of attacks. In all cases, no system should be implemented
which permits unauthorized access by the manipulation of electronics outside
the protected perimeter.
5.2.3 Electric Door Locks. Locking hardware that is compatible with
automated access control systems are electric strikes, electric bolts, and
electromagnetic locks. Each of these devices is available with one of two
features termed "fail-safe" and "fail-secure" configured in either
alternating or direct current in a range of 6 to 240 volts. The design of
an automated access control system must consider such variables which are
related to portal use and application of local and national fire and
electrical codes.
5.2.3.1 Electric Strikes. The electric strike is the most commonly used
electric lock. This device provides a depression or channel that fits the
13.02-75
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