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Security & Surveillance Solutions - Protecting People and Property |
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Glossary of Security Terms |
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| Glossary:
CCTV | Access Control | Access Control Card |
Security Systems |
 Glossary
of Access Control Card Terminology
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The
most common reader is called Proximity.
These systems use cards or tokens as a means of
identification. As the name implies, no direct contact is
required between the card and the reader for the system to
operate, the card must only be in the proximity of the
reader. The read range will vary depending upon the
card/token and the type of reader, from 1/2 inch to up to 33
feet. The reader generates an RF field which causes
specially designed wires in the card to resonate,
transferring the card information to the reader. These cards
are immune to electromagnetic and RF interference, and they
can offer "hands free" operation.
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Wiegand
cards are essentially magnetic field effect devices. As the
card is inserted or swiped through the reader an
electromagnetic field generated by the reader induces a
voltage in the card causing it to transmit its code. Unlike
some insertion type systems, wiegand readers are completely
sealed against weather conditions and as a result have a
long live span. These cards are difficult to duplicate,
highly damage resistant, and offer a high level of security,
but as with proximity cards expensive, and generally can
only be programmed by the manufacturer.
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Magnetic
stripe cards use the same technology that is
employed in credit cards, and are probably the most common
type of card in use. There are two types of magnetic cards,
low-coercivity and high-coercivity. The high-coercivity type
are less prone to accidental erasure and damage. Magnetic
stripe cards require that the card come in direct contact
with the reader head causing wear and a shorter life span.
This direct contact requirement also can cause misreads due
to dirt and debris accumulation in the reader. Certain
access control systems allow the user to utilize their
existing credit cards, eliminating the need to purchase
cards. The cards are low in cost but are easily duplicated,
are affected by outside magnetic fields, and the readers
require occasional cleaning to remove any dirt buildup on
the read heads.
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Bar
codes, employ a pattern of bars and spaces of
varying widths to represent the user information. This is
the same technology that is used by stores for inventory
control and check out counters. Since the bar code is
visible it is easy to duplicate and as such is not
considered to be a good choice for systems where security is
a major concern.
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Infrared
cards contain a series of bar codes, similar to standard bar
code cards, that are only visible when exposed to special
infrared light. When the card is exposed to the special
light, the bars cast a shadow behind the card which is then
read by the reader. They are relatively low in cost, very
reliable, not easily duplicated, and offer a good level of
security but can be difficult to laminate for use as an ID
card.
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Keypads
use a numeric pad, similar to that of a telephone. The user
simply presses his code into the keypad and the system reads
the numbers. This system does not require the user to carry
any special card or token but can less secure since unless
the user is very careful someone may see which numbers are
being pressed. Certain keypads overcome this drawback by
scrambling the number layout each time the keypad is used.
Keypads can be use either by themselves or for high security
in conjunction with some card reader technology. In this
manner the user must both present a card and enter a code
before access is granted.
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Biometric
systems measure some physical property of the user such as
hand geometry, retina pattern, or voice pattern. These type
of devices offer very high security but also are the most
expensive and require that the user be present in order to
be enrolled into the system.
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