Components of Access Control Systems
An Access Control point can be a elevator, parking barrier, door, etc which has to be given permission which can be elctronically controlled. Mostly the access point is the door. There are many parts of a access control system. The most basic is the electronic lock which has a awitch to open it. This works not with a key but a reader. The reader has a code pad where the code is entered. Readers do not usually make an access decision but send a card number to an access control panel that verifies the number against an access list.
To monitor the door position a magnetic door switch is used. Only the entry is controlled not the exit. To exit a Request-to-exit device can be a push button or a motion detector. When the button is pressed the motion detector detects the motion in the doo and the door alarm ignored the door is opened. In cases where the lock must be electrically unlocked on exit, the request-to-exit device also unlocks the door.
A credential can be a pin or number or a badge or a biometric feature or a combination of these. Mostly it is a card with magnetic stripe, bar code, Wiegand, 125 kHz proximity, contact smart cards, and contactless smart cards. Biometric technologies includes fingerprint, facial recognition, iris recognition, retinal scan, voice, and hand geometry.
A bar code as dicussed above is a series of alternate black and white bands which is to be read by a optical scanner. The width of the lines is the protocol used and code 39 is the most popular in security industry. This method is cheap, easy to generate making it suseptible to fraud.
Magnetic stripe technology, usually called mag-stripe, is so named because of the stripe of magnetic oxide tape that is laminated on a card. There are three tracks of data on the magnetic stripe. Typically the data on each of the tracks follows a specific encoding standard, but it is possible to encode any format on any track. A mag-stripe card is cheap compared to other card technologies and is easy to program.
Wiegand card technology is a patented technology using embedded ferromagnetic wires strategically positioned to create a unique pattern that generates the identification number. Like magnetic stripe or bar code, this card must be swiped through a reader to be read.
There are two types of Smart cards - contact and contactless. The diffrence between the two is the manner with which the microprocessor works. A contact smart card has eight contacts which has to be physically be inserted into the readr for the information to be read. A contactless smart card uses the same radio-based technology as the proximity card with the exception of the frequency band used
