Electronic and Mechanical Access Control

Ideally, an access control system ensures that only authorized personnel are permitted into or out of a controlled area. Entry can be controlled by locked fence gates, by locked doors to a building or rooms within a building, or by specially designed portals.

These means of entry control can be operated manually by receptionists and security officers or automatically by entry-control devices. In a manual system, security officers verify that a person is authorized to enter an area, usually by comparing a photograph on an access card and the personal characteristics of the individual requesting entry. In an automated system, the system presumes that the person bearing an entry-control device is authorized to enter or leave. Usually, the automated system is connected to locking mechanisms on doors or gates that open momentarily to permit passage. For maximum security, automated access control is backed up by human access control that verifies that the person entering is authorized to possess and use the entry control device.

All entry-control systems rely on three basic techniques—something a person knows, something a person has, or something a person is or does. Automated entry-control devices based on these techniques are grouped into three categories of devices—electronically coded, credential, and biometric.

Electronically coded devices operate on the principle that a person has been issued a code to enter through an entry-control device. This code must match the code stored in the device. Depending on the application, a single code can be used by all persons authorized to enter the controlled area or each authorized person can be assigned a unique code. Group codes are useful when the group is small and the controls are primarily to keep out the general public. Individual codes are usually required to control entry to more sensitive areas. Electronically coded devices presume that any person entering a correct code is authorized to enter the controlled area.