Access Control Enterprise System (ACES):
What is a Card Access Control System?
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This document provides a quick summary of card access control systems, and introduces one of the latest technological innovations in such systems: wireless card access. In Section 2, the pros and cons of the new wireless technology are discussed, for those who are considering it as an option for their doors. (NOTE: For security reasons, wireless card access is only a choice for internal doors, not external doors. If you have an external door, you will only need to review Section 1.)
What is a Card Access Control System?
To help ensure that only authorized users can enter buildings and other structures, many institutions are implementing access control systems. A common approach is to issue access cards to users, which are scanned by electronic card readers at entry points. Once the system verifies them, the users can enter. Hotels, for example, often now provide guests with “key cards” that they use to enter their rooms.
These programmable systems have several advantages over physical locks and keys for administrators. They can easily replace lost keys and avoid the expense of rekeying locks, as well as monitor door traffic and implement an instant “lock-out” for security purposes. In these systems, there are many components that enable its smooth, automated operation—from the card readers to the central computer that stores the database of authorized users. Together, all of these components comprise a card access control system.
There are various ways of implementing these systems, but the simplest way of thinking about large-scale systems, such as the one at Stanford, is to break them into these three main pieces: Card reader/door lock, access controller, and server.
- Card reader/door lock
These are the gatekeepers that are installed at the door. In addition to the card reader, the standard equipment (also known as “field devices”) include a monitor that provides an alert if a person tries to enter without an approved card, an electrified door release that unlocks the door, and a request-to-exit device, so that users can exit without triggering an alarm. While card readers, locks, and related devices are separate technologies, there are also locksets that integrate the card reader with all the other standard field devices. - Access controller
This component, which is also referred to as the access control panel, controls the card reader and door equipment. The controller takes the input from the card reader and figures out whether to grant user access, and sends the signal to unlock the door. It communicates with a central server to access the main user database and handles commands (for example, to allow a door to be temporarily unlocked). - Server
The server provides a central point for managing the security system. It stores the complete database of cardholders, allows an administrator to set the parameters for access (for example, no access through side doors after 6 p.m.), and generates reports about traffic patterns, alerts, and so forth.
The diagram below shows the different components of a card access control system and how they are connected.
The distributed nature of these systems allows for flexibility in terms of installation and configuration, with the ability to upgrade as technology improves. In the future, for example, card readers could be replaced with biometric fingerprint readers or retinal eye scanners.
Wireless Card Access Control: Pros and Cons
One of the latest developments in card access control systems is wireless card access. The basic concept is simple: replace some of the wiring with a wireless connection.
Traditionally, card readers and door hardware have been wired, with cabling to the controller for communications and wires for power. These components can now be wirelessly connected to the controller, and equipped with batteries for power. The primary advantage with wireless is a reduction in installation costs. The primary disadvantage with wireless is reliability. Physical wiring, by its very nature, provides a more reliable communications channel -- and arguably, a more consistent power supply. (For this reason, Stanford’s policy is that card access control for external doors must always be hard-wired.)
The diagram below shows how the components of a card access control system can connect wirelessly.
An analysis of the wired vs. wireless options revolves around these considerations: accessibility, costs, reliability, and aesthetics.
- Accessibility
There may be difficult locations where running wires is impossible or extremely difficult, in which case a wireless solution allows card access control where it would not otherwise be possible. This is a common motivation for wireless applications. - Cost
Wireless card access control eliminates the need to access drop ceilings or install conduit to run wires to the door. By connecting the card reader and related devices wirelessly to the controller, installation time is cut considerably, which makes up a substantial portion of the system cost. And the costs of powering them with batteries and the associated labor over the lifetime of the system are still estimated to be a fraction of the costs of hard-wiring. However, note that this savings may be offset by the costs of the additional wireless equipment. For example, there are back-end modules that have to be added in order to provide wireless access. And at the door itself, depending on the card reader/door lock combination that is chosen, it may not be possible to eliminate all local wiring, since all those components need to be connected together and have a source of power. - Reliability
The inherent potential for disrupted communications between the controller and the card reader, lock, and related mechanisms is the primary drawback to wireless card access control. Most wireless card access control manufacturers use a radio frequency (RF) in the 900 MHz bandwidth range, for a range of about 200 to 275 feet (the security of the channel is protected by encryption). The chance of interference with the radio signal from other wireless devices is reduced by using spread-spectrum technology, which spreads the outgoing signal over a range of frequencies and combines them back into a single wavelength. However, severe radio noise or other extreme electrical activity can affect the connection, and there is also the chance that the wireless antenna and transmissions equipment itself may fail. In terms of battery reliability, most batteries in wireless card access control will last about four years, assuming typical door traffic patterns. Doors with heavy traffic may require annual battery replacement. Battery failure is a possibility. - Aesthetics
A visibly wired solution may have a less appealing look than a wireless one. However, a lock with a battery pack will also tend to have a thicker profile than one without. Depending on the particular door and door layout, the aesthetic considerations will vary.
Summary
Card access provides significant benefits for establishments that need to provide greater security for their buildings. In the implementation of a card access control system, administrators can choose either a wireless or wired installation for internal doors. In cases where hard-wiring would be prohibitively difficult or expensive, the wireless option is appealing. It also has the advantage of fast installation (and thereby lower cost, though the cost of the wireless equipment needs to be taken into account). Hard-wired solutions, on the other hand, provide a more reliable connection.
For additional technical information, or consultation on a specific installation, the Stanford IT department welcomes your inquiries. Please contact Jay Kohn, jkohn@stanford.edu.
