A basic introduction to access control systems

The purpose of this page is to provide basic information on the various levels of access control systems currently available.

Digital Keypad Systems

These systems do not use cards, but rely on the punching in of a common number in order to release the door locking mechanism. They are simple and robust, and can be used as stand-alone units or can, in some cases, be linked together to cover more than one door.

The systems have a number of limitations. All users must be aware of the code number, which must be memorised. It is possible for a person using the code to be seen as they enter the code. In order to minimise this risk, the code must be changed regularly. These, therefore, should only be used in low security applications.

Systems using Magnetic Stripe Cards

These cards are very similar to the traditional type of credit card, and have a magnetic stripe on the reverse side. The card is swiped through the reader to allow access. The reader can also be provided with a digital keypad in order to achieve a greater level of security. The limitations with this type of system are the cards. Cards are susceptible to damage and the magnetic stripe can wear out. As the credit card companies have found, these cards are easy to copy. The information on the card can be erased by the presence of a magnet.

Weigand Effect Cards

The Weigand card has a series of wires embedded within it. These wires provide a code, which is read by means of induction when passed through a card reader. The cards are thicker than the magnetic stripe card and thus more robust. They are also difficult to duplicate and are weather resistant. These cards must be specially ordered from the manufacturers and can be subject to very long delivery.

Proximity Cards and Tags – long or short range

Proximity systems are by far the most popular type of card reading system. The system readers emit a field of radio frequency. When the card is introduced to the field, it acts as an aerial and transmits back its code to the reader. The system compares the data received with its stored data. If the data is valid, the system releases the locking mechanism.

The cards come in two types: long range and short range. Long range cards often have a battery in the card to extend the range. The latest developments have focussed on the field generated by the readers, increasing it to allow full hands-free reading of the card or tag. Special tags can be attached to cars in order to allow the use of road loops to open gates and barriers.

Smart Cards

With the introduction of the new banking credit cards, the smart card has become more popular, and is set to replace the proximity card. A smart card has 16 or 32 sectors of approximately 1Kb, which can store different types of data. Generally, two of the sectors are set aside for system data, leaving the remaining sectors to be used for access control, cashless payment system, personal data, etc.

The reader fields are increasingly becoming larger and able to read multiple cards within their fields. These are the cards of choice for the future.

Biometric Systems

For many years, the biometric systems have been viewed as unreliable. Systems have, however, improved within the past few years to such an extent that they are becoming more reliable.

These systems utilise unique physiological characterisations such as facial recognition, voice recognition, retinal information, palm prints and fingerprints. With increased use these reading systems will become more cost effective. The proposed National Identity Card system will be based on at least one of these technologies.

Access control system

Once the type of reader has been established, it needs to be associated with a control system in order that the datat from the reader can be usefully processed.

It must be remembered that the use to which the system is to be put will decide the complexity of the control system. It is easy to over-engineer systems and thus overprice the system in terms of its eventual application.

In surveying the system, consideration will need to be given to the amount of people in the building, the level of security required and who has access to specific locations. Is the system to be computer based or stand-alone and who will be responsible for the management of the system?

Consideration also needs to be given to future development. Will the system be dedicated to the one site or will it be expanded to other sites to allow the monitoring of security from a remote location?

Time spent in establishing full current requirements and future planning is an important element of the survey.

Single site basic access control system

This is the most basic access control example.

Site specifications

The client has a single office with two exits. There are 25 employees altogether. There are no intrusion points.

Solution

• 1 control panel
• 1 LCD keypad
• 1 2-door controller
• 2 readers
• 1 package of 25 cards, programmed 36 bit

 

Note: For a single site, you can control and program the system using a simple LCD keypad.

Single site basic access control system with intrusion

Site specifications

The client  has a single office with two exits. There are 25 employees altogether. There are 24 intrusion points.

Solution

• 1 control panel
• 1 LCD keypad
• 1 2-door controller
• 2 readers
• 1 package of 25 cards, programmed 36 bit
• 1 16-point expander

 

Note: This system is identical to the previous example. We have simply added a 16-point expander module.

Upgrading from a single site access control system to multiple sites (networked)

We start from the previous example, where we brought the following equipment:

• 1 control panel
• 1 LCD keypad
• 1 2-door controller
• 2 mullion readers
• 1 package of 25 cards, programmed 36 bit
• 1 16-point expander

Site Specifications

In addition to the first site that we installed (2 exits, 25 employees, 24 intrusion points), the client now has a second site with 40 employees, 2 doors and 24 intrusion points.

Solution

First of all, we will need to upgrade the original site software so that we can network it with the second site. Secondly, you will install the second site with:

• 1 control panel
• 1 LCD keypad
• 1 2-door controller
• 2 readers
• 2 packages of 25 cards, programmed 36 bit
• 1 16-point expander

 

Note: After upgrading your original site to the higher-level software, you install a second higher-level software 2-door system at the new site. Both systems communicate via the external modems. All information is accessible from the server PC at the original site.

References

• EN 50133-2-1:2000   Access control systems for use in security applications - General requirements for components.
• EN 50133-7:1999   Access control systems for use in security applications - Applications guide.
• EN 50102:1995   Degrees of protection provided by enclosures for electrical equipment against external mechanical impacts (IK code).
• EN 50130-5:1998   Alarm systems - Part 5: Environmental test methods.
• EN 50133-1:1997   Alarm systems - Access control systems for use in security applications - Part 1: System requirements.
• EN 60529:1991   Degrees of protection provided by enclosures (IP code) (IEC 60529:1989).