Passive Proximity Readers
Nearly all building access cards based on proximity are passive. There are roughly 125 million cards used for accessing secured buildings today.
Passive technology implies there is no battery or power source required in the card. The proximity reader constantly transmits a low level fixed RF signal that transmits energy to the card. When the card is held at a certain distance from the reader, the RF signal is absorbed by a small coil inside the card and powers the card’s chip which contains a unique identification code. Once powered, the card transmits the code to the reader.
The advantages of proximity over other technologies are numerous: no moving parts, no mechanical wear, no slots, no read heads to maintain. The reader can be concealed inside walls or special enclosures and, even when the reader is surface mounted, it has no openings to jam or tamper. The card is the most secure and practically impossible to duplicate. Cards can usually be read through a purse or wallet and through most other nonmetallic materials. Card and reader orientation is not critical.
Reading ranges depend primarily on the reader. The larger the reading range, the larger the reader’s concealed antenna and hence, the size of the reader. There is a great variety of proximity readers designed for different environments including vandal-resistant mullion mount, smaller decor style and integrated keypad/reader units.
Active Proximity Readers
Active proximity technology implies there is a battery within the card. Since the card has power the range is greatly expanded (3-15 feet vs. 1-5 inches). The RF signal is low level (<1mw) but the frequency used is much higher. Applications tend to be uniquely applied, although recently the application in computer access control is more prevalent.
Orientation of the card and reader become important. Since the RF frequency is much higher several other effects may be noticed such as exact distance due to the fact that the signal bounces off of other object.
Active technology is useful where a hands-free (as opposed to contactless) data exchange is required. Since the range is much longer, it is generally not very practical for door access (except gated parking lots) since walking past the door may unlock the room. The typical application is to detect the presence of a person at a computer and allow access without intervention. Equally important is to automatically lock the computer when a person steps away.
Read range is adjustable between 3 to 15 feet.
Active cards are generally thicker (1/5 inch) as a result of the replaceable battery requirement
Presence Detectors
Sonar technology is a relatively new entrant as a tool for security with PCs.
In computer security there are two primary components to consider:
- Unlocking the ‘locked’ workstation, and
- Locking the workstation after the logon user leaves the station.
The first component generally gets the most attention and array of solutions while the second is generally handled by a time-out screen saver or company mandated policy. Both solutions for ‘2’ above are fraught with exposure issues.
The use of sonar technology is a means for detecting the presence or absence of an individual, and performing a specific operation when there is a change. It is important to understand there is no real identification of the user performed with this technology.
When a user steps away from an authorized session, the sonar device can detect this occurrence and send the appropriate keystrokes to secure the workstation (log off or lock). This improves solutions associated with policy since the device never forgets to lock. It is also a great improvement over a time-out in that this occurs immediately as opposed to a parameter set by the minute(s).
Likewise when the user steps up to a locked workstation, the appropriate keystrokes can be set to call up the logon dialog.
This technology can be a great aid for other forms of authentication such as biometrics.
Pongee Industries Co., Ltd. is the company of specializing in proximity reader, writer, and programmer. They also provide kinds of high quality access controllers for customers to select. Need more information, welcome to visit the Pongee’s website and feel free to contact with them.
Article Source: https://www.rfideas.com/support/learning-center/proximity-reader-technologies
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