Access control systems rely on credentials to identify authorized users and determine whether access should be granted. A credential can take many forms, including cards, RFID tags, or vehicle license plates.
Three of the most commonly used credential technologies are radio frequency identification (RFID), proximity cards (Prox), and license plate recognition (LPR). Each technology uses a different method to identify users or vehicles and is suited for different types of access control environments.
Understanding how these credential technologies work and where they are most effective helps system designers and integrators select the appropriate solution for a given deployment.
What Are Access Control Credentials?
An access control credential is the identifying data presented to a reader or recognition system to request entry into a secured area.
When a credential is detected, the access control system verifies the identity against a database and determines whether access should be granted.
Credentials may take several forms:
- Card-based credentials such as proximity cards
- Radio frequency tags used in RFID systems
- Vehicle license plates detected by recognition cameras
Each technology uses different methods to capture and transmit identification data.
RFID Credentials
Radio frequency identification (RFID) uses radio waves to communicate between a reader and a transponder tag. The tag contains a unique identifier that is transmitted when the reader energizes the tag.
RFID credentials can be embedded in cards, windshield tags, or other transponders.
RFID systems are widely used in access control environments where users or vehicles need to be identified automatically without physical contact.
How RFID Identification Works
An RFID reader transmits a radio signal that activates nearby tags. When a tag enters the reader’s field, it responds by transmitting its encoded identifier back to the reader.
The reader forwards the credential data to the access control system for verification.
Depending on the RFID technology used, read ranges may vary from a few centimeters to several meters.
Common RFID Applications
RFID is commonly used in:
- Vehicle access control systems
- Parking facilities
- Gated communities
- Fleet management systems
- Industrial access control
In vehicle applications, RFID windshield tags allow drivers to enter secured areas without stopping or presenting a physical credential.
Proximity Card Credentials
Proximity cards, commonly referred to as Prox cards, are one of the most widely used credential technologies in building access control systems.
These cards contain a low-frequency RFID chip that communicates with a proximity reader when placed near the reader surface.
Prox cards are commonly used for pedestrian doors, office buildings, and employee access control systems.
How Proximity Cards Work
A proximity reader emits a low-frequency radio field that powers the card’s internal chip. When the card enters the reader’s field, the chip transmits its encoded identification number.
The access control system then verifies the credential and grants or denies access.
Most proximity card systems have relatively short read ranges, typically requiring the user to present the card within a few inches of the reader.
Common Prox Applications
Proximity cards are frequently used in:
- Office building access control
- Employee badge systems
- Parking garage entry points
- Campus facilities
- Commercial buildings
Their simplicity and reliability have made them a long-standing standard in many access control deployments.
License Plate Recognition (LPR)
License plate recognition (LPR) systems use cameras and image processing software to identify vehicles by reading the characters on a vehicle’s license plate.
Instead of using a physical credential, the license plate itself becomes the identifying credential.
LPR technology is widely used in parking systems, gated access control, and traffic management applications.
How LPR Identification Works
An LPR camera captures an image of an approaching vehicle. Software analyzes the image and extracts the license plate number using optical character recognition techniques.
The extracted plate number is then compared against an access control database to determine whether the vehicle is authorized.
Because the credential is the vehicle’s license plate, drivers do not need to carry a card or tag.
Common LPR Applications
License plate recognition systems are commonly used in:
- Parking access control
- Residential gated communities
- Commercial parking facilities
- Campus security systems
- Transportation monitoring systems
LPR provides a convenient hands-free identification method for vehicle access environments.
Comparing RFID, Prox, and LPR Technologies
While RFID, Prox cards, and LPR all function as access control credentials, they differ in several important ways.
Credential Type
Prox systems use physical cards carried by users.
RFID systems use radio frequency tags that may be embedded in cards or mounted on vehicles.
LPR systems use the vehicle’s license plate as the credential.
Read Range
Proximity card systems typically operate at short ranges of a few inches.
RFID systems can support longer read ranges depending on the technology used.
LPR systems identify vehicles using camera imaging and do not rely on radio communication.
User Interaction
Prox systems usually require the user to present the card to the reader.
RFID vehicle tags allow identification without stopping or physically presenting a credential.
LPR systems require no driver interaction, as the vehicle plate is automatically detected by the camera.
Security Considerations
Security levels vary depending on the technology and system configuration.
Encrypted RFID credentials and secure access control systems can provide strong authentication.
Proximity cards may use simpler credential structures.
LPR systems rely on accurate image capture and database validation of plate numbers.
Choosing the Right Credential Technology
The most appropriate credential technology depends on several factors, including system requirements, environment, and user behavior.
Proximity cards are commonly used for pedestrian access in buildings.
RFID systems are frequently used for vehicle access where longer read ranges and hands-free operation are required.
LPR systems are often deployed when a physical credential is not desired and the license plate itself can serve as the identifier.
In many installations, multiple credential technologies may be used together to support different access scenarios.
RFID and LPR in Vehicle Access Systems
Vehicle access control systems frequently use either RFID tags or license plate recognition cameras to identify authorized vehicles.
RFID tags provide consistent identification through radio communication with dedicated readers.
LPR cameras identify vehicles visually using image processing techniques.
TagMaster North America provides RFID and LPR solutions designed to integrate with modern access control systems using industry communication standards such as Wiegand and OSDP.
Key Takeaways
RFID, proximity cards, and license plate recognition are three widely used credential technologies in access control systems.
Proximity cards are commonly used for building access.
RFID systems enable hands-free vehicle identification using radio frequency tags.
LPR systems identify vehicles using license plate recognition cameras.
Understanding the strengths and limitations of each technology helps system designers and integrators select the most appropriate solution for their access control deployment.