Application of RFID Technology in Access Control System

Radio Frequency Identification (RFID, Radio Frequency Identification) technology is the application and development of automatic identification technology in radio technology. The basic principle is to use radio frequency mode to conduct non-contact two-way communication in order to achieve the purpose of identification and data exchange. Therefore, it can achieve multi-target recognition, moving target recognition and remote real-time monitoring and management. The communication distance can range from a few centimeters to several tens of meters. Its main advantages are its strong adaptability to the environment, its ability to work around the clock, its non-contact automatic identification, tracking and management, and its ability to penetrate non-metallic objects for identification and anti-jamming capability. Strong.

With the continuous improvement of living standards, cars began to enter the home in large numbers. In China, the management of vehicles has become a problem. The key issue for effective vehicle management is how to identify the vehicle. Based on the radio frequency identification technology of the access control system, RFID technology applied to the management of access control can effectively realize the rapid and reliable recognition of vehicles, so that security access control management to achieve high efficiency and intelligence.

A: The system hardware constitutes the radio frequency access control system consists of: vehicle-mounted electronic tags, car coil, RF interface, signal processing, control systems and management systems composed of six parts.

1, electronic tag electronic tags, usually also known as transponders. It stores the basic information of the vehicle and the owner, and is installed on the vehicle as a passive tag. When the electronic tag enters the microwave query signal coverage area of ​​the reader, the electronic tag sends the information stored in the chip to the reader through the energy obtained by the induced current, and the effective reading distance is 6-10 m.

2, reader reader includes RF interface and signal processing two modules:

RF interface: It is mainly responsible for sending and receiving signals. It receives command signals from the signal processing and control system, converts the command signal into a microwave signal and sends it out. At the same time, it also receives the microwave reflection signal from the electronic tag and converts the microwave reflection signal into a digital signal to the signal processing module for decoding. deal with.

Signal processing module: It is mainly responsible for the processing of command signals and electronic tag data signals. It receives the command signal from the management system, encodes the command signal and sends it to the radio frequency interface, and converts it from radio frequency interface to microwave signal. At the same time, it also receives the electronic tag data signal from the radio frequency interface and decodes the electronic tag data signal. Send to the management system.

3, management system The management system is mainly responsible for processing user information electronic tag data and control system information. It controls and manages the system according to the user's instructions, receives data from the signal processing module and the control system, sends the command signal to the signal processing module and the control system, and the management system can communicate with the security center through the network.

4. Control system The control system is mainly responsible for the communication control of the gate mechanism. It receives command signals from the management system, controls the gate mechanism, and feeds the gate status back to the management system. That is, if the data read from the electronic tag is analyzed by the management system as a legal passer, the control system signal is given and the gate is opened for release.

5, car sensor coil sense coil selection PBD232 sense loop coil detector. The detector is a vehicle detector based on the principle of electromagnetic induction. Its sensor is a toroidal coil (usually 2m×l.5m) buried under the road surface and having a certain working current. When the vehicle passes through an annular buried coil or stops on an elbow in an annular buried coil, the iron of the vehicle cuts the magnetic flux lines, causing a change in the inductance of the coil circuit. The detector detects the presence of the vehicle by detecting the inductance variation. The detector's response time is lOOms. Its performance characteristics can ensure that the system detects the arrival of the vehicle accurately and quickly, and sends the signal to the computer through the digital I/O card to start the reader.

Two: The system software design software system mainly includes: Reader's signal processing and system management two parts.

Signal processing module software development using C language; system management software using VisualC++ (VC) programming; database using MicrosoftSQLServer2000.

1. The system workflow system is initialized first, and the reader sends an inquiry signal according to a certain time interval and is transmitted by the radio frequency interface module. When the electronic tag enters the microwave inquiring signal coverage area of ​​the human reader, the electronic tag (transponder) receives the inquiring signal and sends its own information in reverse to the reader. After the reader signal processing module receives the serial number, the vehicle carries out the vehicle. Identification. First, anti-collision processing is performed to establish a communication channel, and then the data information is decoded. After decoding, the information is sent to the database for verification. If the check is correct, a signal is sent to the control system; if there is an error, an audible and visual alarm is provided. In this process, if the management system does not send an end command, after the end of a recognition process, the next cycle begins.

2, management software design This system runs on the Pc machine. The application program on the PC can verify the received data according to the communication protocol by collecting the serial port data. If the verification is wrong, the "signal processing module" is required to resend the data; if the verification is correct, the license plate number in the vehicle tag information is extracted and compared with the vehicle information in the database. If the extracted license plate number exists in the database, the information is transmitted to the "control system", the control system is responsible for the operation of the gate (gateway) system, and at the same time, the basic information of the currently-passing vehicle is displayed in the application program interface; if the extracted license plate is If the number does not exist in the database, alert the manager.

The database is the core part of the system. There are three basic forms for storing information. Tables and fields are defined as: Vehicle and owner basic information table: owner's name, owner's ID, owner's unit, vehicle ID number, license plate number, model, car brand, body color, etc.; vehicle traffic record table (space-time information): Vehicle ID number, through the date and time, number of passes, etc.; system operation record table: fault code, failure time.

Third, system function long-distance recognition: Because the recognition distance can reach 10m, and the signal penetration ability of the system is strong, the owners of the vehicle holding the card can enter and exit at a faster speed, and the driver does not have to stop, roll down the window, extend The arm is close to the reader and other operations, greatly improving the efficiency of traffic. Temporary vehicle access is provided by the administrator with a temporary ID card.

Dual card confirmation: This system implements the driver to carry a card. This card can be used for access control. A card is installed on the vehicle. The system recognizes the signal of two cards at the same time before it is released for release. It achieves double insurance.

When the system automatically records the time and place: When the card holder enters or exits, the computer will automatically record the access record and cannot delete the record, which facilitates the query and statistics of various vehicles and personnel entering and exiting the community and the generation of various reports, thereby eliminating errors. Forgery and cheating.

Temporary vehicle automatic billing: After the temporary vehicle reads the card, the fee is automatically calculated according to the time of entry and the charging standard. The special vehicle access is provided by the administrator with a free parking card. The free parking card is specially set and cannot be counterfeited.

In a word, the radio frequency identification technology applied in the access control system can realize the parking of vehicles with effective electronic tags, save time and improve the traffic efficiency of intersections; more importantly, it can monitor the access of vehicles in the community or parking lot in real time. Accurately verify the identity of the vehicle and vehicle owner, maintain regional security, and make the security management of the community or parking lot more user-friendly, informative, intelligent, and highly efficient.