The Design And Implementation Of Ultra High Frequency Radio Frequency Identification (RFID) Reader

RFID(Radio Frequency Identification)is one of the identification technologies which can realize intercommunication by using wireless channel.In recent years,the application of radio frequency identification systems is more and more.And it has been involved in many aspects of people's daily life.Comparing with Low Frequency RFID systems,the UHF(Ultra High Frequency)RFID system has longer reading distance and faster speed,etc.Nowadays,it has become a hot spot in RFID products.First,the dissertation presented the background of RFID technology and the research status of RFID hardware design technology,then the composition of RFID systems and related principle were presented in the paper,and we presented a scheme of UHF RFID readers which based on the I/Q Modulation/Demodulation technology.Then the hardware design of the UHF RFID reader was introduced in detail,including the circuit design of RF transceiver front-end,analog baseband and digital baseband.The RF part of the reader consists of the frequency synthesizer,I/Q modulator,I/Q demodulation,power amplifier,directional coupler detector,analog baseband and the digital baseband circuits.In additional,a 2.45GHz RF front-end was discussed and implemented in this paper.The digital base-band part is implemented by the embedded systems that embedded ARM9 processor AT91RM9200 is employed as control modules,including the ADCs,data storage systems and automatic power control circuit,and the serial interface and Ethernet Network interface was design for communication with the host computer.In additional,we designed a single chip implemention scheme by the single encoding/decoding chip EM4298.The UHF RFID reader in the dissertation worked on the frequency of 920 MHz～925MHz,with frequency-hopping in 250KHz.The software part of the reader employed the Linux as the operating system,and its function including encoding and decoding of RFID signals,implementation of the automatic power control and configuration of the PLL.After testing,we find the system worked very well and it can be good reading within 6m.