The Design Of RFID Multi-tag Reader In UHF Band

Radio frequency identification(RFID)is a kind of non-contact identificationachieved through wireless communications, and it is a technology with fast speed,high safeness and large information capacity. A RFID system includes: a reader,electronic tags and computer systems, of which the reader is responsible forsending and receiving information, and is the most important part of a RFID sys-tem. RFID systems are divided into: low frequency(LF)system, high frequency(HF) system, ultra-high frequency (UHF) system and microwave system, amongthem, ultra-high frequency band system develops very rapidly in recent years,ultra-high frequency reader has a long-distance identification capability and astrong anti-interference capability.In this paper, the RF technology of RFID systems is summarized, UHF RF-ID development status at home and abroad is analyzed, and starting from theidentification principle of UHF reader, the author makes analysis of the readerchannels, the composition principle of the RF front-end and ISO/IEC18000-6Cagreement. For the RF circuit, the author selects the RF transceiver chip AS3992specialized for UHF internally integrating an ISO/IEC18000-6C agreement,which can directly control the AS3992with a C8051F340MCU microcontroller,and the RF module includes: a clock circuit, a VCO/PLL configuration circuit, aRF transceiver circuit, an isolation circuit, a C8051F340peripheral circuit and soon. An ARM-based control circuit is designed to control the work of RF moduleand carry out communication with the upper computer, and the control module isembedded into the Linux operating system, the author also describes the varioussteps of creating a Linux system software platform, including the establishmentof cross-compiler development environment and the transplantation of systemboot code-vivi. In the software part, the read-write control of C8051F340toAS3992and the ISO/IEC18000-6C protocol implementation are designed, and in the main control circuit, a Qt-based graphical application interface is designed tocontrol the entire reader.An important issue of UHF RFID systems is the implementation of the anti-collision algorithm, in this paper, the ALOHA anti-collision algorithm is adopted,the dynamic frame time slot ALOHA anti-collision algorithm is obtained throughthe analysis of the ALOHA algorithm, and the author carries out a simulation ofthe performance of the algorithm to improve the anti-collision performance of thesystem.