Research On The Key Technology Of Baseband Unit Of UHF RFID Reader

RFID (Radio Frequency Identification) is a kind of rising automatic identification technology, which combines multidisciplinary technologies, such as electronic technology, communication technology and computer technology. It utilizes radio frequency signals and spatial coupling (electromagnetic field or an alternating magnetic field) to carry out non-contact and two-way data communications, target identification and data capture. In recent years, RFID technology is developing rapidly, and it has been applied in production, logistics, retail, transportation and many other fields.In the RFID system, the reader is one of the most basic components. It is responsible for connecting front-end information carriers (ie, tag) and back-end applications (running on the computer). The reader consists mainly of RF frond-end, baseband unit and control module. The baseband unit is between RF frond-end and control module. It is responsible for completion data encoding, data decoding and cyclic redundancy check, etc. It is one of the key technologies of UHF RFID reader. Therefore, the research on the baseband unit has important significance.Firstly, this thesis introduces the basic principles of RFID system briefly and analyzes the communication protocol deeply. Secondly, the overall structure of baseband unit is designed basing on the ISO/IEC 18000-6 Type B communication protocol. Finally, the key modules of baseband unit are analyzed and designed from both hardware and software aspects respectively.In terms of hardware, test platform of baseband unit was built. Using EP1C6Q240I7, which is a FPGA manufactured by Altera corporation, as the main chip, the author designed hardware circuits, including power supply circuits, clock circuits, AS (Active Serial) configuration circuits, JTAG debug circuits, and RS232 interface circuits, and finally succeeded in producing the printed circuit board, soldering components, debugging circuits.In terms of software, using hardware description language, top-down design method, and modularizing design principle, the author designed the key modules of baseband unit, including the UART interface module between baseband unit and control module, the Manchester encoding module from reader to tag, the FMO decoding module from tag to reader, and the CRC module. The timing simulation results show that the circuit is correct. In the Cyclic Redundancy Check module, the author improved the existing serial CRC circuit, proposed a parallel CRC check method, and realized it.