Uhf Rfid Reader Design

Radio Frequency Identification (RFID) technology which communicates through wireless signal was used for identifying enemy's airplane by American army in The Second World War and has been developed since 1980s. Comparing with other contact identification technology, the RFID has great advantages in distance, environment and data capacity. With the development of integrate circuit and requirement of society, RFID has been developing quickly.In this dissertation, the basic principle, structure, working frequency, standard and actual conditions of RFID technology are researched, and international standard ISO/IEC 18000-6B which was used in physical distribution widely is analyzed. On the basis of the work above, central targets are finished as followed:(1) The application characteristic and requirement of UHF RFID in tobacco physical distribution has been grasped;(2) In order to resolve that the collision occurs when many tags transmit data at the same time, many anti-collision algorithm used in RFID has been researched, such as ALOHA and Binary tree. A new dynamic framed slotted ALOHA (DFSA) algorithm which the probability of collision and expected value of tags in one slot is used to decide the number of slots in next frame is put forward;(3) The wireless radio frequency transceiver has been researched and simulated: Based on the requirement of tobacco physical distribution, the transmission, receiving and capture of wireless signal has been researched. Several structures of wireless receiver have been compared. A part of radio frequency circuit has been simulated;(4) The specimen machine of UHF RFID reader according with ISO/IEC 18000-6B has been designed. In the hardware design, the ARM7 controller LPC2378 which is the production of NXP is used as main controller, multi-channel homodyne receiver structure and switch modulate ASK RF transmitter have been used. The system software uses top-down analysis procedure and divides the program into several modules, such as the selection of working, transmit and receive, coding, decoding and protocol execution etc. The random binary tree algorithm is used as anti-collision algorithm.