| RFID(Radio Frequency Identification) is one of the identification technologies which can realize intercommunication using wireless channel. In recent years, the application area of RFID system has greatly increased and been involved in many aspects of people's daily life. Comparing with 13.56MHz RFID system, 915MHz RFID system has the advantages of longer reading distance and faster speed etc. It has currently become a hot spot in RFID products.A 915MHz RFID system is designed. The system structure and working principle of RFID system are discussed. The physical mechanism of RFID system working at the frequency of 915MHz is elaborated. The thesis selects Anti-collision algorithm and Encryption Scheme by analyzing and comparing some kinds of Anti-collision algorithms and Encryption Schemes.In the terms of hardware design, AT89S52 is selected as the main controller, thus constituting main control, keying reset, serial communication circuits etc. Melexis's TH72032 is adopted to realize RF transmitter modules and Melexis's TH71112 to realize RF receiver modules. The baseband transmission rate is up to 40 kbps.For the software design, it follows the principle of modularization and structured programming. The programming language is C in MCU. The Software is consisted of main program, serial communication program, read/write sub-module program, low-level operational procedures and conflicts-prevention program etc. Serial communication program functions as communicating with the host computer. Read/write sub-module program is responsible for the tag read and write. Low-level operational procedures are involved in Manchester and FMO's coding and decoding. Lastly, the design of the application program is introduced combining with the security access control system of Residential Quarters.This system in this paper has features of modularization, high reliability and low-cost. The test results show that it meets the standard requirements and has values of application and popularization. |
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