【作者】 于峰；

【导师】 周晓光；

【作者基本信息】 北京邮电大学 ， 检测技术与自动化装置， 2008， 硕士

【摘要】 射频识别(Radio Frequency Identification,RFID)技术是一种利用射频通信实现非接触式自动识别的技术。目前,国内对超高频RFID技术的研究尚处于起步阶段,尤其是基于ISO18000-6标准的915MHz频段的电子标签研究仍属空白。915MHz这一频点在我国恰好处于公共移动通信的频段范围内,目前对该频段的无线研究及应用都已比较成熟,所以,研究ISO18000-6标准的电子标签具有较高的现实意义。本文首先研究了ISO18000-6标准,对其规定的915MHz RFID电子标签的物理接口、协议和命令以及防冲突机制等各方面进行了分析。根据标准的规定,设计了电子标签的系统结构,划分了系统模块,并对天线、射频接口及数字控制等模块进行了电路设计。文中,着重对射频接口模块的电路做了详细设计和EDA仿真,主要包括电源产生电路、复位电路、时钟提取电路、反向散射调制电路和包络检波解调电路等。同时,本文还以Type B类型的电子标签为例,对数字控制部分进行了分析和设计,包括曼彻斯特解码模块、FMO编码模块、CRC数据校验模块、状态机模块、EEPROM模块和防冲突算法实现等。同时,本文还利用Matlab仿真工具对915MHz RFID电子标签进行了系统级仿真。文中,通过SIMULINK通信仿真模型库搭建了仿真模型,在时间域上对发射电路和接收电路进行了系统级仿真,又通过M文件编程实现了电子标签的频域仿真。该仿真不仅从时域和频域两个角度验证了系统设计的完整性和准确性,还直观明了的显示了系统各点的信号情况,供开发设计人员参考。本文所设计的915MHz RFID电子标签,采用了圆形微带天线作为射频前端天线,有较好的电抗特性,适合对功耗和辐射要求比较严格的电子标签使用;对于比较复杂的射频接口电路,则采用相应的芯片模块来实现各部分功能,不仅减少了开发周期和风险,也极大限度地减低了标签芯片的功耗,从理论上来说,能够提高标签的识别距离;在对数字控制电路的设计中,尽量采用简单易编程、且功耗较小的电路实现。同时,本文选用了一款优秀的EDA仿真工具——Multism软件进行电路原理图设计和系统仿真,不仅直观明了地显示出了各部分的信号情况,又有效地减少了整个系统的设计风险。更多还原

【Abstract】 REID(Radio Frequency Identification)is a kind of non-contact and automatic identification communication technology which is realized by radio frequency communication technology.At present,high-frequency and low-frequency technology have been relatively mature in China,but in the field of ultra high frequency,the research work is still in the initial stage,especially for the tag of 915MHZ frequency band based on ISO18000-6 standard. Because 915MHZ frequency band is just in the public mobile communication band,moreover,the study and application are mature,it is deserved to study ISO 18000-6 standard.In this paper,the ISO18000-6 standard has been studied.Its 915MHZ RFID tags physical interface,protocols,commands,and mechanisms for conflict prevention are analyzed.According to the provisions of the standard, designs the structure of tag and the modules of system,and designs the circuits of antennas,radio frequency interfaces,as well as digital control module.The details of circuits of radio frequency interface and EDA simulation are primary contents,which mainly includes power supply circuit,reset circuit,clock extraction circuit,backscatter modulation circuit and demodulation circuit module.Digital control module is also an important component of tag.Here, tag of Type B is introduced,analyzes and designs the digital control part, mostly includes Manchester coding module,FM0 coding module,CRC data check module,state machine module,EEPROM module and conflict prevention algorithm.Furthermore,the system level simulation of 915MHZ RFID tags has been done by use of Matlab.Emissive circuits and receiving circuits have been simulated in time domain through the model which is constructed by SIMULINK communication simulated model library,then realizes the tag’s simulation in frequency domain by M file programming.The integrality and veracity of system have been validated from the time domain and frequency domain.At the same time,the simulation shows intuitively the signals situation of system,which can be referenced by engineers.915MHZ RFID tag designed in this paper uses a circular microstrip antenna as radio frequency front-end antenna,which has preferable reactance characteristics and can be used by tags that have strict requirements on power cost and radiation.For the complex radio frequency interface circuits, corresponding modules should be adapted to realize these functions;In the digital control Circuits design,the simple,easy programming and less power cost circuits are being used.Additionally,the circuit principle diagrams are designed and simulated by an excellent EDA simulation tool called Multism, which displays clearly the signals of every parts of system and reduces effectively the overall system design risk.更多还原