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针对常规RFID系统对信息控制的不足,提出了一种基于辐射源识别的无源RFID系统的信息监控方法。采集无源RFID标签的辐射射频信号,变换为新的对数谱射频指纹,并进行特征提取与识别,获得标签身份真伪结果;把射频指纹等集成到读写器应用层协议,实现标签与读写器之间信息的控制。建模、仿真与实验表明,对数谱射频指纹仅由标签的频偏与冲击响应决定,具有稳健性等;给出了融合提出指纹的RFID系统挑战——应答认证协议实例。提出方法不仅能增强标签与读写器的认证安全强度,而且能实现通信中标签的身份监控,对于解决密钥泄漏检测公开问题也有一定贡献。 相似文献
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在RFID(射频识别)应用中,读写器(RFIDReader)的任务是控制射频模块向标签发射读取信号,并接收标签的应答,对标签的对象标识信息进行解码,将对象标识信息连带标签上其它相关信息传输到主机以供处理。读写器的作用可谓举足轻重,它的频率决定了RFID系统的工作频段,而其功率直接影响射频识别的距离。根据应用不同,读写器又分为手持式和固定式。RFID给人们带来的最大利益是减少了从事标签扫描工作的人员数量,一般来讲,较多使用的是手持读写器,因为手持读写器更灵活而且比较便宜,例如,Wal-Mart(沃尔玛)主要使用手持式读写器在仓库中寻找货… 相似文献
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UHF RFID读写器在发射大功率射频信号的同时,接收标签返回的微弱信号.UHF RFID通讯特点对频率综合器的频率精度和相位噪声有很高的要求.LMX2531是一款能够满足RFID通讯需要的产品,它采用频率校准电流来提高频率精度,采用自带环路滤波器和控制充电泵电流等措施减少相位噪声.本文描述了基于LMX2531的RFID读写器射频电路,分析了它的功能,详细介绍了如何编程LMX2531工作参数. 相似文献
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在机场、港口、铁路货场、仓库、货柜码头、大型商场等物流中心的RFID(射频识别)标签和读写器无处不在,组成空中的物流跟踪和监管系统.全球正掀起一股RFID热潮,点燃信息技术应用的新亮点,RFID的核心技术是一块集成电路,每块芯片含有RFID数据,读出器可在远距离读取芯片存储的数据,无须在视线距离内作扫描或物理接触. 相似文献
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针对室内无线区域定位的需求,设计了基于有源RFID(Radio Frequency Identification)技术的无线定位系统。RFID读写器和标签系统均采用低功耗MCU芯片PIC16F877A作为核心控制单元,以低功耗无线射频收发器芯片CC2500为核心配合外围滤波器和天线等构成系统的通信单元。在读写器与标签进行数据通信的过程中,通过获取RSSI(Received Signal Strength Indicator,接收信号强度指示)信号推测出读写器与标签之间的距离,在获得来自于多个具有固定位置信息的标签的RSSI信号后,可以实现对读写器的无线定位。实验结果表明,该系统在室内环境中能够实现较高精度的无线区域定位。 相似文献
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To implement an ultra high frequency (UHF) RFID system, the first problem that an enterprise faces is the assurance of stable
and extremely high reading rates. Empirical investigations indicated many hardware and environment factors can affect the
reading rates. Unfortunately, even if all of the hardware and environment factors have been resolved, reading a large number
of RFID tags in a single run is still a challenge. For RFID systems with massive tags, signal collision is the major factor
to reduce system reading rate. To diminish the influence induced by signal collision, this study examined the anti-collision
technology applied in EPCglobal UHF Gen II standards and proposed the method of adapting the Q parameter of control module
in UHF RFID interrogator. Finally, we conducted field simulation to monitor relative reading rates under different conditions
with different tag numbers, speeds passing through portal and Q values. Following by experimental results, this study provided
the criteria to determine optimal Q value by activating system. With proper Q value, stable and extremely high reading rates
in one-time reading of a large number of RFID tags (100 and above) can be achieved. 相似文献
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An electric encoded/optical transmission system of code division multiple access (CDMA) is proposed. It encodes the user signal in electric domain, and transfers the different code slice signals via the different wavelengths of light. This electric domain encoder/decoder is compared with current traditional encoder/decoder. Four-user modula- tion/demodulation optical CDMA (OCDMA) system with rate of 2.5 Gbit/s is simulated, which is based on the optical orthogonal code (OCC) designed in our laboratory. The results show that the structure of electric encoding/optical transmission can encode/decode signal correctly, and can achieve the chip rate equal to the user data rate. It can over- come the rate limitation of electronic bottleneck, and bring some potential applications in the electro-optical OCDMA system. 相似文献
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In order to reduce I/Q imbalance of the full-duplex terminal with direct-conversion transceiver,an algorithm based on self-interference signal was proposed for the estimation and compensation of I/Q imbalance in both transmitter (Tx) and receiver (Rx).Without the perfect transmitter or receiver for I/Q imbalance estimation,the self-interference signal from Tx chain to Rx chain was used for parameter estimation and separation,and the Tx and Rx I/Q imbalance parameters were obtained,respectively.Then the pre-compensation before transmission and the correction after receiving was processed,so that there was nearly no I/Q imbalance in this full-duplex terminal from the view of the other terminals,and the complexity of the signal processing will be reduced as a result of the absent of the I/Q imbalance estimation.The simulation results show that the proposed algorithm can effectively estimate and compensate the I/Q imbalance of the full-duplex Tx & Rx terminal,and improve the overall signal quality and the system performance. 相似文献