电力线MAC/PHY集成收发器INT51X1及其应用

介绍了美国Intellon公司的电力线MAC/PHY集成收发器INT51X1的功能结构和主要特点 ,介绍了它的引脚功能 ,同时以中压配电网OFDM通信系统的研究开发为例 ,给出了INT51XI的应用实例。     

超声换能器频率特性及匹配研究

超声换能器是一种强非线性时变系统,在不同的工作频率下其阻抗等特性差别很大.在超声换能器的应用中需要对超声换能器进行频率特性分析及阻抗匹配,以达到最高的传输效率和最佳的波形效果.详细分析了超声换能器的频率特性及匹配方式,并对超声换换能器参数进行了测试,根据测试参数设计了阻抗匹配电路.理论分析和实验测试表明,良好的频率及阻抗匹配电路有利于优化超声波发射波形,提高电声转化效率.     

一种锁相式频率合成器的设计

介绍了一种锁相式频率合成器的总体设计和电路结构设计,并进行了实验制作。设计的电路工作频率在１００ＭＨｚ以上,可广泛应用于雷达,航空,航天,通讯,导航,锁相环路等领域。     

Secure Communications System Through Concurrent AJ and LPD Evaluation

In this paper, a systematic approach and their corresponding metrics for concurrent anti-jamming (AJ) and low probability of detection (LPD) performance evaluations of a secure communications system are investigated. In general, it is necessary to deal simultaneously with adversary threats of both active jamming and passive detection for a secure communications system concern. For independent or concurrent AJ and LPD performance evaluations, a single varying paired and multiple paired fixed collocated jammers/interceptors scenario is explored with real sinc type (sin(x)/x) antenna patterns being considered for the communicators. The error probability with both AJ and LPD being considered simultaneously can be derived as system- and geometry-dependent factors and categorized as system metrics related to jammers, interceptors, and communicators themselves only. Whenever multiple collocated jammers/interceptors are considered, we can observe interesting “smoothed” effects for bit energy to jamming density ratio (E _b /J _o ), when one of these varying jammers/interceptors is approaching or receding. In addition, by means of these system metrics, it is intuitive and straightforward to enhance system performance for the victim or to deteriorate system performance for the adversary, respectively. Moreover, the proposed approach and metrics have also paved one practical way for the developments of the latest emphasized cognitive radio (CR) communications systems, if all the collocated jammers/interceptors on the proposed scenario are replaced with “cooperative” communicators.

感知无线传感网中能量检测的判决门限设定

The Internet of Things (IoT) is called the world’s third wave of the information industry. As the core technology of IoT, Cognitive Radio Sensor Networks (CRSN) technology can improve spectrum utilization efficiency and lay a solid foundation for large-scale application of IoT. Reliable spectrum sensing is a crucial task of the CR. For energy detection, threshold will determine the probability of detection (P_d) and the probability of false  alarm P_f at the same time. While the threshold increases, P_d and P_f will both decrease. In this paper we focus on the maximum of the difference of P_d and P_f, and try to find out how to determine the threshold with this precondition. Simulation results show that the proposed method can effectively approach the ideal optimal result.     

手持式超高频RFID读写器天线设计技术综述

天线作为手持式超高频射频识别技术(Radio frequency identification technology,RFID)读写器中的关键部件,其性能直接影响到RFID系统的读写距离和读写器体积大小.论文分析研究各种手持式超高频RFID读写器天线的设计技术,重点介绍应用最广的微带天线设计方法、技巧及发展趋势.     

硅衬底上射频无源低通滤波器的设计及版图实现

文章系统地研究了微波无源低通滤波器的设计原理及其设计方法。根据网络综合法，设计出了一个—3dB截止频率为1．2GHz的2阶低通无源滤波器，其器件参数C1、L1、C2分别为2．56pF、13．252nH和2．56pF。采用自行设计的算法，编制了相应的Matlab程序，计算出滤波嚣的版图结构参数。最后，用ADS软件对该滤波器进行了版图级的模拟验证。结果表明，该微波无源滤波器的散射参数曲线与理想元件所组成的滤波器的散射曲线相吻合，且性能好，能够满足实际应用的需要。     

基于ModBus通信协议的变频控制系统设计

由于变频控制系统多工作于高电压、高温度的环境中,对变频装置的稳定性和抗干扰性都要有很高的要求。鉴于ModBus总线可靠的数据传输、快速的响应和强大的抗干扰能力,文中主要介绍了ModBus协议RTU传输模式的基本内容,设计了基于ModBus RTU的变频控制系统,替代继电器组成的控制回路。通信采用RS485总线标准,串口通信采用查询方式接收和发送数据.开发控制器和变频器之间通信连接程序.从而提高变频器抗干扰性和稳定性。     

多峰I—V特性的共振隧穿量子器件

讨论了电子对双势垒共振隧穿的现象和特性,较为详细地论述了近年来发展起来的具有多峰I—V特性的共振隧穿量子器件的原理、结构和电路应用,最后展望了这类器件的发展前景。     

一种基于EPF滤波的三维单站无源定位算法研究

利用频率变化率、方位角及俯仰角信息,提出一种对固定辐射源的三维单站无源定位算法。该方法通过质点运动学原理,得出目标辐射源的位置,之后采用EPF滤波算法进行处理,对粗略定位结果进行修正和平滑,逐步估计出目标的位置。EPF（ExtendedParticleFilter）滤波是将EKF（ExtendedKalmanFilter）算法作为重要性函数的一种粒子滤波方法。仿真结果表明,基于EPF滤波的单站无源定位算法比传统的EKF滤波算法收敛更快、更稳定,滤波效果更好,定位精度更高,这对无源定位跟踪算法精度的提高和实际应用有很大的意义。