超短波跳频电台的自适应数据传输

介绍了超短波跳频电台点对点数据传输的通信系统模型,在此基础上重点讨论了链路控制层协议,提出并实现了一种高效的自适应变速和自适应变帧长的组合ARQ数据传输方案,线路实验表明,该方案具有很高的数据传输效率.     

Improving Radio Frequency Transmission Properties of Graphene via Carrier Concentration Control toward High Frequency Transmission Line Applications

Graphene has been gradually studied as a high‐frequency transmission line material owing to high carrier mobility with frequency independence up to a few THz. However, the graphene‐based transmission lines have poor conductivity due to their low carrier concentration. Here, it is observed that the radio frequency (RF) transmission performance could be severely hampered by the defect‐induced scattering, even though the carrier concentration is increased. As a possible solution, the deposition of the amorphous carbon on the graphene is studied in the high‐frequency region up to 110 GHz. The DC resistance is reduced by as much as 60%, and the RF transmission property is also enhanced by 3 dB. Also, the amorphous carbon covered graphene shows stable performance under a harsh environment. These results prove that the carrier concentration control is an effective and a facile method to improve the transmission performance of graphene. It opens up the possibilities of using graphene as interconnects in the ultrahigh‐frequency region.     

感应无线数据通信中同频干扰抑制

工业现场电气设备产生的与通信载波频率相同或相近的噪声干扰(简称同频干扰),严重地制约了感应无线数据通信的应用发展。提出了采用双传输线与单接收天线同间距交叉的感应无线数据通信同频干扰抑制技术,通过原理阐述和实验分析,表明该技术能够有效地抑制同频干扰噪声,提高信噪比。     

无线电的传输

在对大直径超长钢管、钢棒的无损检测中,用多通道旋转探头来采集信号,用滑环来传送信号,由于滑环同时又要传送磁化电流,这就给传送的可靠性带来了问题。在分析了基于滑环传送方式中所存在问题的基础上,提出了基于软件无线电的缺陷信号传输方式,将磁化电流和缺陷信号分开传送,经实践验证该方法能有效解决原系统中存在的缺陷,并且传送信号的准确度有了很大的提高。     

Analysis of Radio Frequency Transmission along a Trolley Wire in a Mine Tunnel

An idealized model of a trolley wire communication system in a tunnel is considered. To facilitate the analysis the tunnel cross section is taken to be semicircular and the surrounding rock medium is homogeneous with a finite conductivity. The metallic rails or other conductors on the flat floor of the tunnel are represented by a plane metallic reflecting surface of infinite extent. The trolley wire and associated feeder line are assumed to be equivalent to a single cylindrical conductor that is parallel to the axis of the tunnel but located anywhere within the cross section. The appropriate modal equation is then solved for the propagation constant of the dominant mode. It is shown that the attenuation rate increases significantly as the trolley wire approaches the tunnel wall. However, even when the trolley wire is within 20 cm (8 in) of the wall, the attenuation rate at 200 kHz is still less than 2 dB per kilometer.     

基于光学倍乘法产生光毫米波的全双工毫米波光纤传输系统设计

毫米波光纤(ROF)传输系统中当采用强度调制器直接调制毫米波信号时,随着传播距离的延长会产生信号强度的周期性衰落问题,限制了毫米波通信技术的发展.光学倍乘法(OFM)将低频或中频调制信号搭载在扫频光信号上,通过在基站生成毫米波的方法,有效缓解信号强度的周期性衰落,具有广阔的发展前景.提出并实验研究了一种基于光学倍乘法产生光毫米波的全双工毫米波光纤传输系统.系统中利用光纤Bragg光栅提取光波作为上行链路光载波,基站中不需配置光源,而且对光功率的损耗小,合理利用了资源.基站中还采用低频本振与毫米波载波混频的方法实现上行链路本振,解决了上行链路本振的生成难题,方法简单,成本低廉,有利于简化基站,降低成本.     

中频软件无线电接收机中信号传输和处理技术

文章首先构建了基于软件无线电理论的中频接收机实验平台,重点介绍了DMA结合McBSP的数据双向传输技术,DSP/BIOS设置管理应用程序中工作对象McBSP和DMA,并安排工作线程的调度。     

Analysis of Radio Frequency Transmission in a Semicircular Mine Tunnel Containing Two Axial Conductors

We present an analysis of the propagation in a uniform tunnel of semicircular cross section that contains two axial conductors. In particular, we show that, even if one of these conductors has high ohmic loss, one of the two propagating modes has relatively low attenuation. This corresponds to the situation where an unloaded dedicated wire is used to improve radio frequency communication in a mine tunnel that contains a heavily loaded trolley wire.     

高频微波PCB基材

本文详细介绍了高频微波电路板(树脂)基材的三个性能指标(介质常数、介电损耗、基材厚度)对高频微波电路板的特性阻抗、Q值等方面的影响;在此基础上归纳出未来高频微波基板的发展及研究方向.     

Radio Frequency Pulsewidth Modulation

The width of a train of square pulses can be varied to produce a modulated carrier at the pulse repetition frequency. When the pulse train is generated by switching (class D) transistors, highefficiency operation is possible. The efficiency of this type of amplifier can be significantly higher than that of conventional pulsewidth modulation amplifiers, since the switching rate is reduced. In addition, the spectrum of a bipolar pulse train so modulated has the highly desirable property of all spurious products being band limited near the odd harmonics of the carrier.     

光载无线通信系统传送60GHz毫米波无线信号

随着无线通信业务的发展越来越快,人们对无线通信带宽的需求也越来越高。目前主要的无线技术标准最高也只能提供Mbps的速率,已经不能满足无线技术发展需求。为了满足人们对无线通信带宽的需求,同时应对低频频谱即将耗尽的难题,本文将光载无线通信和60GHz毫米波的优势相结合,提出一个适合传送60GHz毫米波的光载无线通信系统,为以后的无线通信的系统结构提供参考。     

无线射频识别(RFID)技术

RFID是Radio Frequency Identification的缩写,即无线射频识别。它是集计算机技术、信息采集处理技术、无线数据传输技术、网络数据通信技术和机械电子自动控制技术等多学科综合应用为一体的自动化控制系统。最初用于无法使用条形码跟踪的特殊工业场合,后来多利用它来定位、确认及跟踪库存产品或其他目标。其实,目前备受各方关注的RFID并不是一项新的技术,早在二战时它就被美军用于战争中识别自己和盟军的飞机。     

GSM无线网的频率规划

频率规划是GSM中非常重要的一个环节,它会直接影响到无线通信服务的容量和质量。在频率规划中的频率复用和利用率的规划又取决于站点的好坏。一个好的站点会使频率的复用度得到最大,提高整体的频率资源利用率,提高网络的容量和保证的网络的质量。频率的复用要考虑BCCH和TCH层的特性,规划出不同的复用模式。频率复用的模式取决于频率资源的多寡和最大配置的设计,而基站的最大配置又取决于网络的频率复用模式,两者息息相关。     

无线电频率管理概述

本文从无线电频率及其管理的基本概念出发,以无线电频率资源的合理配置及使用技术为着眼点,结合对实际工作的亲身体验,对无线频率资源管理现状和存在问题进行了表述,并针对问题提出了一些建议。     

Improved Coded Mark Inversion for the Passive Radio Frequency Transmission System of the Electronic Time Fuze

To fit the limited volume and power consumption of the passive radio frequency transmission system of the electronic time fuze, an improved coded mark inversion (CMI) is proposed in this letter. From the performance analysis, the energy transmission efficiency of this encoding method is at least 50% higher than that of CMI and NRZ. Finally, the experiment results show that by adopting this improved CMI, the change of DC voltage through magnetic coupling is lower than 0.2 V when the accuracy of data transmission is above 99.5%.     

面向射频隐身的组网雷达多目标跟踪下射频辐射资源优化分配算法

针对组网雷达系统多目标跟踪场景,该文提出一种面向射频(RF)隐身的组网雷达射频辐射资源优化分配算法。首先,采用目标跟踪误差的贝叶斯克拉美-罗下界(BCRLB)作为目标跟踪性能指标。其次,以各雷达照射目标的驻留时间资源和辐射功率资源加权和为优化目标,以BCRLB不大于给定目标跟踪精度阈值及系统射频辐射资源作为约束条件,建立了包含雷达节点分配方式、驻留时间和辐射功率3个优化变量的优化模型。然后,采用两步分解法对上述优化模型进行了求解,即先固定雷达节点选择,利用内点法对简化后的非凸非线性优化模型进行求解,之后再通过匈牙利算法确定最佳雷达节点分配方式。仿真结果表明,相较于辐射资源均匀分配算法,所提算法可以有效降低组网雷达的射频资源消耗,提升系统射频隐身性能。     

面向射频隐身的组网雷达多目标跟踪下射频辐射资源优化分配算法

针对组网雷达系统多目标跟踪场景,该文提出一种面向射频(RF)隐身的组网雷达射频辐射资源优化分配算法.首先,采用目标跟踪误差的贝叶斯克拉美-罗下界(BCRLB)作为目标跟踪性能指标.其次,以各雷达照射目标的驻留时间资源和辐射功率资源加权和为优化目标,以BCRLB不大于给定目标跟踪精度阈值及系统射频辐射资源作为约束条件,建立了包含雷达节点分配方式、驻留时间和辐射功率3个优化变量的优化模型.然后,采用两步分解法对上述优化模型进行了求解,即先固定雷达节点选择,利用内点法对简化后的非凸非线性优化模型进行求解,之后再通过匈牙利算法确定最佳雷达节点分配方式.仿真结果表明,相较于辐射资源均匀分配算法,所提算法可以有效降低组网雷达的射频资源消耗,提升系统射频隐身性能.     

载频稳定度在射频指纹识别中的应用研究

射频指纹识别是利用辐射源射频特征唯一性对其个体身份进行识别的技术,具有广阔的军民用应用前景。针对传统射频指纹特征稳定度不高、难以工程实现的问题,提出了一种基于辐射源频率偏移和相位噪声等多维频域特性的射频指纹识别方法。该方法以ADS-B信号为例,利用统计原理对频率偏移和相位噪声特征进行量化处理,并利用贝叶斯分类方法对信号进行分类以实现辐射源个体身份的识别。通过半实物生成和实采ADS-B信号数据两种方式对提出的算法进行实验验证。实验结果表明,该方法能够对同型号的辐射源进行有效区分,对真实环境下4个目标的识别正确率达到93.5%。     

射频已调波同步技术在单频网中的应用探讨

本文首先分析同步广播单频网的常见技术问题,阐述传统基带同步方式与射频同步方式的不同特点,随后对射频已调波技术理论做简要介绍,最后对基于射频已调波方式的同步广播单频组网方法进行探讨.     

无线射频识别中间件技术

无线射频识别（RFID）技术及其应用,近年来在国内外的发展方兴未艾。中间件是构建以及部署RFID系统时所必须的功能组件,被称为RFID系统的“神经中枢”。中间件实现标签数据的处理和上报,内部处理流程由清点规则的状态跃迁机制实现。作为一个软件系统,中间件的架构应用了面向对象的思想、参考了设计模式的成功经验。融合网络设备管理功能、支持多标签标准、支持多厂家阅读器等将是中间件的技术发展方向。