CDMA/GSM双模双待机移动终端射频干扰的研究

本文从GSM手机发射和CDMA手机接收频段相互重叠的实际情况出发,首先分析了双模双待手机的主要干扰来源,即同一手机内GSM发射机对CDMA接收机的干扰.接着分析了CDMA手机在单模工作情况下,接收机正常接收信号时,接收天线输入端信号需要达到的信噪比C/N.然后通过建立双模双待手机干扰模型,利用CDMA方程定量计算了双模双待手机在同频干扰和邻频干扰情况下CDMA天线端接收信号的信噪比,从而说明双模双待手机在技术上需要解决的关键问题.在此基础上分析了CDMA接收机入口处的信噪比符合正常接收条件,提出了解决双模双待手机中GSM发射对CDMA接收干扰的办法,通过实验测试验证了分析结果的正确性.     

一种接收超宽带射频信号的方法研究与仿真分析

在射频接收机的设计中,由于滤波器的带宽和频率源的限制,一般接收机的带宽无法达到几百兆的超带宽范围.设计一种超带宽射频信号的接收方法,通过五路功分和合理选择射频器件,可以在保证信号指标要求的情况下,有效地对250 MHz带宽的射频信号进行接收和下变频.最后通过ADS软件进行射频仿真分析,验证了本接收方法的主要指标满足要求.     

基于GP2015的GPS射频前端电路ADS优化设计

根据“超外差”结构设计了一种以GP2015为核心的GPS射频前端接收电路,混频级数设计为3级,混频输出的中频信号进行多次优化滤波。首先利用ADS2008系统建模和行为级功能仿真验证系统可行性,其次选择合适的低噪声放大器对射频信号进行放大,提高了接收机的接收灵敏度,最后对PCB板的线宽进行阻抗匹配、电路制作及电路滤波优化。测试结果表明,该电路成功地实现了射频信号的下变频及接收,输出信号功率达到-3.3 dBm,镜像抑制能力达到37 dB。     

复杂射频环境下无线接收机电磁兼容

无线接收机是一种能够进行无线电信号接收和解调的电子装备,在图像信息定位和声音信息接收中应用较多,人们生活实践中应用的GPS装置、寻呼机、电视机和收音机等均属于无线接收机。一般情况下无线接收机主要指的是收音机、雷达信号接收机和无线电收报机,组成结构包括功率放大器、前置放大器和调台装置等,对于复杂射频环境下的无线接收机电磁兼容原理等需要从实际分析角度展开研究与分析。     

接收机噪声系数分析

接收机的主要功能是将天线接收到的由目标反射回来的微弱射频信号进行放大、预选、变频、滤波等处理,使目标反射回来的微弱射频信号变成有足够幅度的视频信号或数字信号,以满足信号处理和数据处理的需要.灵敏度表示接收机接收微弱信号的能力,噪声是影响接收机灵敏度的主要因素.分析了接收机链路中主要器件的增益指标对接收机噪声系数的影响,给带宽宽、低噪声、高灵敏度接收机的设计提供借鉴和参考.     

一种外场VHF频段宽带RCS测量接收机设计

基于外场VHF频段目标特性测量需求,设计一种外场VHF频段宽带RCS测量接收机。该接收机采用预选滤波法提高了接收前端选择性,抑制射频干扰信号,同时设计频率关系,实现宽带信号接收,在后续信号处理中采用相参积累法进一步抑制射频干扰及接收机噪声,提高接收机灵敏度,实现大动态范围信号接收。通过外场试验验证,实测结果与理论仿真结果吻合较好,验证了该设计方案的可行性。     

小型移动终端天线设计

分析了适用于手机和数据卡等各种移动终端的小型天线,该类天线主要工作在GSM、CDMA、WCDMA、GPS、DCS、UMTS以及WLAN等小型终端设备的无线通信频段。对小型终端天线的工作原理作了详细分析,并设计了一种典型的三频段平面倒F天线,仿真结果验证了设计方法的有效性。最后对该类小尺寸天线的LC匹配方法进行了研究,可供同类设计进行参考。     

GPS射频干扰浅析

论述信号噪声比和信号噪声密度比的概念，分析了射频干扰(RFI)对GPS接收的影响，最后说明了直接检测RFI的方法以及RFI源的定位。     

飞思卡尔推出新一代射频子系统

电子市场研究公司Forward Concepts表示,WCDMA/UMTS手机市场在2005年增长168%,达到4560万部.为适应高速发展的市场带来的技术需求,飞思卡尔半导体面向手机市场推出四频段GSM/GPRS/EDGE射频(RF)子系统和第四代多模3GWCDMA/EDGE射频子系统.同以前的手机相比,新的射频子系统可将手机的板空间大幅缩小70%,从而为手机制造商提供设计自由度,使他们能够开发出外形小巧而优雅的新款手机.     

基于Matlab的数字中频GPS信号生成模型

精确的GPS信号生成器是测试与评价先进GPS接收机设计的重要分析工具。本文在中频GPS信号理论模型分析的基础上,用Matlab实现了一种数字GPS信号生成模型,它能够在数字中频上产生GPS接收信号,其中包含仿真的噪声和接收机时钟误差。与常规的GPS信号生成器(或模拟器)相比,这种模型设计灵活、易于使用,此外,模型构建涉及对GPS信号在接收机射频前端处理过程的仿真,从而为GPS接收机射频前端的设计提供了支持。     

Taking the challenge of multiple access for third-generationcellular mobile radio systems-a European view

In Europe, the challenge of the design of third-generation cellular mobile radio systems has been taken numerous research and development activities in this field have been started. The authors try to give an overview of the European activities in this field. The article is organized in two parts. In the first part, the requirements for third-generation cellular mobile radio systems such as Universal Mobile Telecommunications System (UMTS) and Future Public Land Mobile Telecommunications System (FPLMTS), which has been named International Mobile Telecommunications after the year 2000 (IMT-2000) are presented concisely. Also, the importance and challenge of the multiple access design for such third-generation cellular mobile radio systems is explained. In the second part, numerous European research activities with focus on the multiple access design for third-generation cellular mobile radio systems are reviewed     

Smart antennas for combined DOA and joint channel estimation intime-slotted CDMA mobile radio systems with joint detection

In cellular mobile radio systems, the directional inhomogeneity of the mobile radio channel can be exploited by smart antennas to increase the spectral efficiency. In this paper, a novel smart antenna concept applying receiver antenna diversity at the uplink receiver is investigated for a time-slotted code-division multiple-access (CDMA) mobile radio air interface termed time-division CDMA (TD-CDMA), which has been selected by the European Telecommunications Standards Institute (ETSI) in January 1998 to form part of the Universal Mobile Telecommunications System (UMTS) air interface standard. First, a combined direction-of-arrival (DOA) and joint channel estimation scheme is presented, which is based on DOA estimation using the Unitary ESPRIT algorithm and maximum likelihood estimation of the channel impulse responses associated with the estimated DOA's, which can also be used as an input for advanced mobile positioning schemes in UMTS. The performance of the combined DOA and joint channel estimation is compared with the conventional channel estimation through simulations in rural and urban propagation environments. Moreover, a novel joint data detection scheme is considered, which explicitly takes into account the signal DOA's and the associated channel impulse responses. The link level performance of a TD-CDMA mobile radio system using these novel schemes is evaluated by Monte Carlo simulations of data transmission, and average bit error rates (BER's) are determined for rural and urban propagation environments. The simulation results indicate that, depending on the propagation environment, the exploitation of the knowledge of the directional inhomogeneity of the mobile radio channel can lead to considerable system performance enhancements     

基于移动平台的脑电波游戏设计与实现

本项目是通过MindWave Mobile与手机终端的结合,设计了意念控制的射击游戏,使用MindWave Mobile耳机作为脑波接收器,通过蓝牙模块传输数据至移动终端,通过在移动终端上的游戏软件接受数据并处理,作为参数用于游戏控制,为玩家提供新鲜体验感用于娱乐的同时,也可用于训练用户的集中度.并且有助于分析人类集中度变化的函数曲线,采集的数据有助于分析人类大脑进行后续研究.并且本项目应实现MindWave Mobile耳机与手机终端的直接连接,而不需通过PC机作为中介平台,可广泛应用于智能移动终端游戏、教育及儿童注意力训练等领域.     

Octa-band internal monopole antenna for mobile phone applications

A low-profile monopole antenna covering the following frequency bands is proposed for mobile phone applications: Global System for Mobile Communications (GSM-900), Digital Communication System (DCS), Personal Communication Services (PCS), Universal Mobile Telecommunications System (UMTS), Wireless Broadband (WiBro), Bluetooth, Satellite-Digital Multimedia Broadcasting (S-DMB), and Wireless Local Area Network (WLAN) frequency bands in the 5.0 GHz range. Multiple resonators in a compact configuration have been used to realise the octa-band internal antenna within a volume of 2.08 cm³ that is very attractive for multifunctional slim handsets. Measured performances of a prototype antenna have been compared to predicted results.     

移动终端的定位跟踪系统研究与实现

定位跟踪技术是指通过特定的定位技术来获取移动手机或终端用户的位置信息(经度、纬度坐标等),并且在电子地图上对跟踪终端的位置进行标注的技术或服务。该系统综合使用了GPS定位技术、WEBGIS、GSM通信网络、GPRS无线分组技术、中间件等技术实现了对移动的终端进行定位跟踪的功能,实现对终端人员的实时跟踪和位置信息的动态管理。移动定位跟踪技术的主要应用场所有以下4种:追踪服务、信息服务、安全服务和付帐服务。     

基于AT89S52与TC35i实现的短信息处理系统

本系统采用嵌入式技术,由单片机AT89S52最小系统与TC35i模块实现GSM基带处理、GSM射频的传输与控制。本文着重阐述短信息接收与发送及终端数据处理的信息流程。短信息接收与发送单元主要由单片机系统对GSM模块实施信息交互控制,终端处理单元完成收、发信息的数据融合与处理。实现单片机控制GSM模块与移动台(手机)信息流的查询与控制,即由单片机控制手机的SMS(Short Message Service)的收发。     

On the use of GPS receivers in railway environments

This paper presents the electromagnetic interference effects on the performance of locomotive onboard Global Positioning System (GPS) receivers due to the railway environment. The evaluation of the maximum tolerated interferences around a train is presented by taking into account European Committee for Electrotechnical Standardization and the International Electrotechnical Commission normative, Mobile Radio for Railway Networks in Europe, and experimental results. These interference levels are used to study the performance of a hardware GPS receiver operating at different modes and considering the possible levels of GPS signal L1 at the earth surface. From the obtained results, it is possible to conclude the reliability of a low-cost GPS receiver for train positioning even if the train equipment has been designed at the threshold of the current normative.     

An efficient integration of GPS and WCDMA radio front-ends

An efficient integration of global positioning system (GPS) and universal mobile telecommunication system (UMTS) radio front-end units is presented. The combined front-end unit includes the transmitter and receiver filters, duplex filter, power amplifier, buck regulator, and power detector for the UMTS wireless code-division multiple-access system. The GPS building blocks of the radio front-end unit consist of the low-noise amplifier and RF filter. The inter-system isolation was experimentally quantified and the compared against the minimum inter-system isolation requirements, defined according to desensitization and intermodulation tests in the GPS receiver. The characterized isolation of the antenna array provided 6 dB of margin over the minimum inter-system isolation requirements for 3-dB degradation of the carrier-to-noise ratio in GPS receivers. The UMTS portion of the radio front-end unit was verified against the Third-Generation Partnership Project standard.     

The Universal Mobile Telecommunication System

The concepts, requirements, and technologies of Europe's third generation mobile communication system-the Universal Mobile Telecommunications System (UMTS)-are discussed. The cellular architecture, radio resource, adaptive resource allocation and handover enabling techniques for realizing an effective UMTS access network are described. The modulation schemes, multiple access methods, and duplexing methods used in the third generation mobile system's flexible radio interface are also described. The architecture, mobility support, and protocol development of the UMTS fixed network are outlined     

基于移动互联网的实时路况系统及其关键技术

基于移动互联网的实时路况采集与发布系统,由运行于智能手机等终端的数据采集客户端软件、基于因特网的实时路况服务器及运行于智能手机等终端的实时路况查询客户端软件3部分组成。其基于智能手机操作系统,利用GPS、A-GPS和GPS数据保障技术,采集交通参与者的位置、速度和方向等信息;利用数据挖掘技术和GIS地图匹配进行数据处理;然后使用位置服务和动态路径规划等技术发布。利用MI-RTTS系统的数据,可发现城市交通问题,据此提出交通工程专业解决方案;缓解城市交通拥堵、节约能源、降低机动车污染排放。