中继卫星SMA系统反向链路多波束形成技术

对中继卫星SMA(S频段多址)反向链路多波束形成开环数字波束形成算法（DBF）、3种闭环自 适 应数字波束形成算法进行了分析,通过试验验证了开环波束形成算法和闭环波束自适应 形成算法的可行性。试验结果表明,在飞行器捕获、跟踪的不同阶段,采用开环波束形成与 自 适应波束形成相结合是SMA反向链路波束形成的最优方式。     

跟踪及数据中继卫星系统的正反向通信链路

本文讨论跟踪及数据中继卫星系统的正反向通信链路。包括：１）Ｓ波段多址勤条链路的相控阵天线地面多波束形成自适应对准；２）把ＴＤＲＳ上的３０个单元天线的接收信号转回地面并保证各路之间相对相位，振幅的稳定；３）Ｋｕ波段单址勤务链路中ＴＤＲＳ与用户飞行器天线相互捕获与跟踪；４）扩频－测距码的快捕。     

基于LMS算法的TDRSS自适应多波束形成

跟踪与数据中继卫星系统（TDRSS）是转发地球站对低、中轨航天器的跟踪测控信号和中继从航天器发回地面的信息的卫星通信系统，自适应多波束形成是TDRSS中的一个关键技术。讨论了一种基于中频实数加权的LMS算法的自适应多波束形成方法，采用两路正交实信号进行实数加权，大大节约了硬件资源。理论分析及计算机仿真结果都证明了该算法的可行性及优越性。     

基于SKA1-low的数字波束形成技术

为配合我国参与平方公里射电阵（SKA）项目,深入理解数字波束形成条件下的射电干涉观测和相应数据处理算法,提出了基于多相滤波器组信道化数字移相波束形成和基于分数阶时延滤波器数字波束形成两个技术算法,前者使用互相关法求解相移量来提高波束指向精度,后者是传统算法与射电观测理论的有效结合。首先,详细介绍了算法的理论推导并分析了它们的优缺点;然后,通过仿真实验验证了这两个算法的正确性,仿真结果表明基于多相滤波器组信道化数字移相波束形成算法相比传统算法具有一定的优越性;最后,分析了不同阶数时延滤波器对波束形成的影响并得出了相应结论。这些仿真结果及结论可为从事SKA项目的科研人员提供参考。     

星间链路地面管理设备多阵面相控阵保护机制

多阵面相控阵星间链路管理设备既解决了传统星间链路设备卫星与地面站间精密测量和数传、全球系统的自主导航功能的问题,又缓解了地面星间链路管理设备不能满足“北斗”全球系统部署的困难。分析了多阵面相控阵星间管理设备的特点,讨论了多相控阵同时工作下阵面保护的难题,提出了天线设计与波束管理软件控制两种方法相结合的解决方案。     

一种卫星多波束中的波束选择构架及实现方法

为了以少量卫星载荷设备在广阔的服务区内提供高增益的通信链路，针对多波束通信卫星提出了一种星上收发波束选择的载荷构架及其实现方法。载荷构架分为波束分组与选择模块，实现方法则利用了收发无源设备的频率响应。通过控制前后端有源设备的混频本振，使上行接收波束和下行发射波束能够工作于多波束天线覆盖区内的任意位置。通过波束指向轮循，以低于波束数量的转发器实现了卫星在广大覆盖区内的高增益通信。分析结果表明，相比同样波束规模的多波束卫星，采用所提载荷架构的多波束卫星能够大幅降低载荷重量、功耗及热耗，提高转发器使用效率；相比同样承载规模的多波束卫星，能够大幅提高每个波束的传输性能及整星的吞吐量。     

扩频和高速数据信号的星间天线角跟踪系统设计

分析了中继卫星星间链路低速扩频和高速数据传输信号时,使用单通道单脉冲、有限个系统中频带宽档位、包络检波方法进行角跟踪的可行性,给出了角跟踪误差信号和信噪比计算公式、中频带宽的选取原则.结果表明,该方法适合所有星间链路信号类型的角跟踪,简化了星地控制.     

多波束形成技术研究

讨论了跟踪与数据中继卫星系统 (TDRSS)中关于多波束形成的算法 ,优选的有LMS自适应方式和相位调整自适应方式 ;并简单介绍了波束控制和波束形成的实现     

面阵数字波束形成和对多目标跟踪的研究

用计算机仿真研究面阵天线数字波束形成（DBF）和对多目标跟踪。主要内容包括方阵列天线的方向图、圆阵列天线的方向图、圆阵列天线多目标的跟踪、跟踪前的初始搜索。文中对各种情况下面阵天线的阵因子方向图作了详细的数学分析，建立了相应的模型并进行了计算机仿真。     

波束成形在TD-LTE-A系统中的性能优化

TD-LTE系统中的波束成形（Beam Forming）会受到收、发天线不对称性的影响。TD-LTE-Advanced（TD-LTE-A）系统中使用上行多天线发送可以解决天线不对称性的问题,因此需要对其分析以优化Beam Forming的性能。通过对上行多天线的信道状态信息（CSI）做特征值（SVD）分解,指出了Beam Forming对下行信噪比（SNR）的改善。针对Beam Forming模式下SNR和链路质量指示（CQI）的差异,提出了一种优化链路自适应的方法。数值仿真验证了优化后的TD-LTE-A相比TD-LTE的Beam Forming吞吐率最大提高了24%,其结论对商用TD-LTE网升级到TD-LTE-A具有显著价值。     

Brown＇s Blossom in Britain-China

The overall strategic relationship between U.K. and China is ＂better than ever＂, China- Britain relations have maintained good momentum, with increased high-level exchanges and the reinforcement of strategic mutual trust, with more room for growth in the future.     

Challenge and Opportunity Go Hand in Hand——What Global Economic Agitation Brings to the China's Economy?

Domino effects of the global finance agitation As the origin of the subprime crisis,US financial institutions lost USS45 billion last year,accounted for over half of the total US,EU & Japan loss.Since January 15th,Chtigroup released its financial statement of the 4th quarter,showing a net deficit of USS9.83 billion,which marked the hisoric high of its quarterly deficit.     

Sinosteel：Extraordinary Moves in Industry Chess

Among the Fortune 500 firms,more and more images from China emerge out.On the 2008 list,Sinosteel Corporation,a landmark group of China industries quietly squeezes into the candidate line.As the largest steel service ＆ trade enterprise,its sales reached at RMB 111.24 billion,with a year-on-year increase of 83.03 percent,and the profit grew by 180.03 percent.On the Sinosteel 2008 Work Meeting,the president Huang Tianwen uttered,＂In the coming year,we will work for US$20 billion sales,and look forward to getting a position in Fortune 500 firms for ourselves.＂     

Walk Through Unusual Five Years—— An Exhibitor＇s Canton Fair Course

When the 103rd Canton Fair is approaching, an old friend of Canton Fair, Li Ying from Jiangsu prov-ince recollected his past five years＇ experiences to the grand trade meeting. Each year is special, with some unforgettable memories colored by the year.     

Jean-Pierre Duprieu： Willing to Be A Legate of Sino-French Business

Estaing, former French president, Valery Giscard d＇Estaing attended Sino-French Economic Seminar held in Shanghai in early April and said that the world center has shifted from the west to the east with many European and US companies entering into Asia, and China has the ability to play an important role in the world stage. Estaing, naming himself＂French Confucian＂, then said in Chinese that a cook-group includes 10 people in ancient Chinese soldier system and the cook is in charge of cooking for them. And people who belong to the same cook are actually ＂Partners＂.     

China''''s Stock Market Wave

The annual meeting of the World Economy Forum was held in Davos,a little town in Switzerland,on January 23rd to the 27th this year,with the theme"the Power fo Collaborative Innovation",over 2500 celebrates from ture political and cconomic circles of more than 80 countries and challengred logether to talk about the future of the global economy in 2008,A Forum for the problems and challenges that face whole world,some of the keywords which drew attention during the event were:the U.S.subprime mortgage crisis,soaring energy prices,the economic slowdown in the U.S.ermerging economic bodies,authority funds and the general unpredictable nature of the global economy.     

Trade Promotion from Neighborhood

If you are considering to trade with companies in Japan or expanding your .business to Japan, we are ready to help from the very beginning.＂ You will find this greeting at the first sight on the Chinese website of Japan External Trade Organization （JETRO）. JETRO has committed itself in delivering highly efficient and quality services to meet the demand of internal and external customs including Japanese companies, hence winning a good reputation in the international trade arena. In recent years, with its priority in advancing business cooperation in South and East Asia, JETRO has made great achievement in promoting trade between China and Japan. Therefore, China＇s Foreign Trade interviewed Mr. Yoichi Maine, Deputy Director General of JETRO BEIJING.     

Auto Parts Market Potential Coming into Surface

Looking at the increasingly fierce competition in the world auto market. global automobile manufacturing industry, taking Europe, the U.S. and Japan as representatives, is gradually forming a new type of relationship, mutual cooperation between whole vehicle and parts manufacturers. We can clearly see that auto parts manufacturers have become independent from the whole vehicle manufacturing companies, which means that the former structure of auto industry has greatly changed, and a new relationship,     

Domino Effect on Electricity and Coal Prices

In the middle of last December, the key purchase contracts for coal used in power generation in 2008 were signed, reflecting a demand for more than 1.085 billion tons. It is important to note that the country＇s five biggest power producers, China Huaneng Group, China Guodian Corporation, China Power Investment Corporation, China Huadian Corporation and China Datang Corporation, had settled on the prices on their purchase contracts, and they are expected to consume 290 million tons of coal for generating electricity,     

China's Auto Industry Steps Forward

Last year,the volume of China's auto trade reached US$66.878 bil- lion,of which imports accounted for US$25.982 billion,a year-on- year increase of 24.45 percent;while ex- ports totaled US$40.896 billion,growing by 45.31 percent.The China Association of Automobile Manufacturers(CAAM) predicts that the number of autos sold in 2008 will break the 1 million barrier for the first time in history,representing an increase of about 20 percent.