船载卫通站天线极化面控制改进设计

极化面调整是船载卫通站天线跟踪线极化卫星实现极化匹配必备的基本功能，而船载卫通站穿越赤道后极化面需反转180°，传统的设计会由此引起通信中断。通过对赤道附近区域设备工作状态与位置特点的分析，从扩大极化面机械转动范围与优化极化控制程序两方面进行改进，利用天线馈源中波导的轴对称性，有效推迟了穿越赤道后极化面反转的时机。理论计算与实际应用测试表明，对于某船常用的航线与卫星，改进后的系统可将穿越赤道后极化面反转的时机推迟6.8 h以上，有效解决了卫通站穿越赤道时出现的通信中断问题。     

E&C跟踪对极化角的影响及解决方法

针对船载卫通站使用线极化卫星通信过程中出现的反极化信号干扰问题,根据不同 状态下信号电平变化,发现干扰信号强度与天线跟踪角度有关。结合天线采用的三轴稳定体 制结构特点,建立天线转动几何模型,通过不同跟踪模式下天线角度的比较,对其相互关系 进行了分析,推导出了该体制下极化角计算公式,据此进行极化补偿,有效解决了EC模式下 跟踪线极化卫星出现的极化隔离度下降问题,并对由此引起的极化限位问题采取了应对措施 。应用结果表明,分析正确,方法可行,可为其它卫通站解决类似问题提供参考。     

船载卫通天线角度调整模式存在问题的分析与改进

通过分析目前船载卫通站伺服系统常用的角度调整模式,指出各种角度调整模式均 忽略了因地点位置变化及特殊条件下对天线跟踪的影响,提出通过实时计算理论大地角为基 础的复合调整模式的设计方案。该方案消除了高俯仰角状态以及地理位置变化对跟踪的影响 ,解决了过顶跟踪带来的不利因素,使船载卫通设备满足全方位、无盲区跟踪,确保了通信 畅通。     

基于MDBZP 的C/A码信号高灵敏捕获算法

卫星信号的捕获是GPS接收机信号处理的首要任务。针对在微弱信号的情况下传统捕获方法不能很好地捕获到卫星信号的问题,提出一种改进的二倍分组块补零（MDBZP）方法为高灵敏度GPS接收机提供理论依据。该方法将连续相干积分分解成普通循环相关和随后的傅里叶变换来产生不同的多普勒频移搜索,并针对连续积分跨越多个导航电文数据位的情况给出解决方案,同时考虑了多普勒效应对码长造成的影响。仿真结果表明,此方法对低至15dB-Hz的微弱信号C/A码信号仍有较好的捕获能力。最后给出了不同载噪比情况下所对应的检测信噪比。     

和差极化方式不同导致跟踪问题的分析

船载卫通站在不同海域跟踪B极化信标出现了相位渐变的现象,根据双通道接收机跟踪原理 进行公式推导,证明当和差通道极化方式不一致时,和差通道受环境和极化角影响导致的相 位变化是反向的,此时即使跟踪的是圆极化信标,极化角的变化也会导致相位变化。     

车辆自动定位及监控报警系统（GPS－C~3A）

车辆自动定位及监控报警系统（ＧＰＳ－Ｃ~３Ａ）中国华诚集团华诚卫通公司在目前广泛使用的全球卫星定位系统（ＧＰＳ）及移动通信网技术基础上研究开发了一种车辆自动定位及监控报警系统ＧＰＳ－Ｃ￣３Ａ。它集ＧＰＳ技术、移动通信技术、数据通信技术、数据处理及计算?..     

多元外辐射源单站时差定位技术

针对传统单站无法实现时差定位、多站定位布站选址困难的情况,提出了一种利用多元外辐射源实现单站时差定位的方法,并推导了定位算法和详细流程。基于几何精度因子（GDOP）方法分析了不同时差测量精度、基线长度、布站方式对定位精度的影响。利用Monte-Carlo仿真验证了定位算法的有效性,也说明了这种利用多元外辐射源定位新思路的可行性。仿真结果表明,该定位方法在长基线、Y型布站时定位精度最高,相比均采用地面外辐射源定位,利用卫星与地面外辐射源结合的方式可以使三维定位精度提高10倍以上。     

基于LEON3开源软核的卫星导航接收机设计

为了提高卫星导航接收机的工作性能以及小型化设计,在现场可编程门阵列（FPGA）平台上开发一款基于LEON3开源软核的拥有自主知识产权的卫星导航接收机。通过LEON3开源软核架构和自主设计的分段匹配滤波器(PMF)与快速傅里叶变换(FFT)相结合的捕获模块、基于延迟锁定环的码跟踪环路和基于科斯塔斯环的载波跟踪环路相结合的跟踪模块IP核实现卫星导航接收机的基带系统级芯片（SoC）设计,最后完成接收机系统的软件设计并在DE2-115 FPGA平台上对接收机系统进行验证测试。实验结果表明所设计的接收机性能优良,能够正常捕获并且跟踪到卫星信号,定位结果显示正常,误差在3 m左右。拥有完全的硬件软件源代码以及优良的性能使得所设计的接收机对国内导航的发展有着重要意义。     

厘米级“北斗”相对定位的试验验证

随着我国“北斗”卫星导航系统的发展,“北斗”精密相对定位的应用市场日益拓展。在动态对动态环境中,将基准站与移动站分别设在不同的车辆载体上,验证了“北斗”实时动态相对定位的精度。平台跑车和省道跑车结果显示水平相对定位误差和天向相对定位误差都在厘米级,表明“北斗”系统性能完全满足高精度应用的需求,能替代相应应用领域的全球定位系统（GPS）。     

直播卫星接收问题及解决方案

直播卫星接收在阿拉善盟地区定位安装、技术维护时所遇到问题及解决方案。     

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,     

Slimmed May Day Holiday

Last November the State Council of China decided to renew its holiday system by reducing the seven-day May Day holiday to three days and introducing three new one-day public holidays, namely the Qingming Festival, Dragon Boat Festival and Moon Festival. By doing so, the three golden-week holidays that were introduced in 1999, namely the Spring Festival, May Day and National Day, could be better distributed.