数字化宽带测向系统中的概率解模糊算法

为了进一步提高干涉仪的测向精度,增强对宽带信号的适应能力和扩展系统的工作频率范围 ,以实现数字化宽带测向系统,提出了概率解模糊模型和基于最大后验概率的快速算法。仿 真结果表明,该算法解模糊速度快,解模糊能力强,误解模糊概率低,可广泛运用于干涉仪 等需要解相位差模糊的领域。     

基于相关比幅测向的圆阵干涉仪解模糊算法

针对比幅测向精度较低而干涉仪测向相位易模糊这一问题,提出了一种基于多波束比幅测向的圆阵相关干涉仪解模糊改进算法,实现对小型无人机方位的快速估计。首先,根据目标无人机的图传信号特征值建立离线数据库,利用改进的多波束相关比幅法对无人机来波方向进行粗略测量,通过二次插值法对“栅栏效应”造成的估计偏差进行一定修正;然后,将修正后的角度测量值对干涉仪实测相位差进行解模糊;最后,利用无模糊的相位差通过相关运算实现来波方向的精确估计。该算法将相关运算运用在比幅测向中,有效提高了干涉仪解模糊概率。与传统的比幅测向法和干涉仪测向法相比,该算法只需3组天线就能完成测向功能,其测向精度提高至2°以内,并且该算法对天线一致性要求低,实时性高,可实际应用于圆形阵列测向体制,实现对无人机的快速测向。     

海事卫星上行信号测向的工程实现

结合海事卫星信号的信号特征,以相关干涉仪测向算法为基础,提出了一种海事卫星上行信号测向的工程实现方法,在一片FPGA中完成数字下变频、FFT实时运算、相位差计算等复杂运算,在一片DSP中完成相关干涉仪方位计算。与以往的方法相比,该方法解决了对海事卫星上行信号测向的问题,频率分辨率被提高到5.7 kHz;通过降低相位差的波动度和插值提高了方位的稳定度和精度;采取在DSP中完成方位计算的方式减少了FPGA器件数量。最后,试验结果验证了所提方案的实用性。     

鉴相方法的分析与比较

简要介绍了干涉仪测向中模拟和数字两种相位差测量方法,重点对这两种方法的测向误差进行了分析,最后对鉴相方法进行了比较。     

数字化宽带测向系统中天线阵列基线设计

为了进一步提高干涉仪的测向精度,增强对宽带信号的适应能力和扩展系统的工作频 率范围,论述了在工作频率范围和测向精度约 束下如何设置天线阵列基线的问题,得到了系统测向不模糊的条件和测向角的最优线性无偏 估计（BLUE）解。仿真实例表明,该结论正确,并可以指导数字化宽带测向系统整体设计和 优化。     

一种稀疏重构的相关干涉仪测向算法

针对基于凸优化模型的相关干涉仪测向算法计算量过大的问题,提出了一种基于稀疏度自适应匹配追踪算法的相关干涉仪测向算法。该算法首先根据压缩感知原理利用传统相关干涉仪算法的测向数据库作为基底将入射信号稀疏表示;接着,根据贪婪算法对信号进行重构,估计入射信号的方位。该算法的优点在于在迭代过程中引入回溯思想,自动调整估计步长,实现计算复杂度和估计精度的平衡。仿真结果表明,相比基于凸优化模型的相关算法,该算法的计算量大大降低,测向速度提升24.6%,特别在多入射信号情况下具有明显优势。     

一种多脉冲联合处理的塔康辐射源定位方法

根据塔康（TACAN）脉冲序列的连续性，提出了一种基于多脉冲联合测向定位的新方法。该方法仅需两个相距较远的天线阵元，先利用塔康脉冲的特征，建立单个脉冲和多个脉冲间对应的侦测平台、目标飞机以及塔康信标台三者位置关系方程，得到目标方位初始解；利用该初始解，对两阵元干涉仪测向解模糊，得到方位角的高精度解，再代入时差-方位双曲线方程得到目标位置的高精度解。该方法相比传统方法有更高的测向定位精度和更简化的天线布局，有利于工程应用推广。     

负SNR数字调相信号的干涉仪测向技术

传统意义上的干涉仪测向数学模型与处理流程一般要求目标信号具有正信噪比（SNR）,在对负SNR调制信号实施测向时通常会产生较大误差甚至失效。在分析传统方法失效原因的基础上,利用数字调相信号的特点,通过非线性变换对负SNR信号进行高次载波恢复,然后针对恢复后的高次载波进行相位差提取,从而获得被测信号的来波方向。在此基础上对该方法所能达到的精度进行了理论分析,并将其推广至凡是具有可恢复载波分量的测向应用情况。仿真结果验证了该方法的有效性,这对于干涉仪在电子侦察和电磁频谱监测中更加广泛的应用提供了新的参考。     

一种基于统计分析的解定位模糊方法

针对相位测量定位系统是否正确解辐射源位置模糊的判别问题,提出了基于相位差拟合误差均值与方差假设检验的统计判断方法,以逐步剔除错误解;对于剩余的正确辐射源位置估计,给出了提高定位精度的统计处理方法和辐射源位置估计的置信椭圆。仿真试验结果表明,提出的解模糊方法能有效降低将错误解判别为正确解的误判比例,定位结果的统计处理方法可以提升定位精度并缩小置信椭圆。所提方法对于促进相位干涉仪系统的实际应用具有积极意义。     

高速宽带通信信号测向处理模块的设计与实现

针对紧凑型的宽带高速通信信号侦察测向应用需求,对相关干涉仪测向处理模块进行 合理的采样率设计和算法优化,利用FPGA运算能力强的特点,在有限的硬件资源中实现了 60 MHz带宽的准实时测向处理,对提高侦察跳频等低截获概率信号的效能有重要意义。     

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.