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。     

Public Financial Expenditure——A Reflection of the Livelihood Improvement

In recent years.China's public finance put social construction high on the agenda and attaches more importance on livelihood insurance and improvement.The 2003-2007 public financial expenditure reflects a fact that the government isputting more emphasis on livelihood andissues concerning the people.     

Voices from the MPC and CPPCC

"Crucial for economic growth.energy utilization has its role in all economic sectors and every aspect of people's daily life.Now we are in dire need of a new profession,namely energy manager.We not only need to have passion and responsibility,but also a scientific approach to conserve energy and cut emissions.APpropriate legislation should be in place.and a special profession should be introduced to ensure the implementation of these laws and regulations."     

Slowdown Trade Surplus Growth

According to Ma Kai＇s economic planning report submitted to the NPC session on March 5th,（Ma Kai is the Minister in charge of the National Development and Reform Commission）,the government has listed the slowdown in trade surplus growth and the steady expansion of external investment as major tasks for 2008.     

Ouyang Riping： A Hero Besides Entrepreneur

A bout fifty years ago. a baby＇s cry broke the sky of quietness, in a small and beautiful town of Hunan province, which surroundcd by green hills and clear water. Though his .birth brought his family great happiness and hope just as any new life, nobody knew that the little boy would get great achievement when he grow up. even start his business oversea, and earn international honor. Let＇s share with you the entrepreneur Ouyang Riping＇s story, which may insights thcsc people who want to succeed and complete oneself in favorite condition or adversity rather leave things to so-called fate.     

Belarus, A Chinese Fort in Europe

＂In recent years, we＇ve found increasing interest from Chinese investors in the Belarus economy. Please let China know, Belarus is always ready to be a true friend to China. We have built a fort in Europe for China,＂ the President of Belarus, Alexander Lukashenko told Zhou Xiaochuan, President of the Bank of China, during his visit to the capital of Minsk, on January 8th, he expressed his high praise and firm confidence in the development of Sino-Belarusian relations.     

What＇s Behind Spring Festival？

Similar to what the Christmas Day means for the westerners,the Spring Festival is the most important celebration for Chinese people.This big event according to Chinese traditional lunar calendar relaxes and pleases the whole country as the happiest gathering time of the year.National-wide crusade for going back home,too-difficult-to-get train tickets,generous family-going-out shopping,Miaohui laundering,New Year Eve reunion dinner,visiting friends and relatives,watching annual TV gala......each piece of clue reminds us of the smell of Chinese Spring Festival.     

KEY WDRDS for Foreign Investment in China

FDI(Foreign Direct Investment),a component of a country's national financlal accounts,is investment of foreign assets into domestic structures,equipment,and organizations.It does not include foreign investment into the stock markets,concession and subcontract.FDI iS thought to be more useful to a country than investments in the equity of its companies because equity investments are potentially "hot money"which can leave at the first sign of trouble,whereas FDI is durable and generally useful whether things go well or badly.     

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.     

Consumption, New Protagonist in 2007 GDP

Not long ago, the National Bureau of Statistics released its 2007 Macro Economy Index. Social consumption retail sales reached RMB 8.9 billion, increased by 16.8 percent over the previous year, or 3.1 percentage points higher; the whole investment in social fixed assets was valued RMB 13.7 billion, a year-on-year increase of 24.8 percent, that is 0.9 percentage points higher; and trade surplus amounted to RMB 24.7 billion, rising by 47.7 percent compared with the same period last year, 26.3 percentage points falling over the increasing speed last year. According to preliminary estimates, GDP for the year was RMB 24.67 trillion, up by 11.4 percent from the previous year,