一种低时间旁瓣电平,高多普勒容限的脉压信号波形综合及其处理方法

本文针对某雷达的要求，寻到了一种时间旁瓣电平低、多普勒容限高的脉冲压缩信号－截断高斯窗非线性调频（ＮＬＦＭ）信号，介绍了此信号波形的综合方法，为进一步提高脉压性能，给出了修正型匹配滤波处理方法，并给出了此种信号在小脉压比时经匹配滤波和修正型匹配滤波处理后脉压性能的计算机仿真结果。     

一种线性调频信号超低旁瓣脉冲压缩方法

雷达脉冲压缩希望具有超低距离旁瓣的特征,线性调频信号采用加窗方式可达到约-35 dB的距离旁瓣电平。基于超低旁瓣电平信号设计方法,在不考虑信噪比损失条件下,提出了一种新的超低旁瓣的脉冲压缩方法,基本思想是针对给定线性调频信号,频率滤波权值采用超低频旁瓣频域信号与线性调频信号频域的比值,可以将接收端旁瓣电平输出最低到-120 dB。同时,从理论上和数值结果中分析了信噪比损失、延迟敏感性等问题。     

利用双正交小波变换优化G3-PLC系统性能

为了提高G3-PLC(G3-Power Line Communication)在复杂信道环境下通信的可靠性，提出了基于双正交小波变换的正交频分复用（Discrete Wavelet Transform-Orthogonal Frequency Division Multiplexing,DWT-OFDM）。通过双正交小波变换减小复杂信道环境下G3-PLC通信系统中OFDM载波间干扰，并通过合理减少循环前缀，优化传输效率，降低峰均比。在DWT-OFDM的G3-PLC系统中，通过不同小波基性能分析与对比，利用bior6.8双正交小波基进行系统性能优化。将DWT-OFDM的G3-PLC系统在实际电力线噪声库环境下进行实验分析，仿真结果表明，在平均误码率为10-3量级时，性能有5 dB左右提升，通信效率由40%提高至54%；结合限幅法，峰均比由11 dB降低至8 dB，通信性能极大优于基于FFT-OFDM的G3-PLC系统。     

一种稳健的混合范数约束的波束综合算法

在阵列信号处理中为抑制噪声和干扰,一般都要求波束有比较低的旁瓣和零陷,同时,需要具有良好的稳健性。为此,提出了一种新的混合范数约束的波束综合算法。该算法运用稀疏表示方法,对波束的主瓣和旁瓣分别使用不同的范数约束,同时对波束的零点和敏感度因子进行约束,用MATLAB(Matrix Laboratory)的凸优化工具包进行求解。仿真实验表明,设计得到的波束具有更低的旁瓣和零陷,最高旁瓣电平约为-28 dB,而最低零陷深度可达-50 dB;算法求解过程简单,与现有算法相比能够容忍较大的幅相误差,具有良好的稳健性;同时,阵列效率与经典算法相比提高了8 dB左右。     

基于平滑RAT的多相码信号参数估计

针对Radon-ambiguity变换（RAT）在估计多相码信号（Frank码、P1、P2、P3、P4码）调制参数时受噪声影响严重的问题,提出了基于平滑Radon变换的多相码信号参数估计方法。首先理论上分析了噪声影响多相码信号RAT估计性能的原因,进而通过二次平滑估计出信号RAT的噪声基底包络,最后在去除噪声基底的RAT平面中完成多相码信号调制参数的估计。仿真实验表明,该方法调频率和码元宽度估计的信噪比门限相比传统RAT方法分别降低了1 dB和4 dB。     

基于循环自相关的正弦调频信号参数估计新方法

为解决现有的正弦调频（SFM）信号参数估计方法运算复杂度高、受信噪比限制等问 题,提出了一种基于循环自相关的SFM信号参数估计新方法。首先分析了SFM信号循环自相关 函数特征,推导了信号调制频率的估计表达式;然后对信号延时相乘以去除其正弦调制特性, 得到单频信号并估计信号载频。最后,利用信号频率调制的周期性,对下变频至零频的信号 进行周期累加以减少噪声影响,通过对累加后的信号进行瞬时频率计算得到调制指数估计值 。仿真表明,信噪比（SNR）大于6 dB时,各参数估计值的均方根误差小于-18 dB 。该算法计算量较小,为同等条件下利用卡森准则（CR）方法的16%,便于工程实现。     

一种基于经验模态分解的信噪比盲估计新算法

为了增强未知样式信号的信噪比估计性能,提出了一种基于经验模态分解（EMD） 的信号信噪比估计新算法,通过固有模态函数（IMF）分量平均周期判断信号与噪声界限。 给出了经验模态分解估计法的工作原理和流程图,分析了经验模态分解估计法的性能。仿真 结果表明,与信号空间分解法一样,经验模态分解估计法能够实现盲信号信噪比估计,后者 估计均方误差比前者要小,在0 dB信噪比下均方误差不超过0.3 dB。     

新型靶场全空域全数字相控阵测控系统设计

针对后续靶场多发齐射等新型试验任务的测控保障需求，提出了基于全空域覆盖多频段综合孔径天线阵列、分布式数据采集与传输、多功能通用“资源池”为基础的新一代靶场多功能综合测控系统。针对靶场遥测常用的S频段和安控常用的P频段，给出了双频段共阵面全空域覆盖相控阵的具体实现方式，并仿真分析了核心指标。仿真结果表明，全空域增益波动在1 dB内，第一副瓣电平均小于-13.0 dB。此外，该系统架构具有可扩展性。     

一种雷达频率源的简易设计方法

针对传统多功能雷达频率源方案复杂、体积大、成本高的缺点,提出了一种雷达频率源的简易设计方法。该方法基于高频主振分频的频率合成方案,并通过信号频率的组合设计进一步简化了电路形式,成功实现了某型雷达所需的线性调频激励源、捷变频本振源、多普勒模拟源、采样时钟等多路信号的输出,X频段信号相位噪声达-106 dBc/Hz@1 kHz和-114 dBc/Hz@10 kHz,跳频时间小于2 ??s,性能指标与采用直接频率合成实现的雷达频率源相当。     

一种基于频移滤波器的混合信号盲恢复算法

针对单天线接收的频谱混叠的混合信号盲恢复问题,在频移滤波器结 构上,提出了一种基于相关函数误差准则的自适应频移滤波信号盲恢复算法。该算法利用滤 波 器输出信号和参考信号以及混合信号与参考信号之间的相关函数误差来调整自适应滤波器输 出权值。分析了该算法的稳态性能。仿真结果表明：在信噪比大于-5 dB的条 件下, 该算法对混合信号分量的恢复相似度达80%以上,并且该算法仅需已知混合信号分量的循环 频率,无需其它先验信息,具有计算量小、敛速度快的优点。     

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,