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。     

距离-速度同步干扰环境下的目标检测

针对距离-速度同步干扰,首先基于多普勒滤波器组和恒虚警率（CFAR）检测技术得 到目标检测决策,并结合目标检测决策建立雷达回波的速度-时间数据矩阵。随后分析了目 标和干扰的特征差异,基于超快霍夫变换（VFHT）提取雷达回波的目标特征霍夫空间。最后根 据该霍夫空间采用CFAR检测技术对目标检测,从而形成基于距离-速度同步干扰抑制的目标 检测方法。与常规快速霍夫变换（FHT）相比,提出的VFHT具有更高的计算效率。同时 ,该方法由于在雷达数据处理层面进行目标检测,不需要改变雷达系统的信号处理结构,大 大降低了雷达装备成本。理论仿真表明在同样的目标检测性能前提下,基于VHFT的目标检测 算法所需的信噪比要求放宽了10 dB以上,为弱目标回波信号环境中的应用奠定了基础 。     

超宽带穿墙雷达取样脉冲产生器设计

在超宽带穿墙雷达接收机系统中,其关键的等效采样技术需要一种极窄脉宽高电压的脉冲触发采样门电路来对接收信号进行采样。介绍了超宽带取样脉冲产生技术,讨论并分析了几种常用超宽带脉冲产生方法的特点及其局限性。提出了新型的肖特基二极管脉冲整形网络,设计并实现了应用于等效采样接收机系统的新型亚纳秒取样脉冲产生器,很好地结合了雪崩晶体管与脉冲整形网络的优势,在显著减小脉宽的同时保持了较高的脉冲幅度。通过仿真分析和制作测试,获得了脉冲底宽为400 ps、幅度为6.46 V和波动水平为-14.7 dB的单极性窄脉冲,实测结果与设计数值一致性良好。这种简单高效廉价的电路十分符合超宽带穿墙雷达等效采样接收机取样脉冲的设计。     

用于高动态目标探测雷达的相位编码脉冲压缩技术

为避免多普勒频移对相位编码信号脉冲压缩处理的影响,提出了利用已知脉冲编码序列对回波信号进行逐符号共轭点乘的脉冲压缩方法,将对齐的回波信号转换为单频信号,并利用傅里叶变换实现信号能量的积累。理论分析与计算机仿真表明,多普勒频移对脉冲压缩性能无影响。该方法适合于应用到对高动态目标进行探测的雷达系统中。     

一种S频段高性能频率合成器的设计与实现

设计了一种高性能频率合成器,采用直接数字合成（DDS）与直接模拟合成相结合的方式, 实现了S频段1 Hz细步进 输出,频率捷变时间小于800 ns,并达到杂散抑制优于-65 dBc、相位噪声优于- 115 dBc/Hz偏离载频1 kHz处的高性能指标。     

基于数值拟合的PCMA系统自干扰信号幅度估计算法

针对卫星成对载波复用（PCMA）系统中的自干扰信号,提出基于数值拟合方法的幅度 估计算法,并对其性能进行了分析。该算法适用于非对称和对称PCMA系统,可以有效抵消自 干扰信号与有用信号互相关项不为零引起的误差,并且不会引入相位噪声,更符合工程应用 实际。仿真结果表明,在干信比为12 dB的非对称PCMA系统中,该算法仍能获得较好的 幅度估计精度,信噪比损失始终在0.1 dB左右。     

解析解混沌雷达系统的多目标测距

针对传统混沌雷达对多目标测距困难的问题,提出了一种建立在解析解系统上的混沌雷达多目标测距方法。该方法使用解析解混沌系统中的连续信号作为雷达发射信号,并把解析解混沌系统中的二值离散序列经移位寄存器保存在雷达接收端,通过保存的二值离散序列能够准确重构雷达发射信号模板。使用该模板和回波信号进行匹配滤波,通过匹配滤波输出信号的峰值得到待测目标的距离。该方法能够在-10 dB信噪比条件下实现多目标测距,且雷达接收端因为只需保存二值离散信号所以需要的存储空间小,实现过程成本低廉。仿真实验验证了提出方法的有效性。     

一种毫米波前视合成孔径雷达成像算法

针对传统正侧视和斜视雷达无法对雷达载机前方场景进行成像的缺点,提出了一种基于距离多普勒算法(RDA)的毫米波前视合成孔径雷达(SAR)成像方法。给出了系统的结构模型,分析了系统成像原理。基于空间几何模型和回波信号形式,分析了点目标回波的多普勒历程,给出了方位向多普勒调频率,得到各相位补偿因子和距离徙动校正公式。对成像场景大小和方位向成像分辨率进行了详细分析,采用MATLAB对6个点目标进行了成像仿真,〖JP2〗并对仿真结果中点目标峰值中心的64×64点切片和方位向、距离向进行了分析。理论推导和实验仿真表明,基于RDA的前视合成孔径雷达可以对场景中目标有效成像且方位向成像分辨率可达到2 m,该系统可应用与侦查和制导领域。     

基于三维特征的雷达信号脉内调制识别

针对低信噪比条件下雷达信号识别算法对噪声敏感的问题，提出了一种基于三维特征的雷达信号脉内调制识别算法。该方法通过提取信号的差分近似熵、调和平均分形盒维数和信息维数特征组成三维特征向量，使用遗传算法优化的BP神经网络分类器实现雷达信号的分类识别。仿真结果表明，所提取的三维特征在信噪比为-4~10 dB变化范围内具有较好的类内聚集度和类间分离度，可以实现对不同雷达信号进行识别，证实了该方法的有效性。     

零中频接收机及其AGC方法的研究与实现

实现了基于LT5506下变频器和Cyclone IV FPGA的零中频接收机,采用射频、基 带一体化架构,尺寸仅为8 cm×6 cm×1.5 cm,重量仅为45 g,功耗仅为 800 mW,满足小型化 、低功耗的要求。针对零中频接收机中射频信号检波困难和传统AGC的调节时间受输入信号 幅度影响的缺点,由Cyclone IV完成信号检波,增加对数运算环节并改进环路滤波器的结构 ,配合LT5506中的可变增益放大器仿真并实现固定调节时间的AGC,用8 MHz采样时钟对 1 MHz正弦波进行幅度控制,调节时间恒定为53 μs,不受输入信号幅度影响。     

Universal Coverage, Pinpoint Illustration and Profound Impact HTC 2008 Intermedia Recommendation and Introduction Meeting

Holding 88 percent of train media resources across China, based on "Time Cube", on the 2008 Intermedia Recommendation and Introduction Meeting on December 19, 2007, HTC announced its high-profile strategy of tour marketing and tapping the immeasurable potentials on the train. Meanwhile, HTC officially launched its brand new product Olympic Train on the meeting, providing a fabulous platform for all the brands that are prepared to do a smart marketing on the occasion of 2008 Olympic Games.     

Market presence in China strengthened Network growth and Dual-Chinese-Hub Strategy More frequet Flyer Benefit——Air China and shanhai Airlines Join Star Alliance

In the end of 2007, Air China Limited (hereinafter "Air China") and Shanghai Airlines, formally joined Star Alliance at a ceremony held in the new Terminal Three at Beijing Capital International Airport. With the addition of the two Chinese airlines, Star Alliance now has 19 member carriers operating 17,000 daily flights to 897 destinations in 160 countries.     

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.     

A World of Love 2008 Music Grand Ceremony

Under the guidance of the theme slogan of the 29th Olympic Games - One World One Dream, with dream, love and dedication as its theme, the 2008 Music Grand Ceremony ＆ 1000 People Charity Concert on 100 days cotmtdown to Paralympic Gamesis officiaily launched on December 22, 2007. The 2008 Music Grand Ceremony is sponsored by China Disabled Persons＇ Federation, and co-hosted by National Paralympic Committee of China,     

China''''s National Oil Reserve Center was Born

Aseries of events that occurred in October 2007, are rewriting the history of China's energy industry: November 3 an Energy Law Committee asked the public for suggestions on improvements; forty top experts came together to form the National Energy Expert Advisory Committee on November 6; and the National Oil Reserve Center (NORC)became the nerve centre of oil reserves on November 18. Yet, behind the progress of these recent activities remains the fact that international oil prices still hover around a very high price of US$ 90/barrel, and China's oil imports are close to accounting for half of its total oil reserves.     

MUYANG GROUP

With its headquarters in the historic city of Yangzhou,Jiangsu Muyang Group Co.,Ltd has since its founding in 1967 grown into a well-known group corporation whose activities cover research ＆ development,project design,manufacturing,installation and services in a multitude of industries including feed machinery and engineering,storage engineering,grain machinery and engineering,environmental protection,conveying equipment and automatic control systems.     

2007 China Harbor Ten People

2007 China Harbor Ten People elected the entrepreneurs who contributed a lot to port economy and enterprises this year trough their talent management.These ten people embody their social responsibility,professional skills,creative ability,and charming personality.Bearing full confidence in China＇s port economy,the port entrepreneurs are brave enough to explore a brand new area,so as to promote harbor economic development. At the very beginning of 2008,China Shipping Website,Dalian Maritime University,and China Port and Shipping In- stitute jointly select the 2007 China Harbor Ten People,demonstrate port entrepreneurs＇ stunning minds,disclose their secrets to success,and providing abundant experiences to others in harbor development.The top ten people are various excellence during the ups and downs harbor development.