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。     

高性能L频段频率合成器的改进设计

为了满足航天测控信道的要求,提出了一种高性能L频段频率合成器设计的改进方案,采用PLL+DDS+PLL结构实现了小步进、低杂散、低相噪的信号输出。分析了方案的可行性,设计了样品,并进行了测试,结果显示其相位噪声优于-100 dBc/Hz@10 kHz,杂散优于-75 dBc,但附加的杂散信号导致了系统同频干扰。通过分析找出引起同频干扰的机理,并提出了相应的改进措施。所提方案对测控通信、电子对抗等领域中频率合成器的研发具有一定的参考价值。     

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。     

一种高频谱纯度的C频段宽带频率合成器设计

为了提高频综的频谱纯度，提出了一种新型多级子谐波混频锁相环的设计方法,研制了一款超低相噪频综。介绍了该频综的设计方案，分析了关键技术，仿真和论证了相位噪声和杂散抑制等主要指标，最后对该频综进行了研制和实际测试。测试结果如下：工作频率为4 500~7 600 MHz，频率步进小于1 kHz，相位噪声优于-123 dBc/Hz@25 kHz，频率切换速度小于75 μs，杂散抑制大于70 dB，均满足设计要求，设计方案比较合理可行。采用该方法设计的频综具有小步进、低相噪、换频速度快、低杂散等特点，可用于高性能电子战接收机中，具有广阔的应用前景。     

基于DDS的毫米波汽车防撞雷达扫频源设计

利用直接数字频率合成(DDS)分辨率高、转换速度快的特点,设计了一种基于DDS芯 片AD9910的毫米波汽车防撞雷达扫频信号源。通过DDS芯片产生调频、调幅、调相等各 种调制信号,实现了在短距离内快速捕捉目标、处理信息、发出告警的功能。所 设计的扫频源输出信号中心频率为8.6 GHz,幅度为-16 dBm,相噪为-70 dBc/Hz@ 1 kHz,满 足了在多目标检测时对信号源的幅度、稳定度和相噪的要求,从而使DDS技术得以在微波检 测领域获得应用。     

基于AD9910的频率合成器设计

本文介绍了高性能直接数字频率合成器（DDS）芯片AD9910的特性、内部结构,以及采用AD9910构成了低相噪低杂散的频率合成器,实现了频率、幅度和相位的控制。该频率合成器频率范围66～96MHz,步进1Hz,且在751dHz输出时,相位噪声低于-115dBc／Hz@1kHz。     

基于FPGA的宽动态范围DPSK解调器设计

为了解决大多普勒频移、猝发通信条件下传统接收机结构复杂的问题,设计并实现了一 种基于FPGA实现的宽动态范围全数字DPSK基带接收机。采用1 bit A/D带通采样技术和差分 检测技术,在最大40 kHz多普勒频移条件下实现了70 dB动态范围。该技术已用于 某低成本毫米波数据通信系统中,实现了码速率为10 Mbit/s、动态范围大于70 dB的D PSK信号解调,系统误比特率为10-6。     

B3G射频接收机前端设计

分析了DC-OFDM零中频接收方案,采用两个相邻子载波以分路/合路的方式进行信号处理以降 低硬件难度和复杂度。利用ADS软件设计了B3G射频接收机,其低噪声放大器的最低噪声系数 为1.7 dB,三阶交调点为-1 dBm;下变频器在频带范围内其增益为12.5 dB, 1 dB压缩点-12 dBm,三阶交调点-3 dBm。实验 测试结果表明,所设计的前端满足接收机的指标要求,适合于宽带通信系统。     

一种新颖的捷变频频率合成器设计

提出了一种新颖的直接频率合成器方案,实现了优于3 μs的捷变频指标。采用直接数字频率合成器（DDS ）实现细步进跳频,通过切换混频本振、分段开关滤波、直接倍频方式 拓展输出带宽。分析了关键指标和技术难点,给出了解决措施。该频率合成器实测结果满足指标要求,具 有工程应用价值。     

8 mm脉冲磁控管测云雷达测速多普勒化

8 mm磁控管发射样本中频信号的起始相位随机分布,脉间频率抖动范围为±2 MHz ,脉内频率变化为500 kHz。为了克服这些问题,提出了一种适合于国内第一套毫米波 脉冲 磁控管测云雷达的测速多普勒化算法,幅度信息从回波数字下变频经低通滤波器后直接提取 , 相位信息由零中频回波IQ信号与发射样本IQ信号进行复卷积提取,并算法仿真结果表明多 普 勒频率误差不超过4 Hz。基于FPGA技术实现了测速多普勒化算法,利用高速缓存的设计 思想 实现了复卷器的优化,利用CORDIC算法实现了幅度与相位的高精度提取,并完成了算法在实 际 雷达系统中的测试,雷达的脉冲重复频率为1 000 Hz,多普勒频率在-496～500 H z范围内,雷 达终端显示的速度值与理论值一致;回波信号幅度值为-76～6 dBm,得到的速度值 与理论值 一致。经过该算法处理的地物杂波回波的多普勒速度在零值附近分布,云体目标的回波速度 图清晰可见。该算法已经成功应用于8 mm脉冲磁控管测云雷达系统。     

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.     

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.     

Sony Style in China

Since the normalization of the diplomatic ties between China and ） Japan, the bilateral economic relations have deepened continually. According to the statistic of Japan, China passed U.S. to become Japan＇s top trade partner as well as is the second largest export market for Japan and is the largest import resource for Japan. Japan companies such as Mitsui, Sumitomo, Sony and Panasonic, have set the subsidiaries in China and explored their scales. This year 2008 marks the 30th anniversary of the signing of the ChinaJapan Treaty of Peace and Friendship.     

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.