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射频功率放大器的特性会随信道切换、环境温度、工作状态等多种因素发生变化,为了保证功率放大器的优良工作特性,具有自适应性能的预失真系统就显得非常重要。提出了一种自适应反馈检测方法,以减小放大器输出信号的幅度失真和相位失真作为系统自适应的优化目标,〖JP2〗采用多方向搜索优化算法对预失真系统进行优化调整,使系统始终处于最优工作状态。研制了工作于Ka频段10 W自适应射频预失真线性化固态功放原理样机,当工作温度为-40℃~+60℃时,在3 GHz的工作带宽内,三阶交调指标优于-32 dBc。测试结果表明该功放具有工作频带宽、温度适应性广等特点。 相似文献
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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。 相似文献
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讨论了基于离散信号空间上的最小能量(小波)框架的跟踪干扰信号识别和去噪算法。利用一组框架对采用相位调制的接收信号进行分解,如果受到跟踪干扰,则未干扰区信号和干扰区信号的3个分解子信号将呈现明显不同的能量分布特征,据此提出了一种跟踪干扰信号识别和自适应阈值去噪算法。理论分析和仿真结果表明,识别算法具备低虚警率和漏警率性能,而去噪算法有效抑制了干扰信号能量,10-2 误包率时,BPSK+1/2 Turbo信号中1/16尾部信号受到干信比值10 dB的高斯噪声干扰后,去噪算法获得了约4 dB的增益;而QPSK+1/2 Turbo信号中1/8尾部信号受到干信比值10 dB的高斯噪声干扰后,去噪算法可以把误包率性能从1降低至约0.67的水平。 相似文献
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基于信号特征进行模式识别的调制识别方法需要先计算信号的高阶特征、高阶累积量再进行模式识别,整体设计复杂,特征不易计算。机器学习技术由于其强大的特征提取能力和分类能力,被广泛应用到模式识别领域中。针对调制识别问题,提出了一种基于欠完备自编码器的调制识别技术,使用欠完备自编码器进行调制信号的特征自动提取,再使用神经网络分类器进行分类识别。整体模型更为简洁,运算复杂度较低,有利于部署在硬件上进行实时识别。对常见的BPSK、QPSK、2ASK、2FSK、16QAM数字调制方式进行的识别实验表明,算法在信噪比10 dB时平均识别率高于0.97,并且在信噪比为0 dB时仍然有0.92以上的平均识别率。 相似文献
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旋转映射信号将编码比特旋转移位后映射为符号,同时采用了隐性交织、加扰等技术,具有交织复杂度低、信道效率高等特点,是一种典型且使用较为广泛的短波通信信号。针对第三方接收条件下,频率选择性衰落造成该类信号难以有效接收的问题,推导了该类信号的软符号解映射、映射方法,提出了一种针对该类信号的多天线联合Turbo均衡算法,实现了软信息在均衡与译码之间的迭代交换。典型短波信道下的仿真结果表明,迭代4次后的两天线联合Turbo均衡在10-5误码率时相对两天线硬判决译码提供了约4 dB的增益,相对两天线软判决译码提供了约1 dB的增益,在10-4误码率时相对单天线Turbo均衡提供了约5.5 dB的增益。 相似文献
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The central bank of China has raised her deposit rate for 6 times,and deposit reserve rate for 16 times,since last year up to now,which resulted to a great suffer to those small and medium sized enterprises in finance collection.30 percent of China s small and medium sized enterprises have to be closed down, and 60 percent of them are because of finance problem.How to gather the fund is the biggest obstacle for China's enterprises to grow. 相似文献
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《中国对外贸易(英文版)》2008,(9)
Contribution to the society
Zhang Hao owns great opportunity to store intelligence and knowledge, in her early year.Zhang Hao was graduated from Economic Management Department of People's University in 1983 and later finished her study in Advanced Training Program of CEO of Chinese Direct Selling Enterprises in Peking University. 相似文献
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《中国对外贸易(英文版)》2008,(6)
From the very beginning of the dumpling incident,China has pav great concernontheoroblem and moved rapidly to find the reason and take further actions.Series of investigations carried in both countries by co-organized experts'team received a primary fruit as the true picture of the incident.Each time,China IS sparing no effort responsibly to solve the products quality dilemma,which other countries face in the same. 相似文献
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Li Zhen 《中国对外贸易(英文版)》2008,(14)
Beijing‘s new financial dream On May 5,the Beijing Municipal Government released a notice regarding its plans to spur the financial industry, vowing to put forth a strong effort to become the national financial decision- making center,financial management center and financial information and ser- vices center,and formally announcing its ambitious aspiration to become a financial hub with international influence. 相似文献
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Holding percent of train media resources across China based on "Time Cube" on the Intermedia Recommendation Introduction Meeting on December HTC announced its high-profile strategy of tour marketing 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 Olympic Games.…… 《中国对外贸易(英文版)》2008,(1):58
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. 相似文献
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Audrey Guo 《中国对外贸易(英文版)》2008,(1)
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. 相似文献
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《中国对外贸易(英文版)》2008,(12):52-55
Qindao is the host city for several events of the 2008 Olympics, including the sailing competitions which will take place along the shoreline by the city. The unique architecture combination of German and Chinese in the city centre, the German demographic roots and a large Korean expat population, give Qingdao a distinct atmosphere. Too many eye-ball catching strengths turn the beautiful seashore city into an attractive place in foreign investor's eyes. 相似文献
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Li Yinghong 《中国对外贸易(英文版)》2008,(12):57-59
Asia Society is the leading global organization working to .strengthen relationship and promote understanding among the people, leaders, and institutions of Asia and the U.S. Every year the Society presents a high-profile Corporate Conference in a selected city in Asia to examine the implications of macroeconomic trends and geopolitical developments for the region and the world. It provides a leading forum for executives to meet the policymakers and business leaders who shape the Asia Pacific business environment. 相似文献
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Mr.Abdullah Yusuf Secretary General/Chairman Central Board Of Revenue of Pakistan arrived Shenzhen on April to meet with Mr.Sheng Guangzu the Chinese Minister for Customs Administration for discussing the bilateral customs issues.During his two-day visit China's Foreign Trade Magazine interviewed to Mr.Abdullah Yusuf in Beijing he gave the high evaluation on this visit China's great development in the recent years.…… 《中国对外贸易(英文版)》2008,(10):57-57
Mr. Abdullah Yusuf, Secretary General/Chairman, Central Board of Revenue of Pakistart, arrived Shenzhen on April 22 to meet with Mr. Sheng Guangzu, the Chinese Minister for Customs Administration for discussing the bilateral customs issues. During his two-day visit, China's Foreign Trade Magazine interviewed to Mr. Abdullah Yusuf in Beijing, he gave the high evaluation on this visit and China's great development in the recent years. 相似文献
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Audrey Guo 《中国对外贸易(英文版)》2008,(10):56-57
On the occasion of the 10th panniversary of diplomatic relations between China and South Africa in 2008, China is celebrating "South Africa Week" to commemorate. H.E. Dr. Nkosazana Dlamini Zuma, the minister of South Africa, 相似文献