共查询到20条相似文献,搜索用时 78 毫秒
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采用基于DDS模块的硬件实现方法设计基带信号发生器,在FPGA内部用DDS模块进行频率合成和叠加,利用EDA技术和FPGA实现直接数字频率综合器DDS的设计。可以完成快速的频率切换,并且在改变时能够保持相位的连续,很容易实现频率、相位和幅度的数控调制。实验结果表明该信号发生器达到了一个比较好的设计精度。 相似文献
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采用基于DDS模块的硬件实现方法设计基带信号发生器,在FPGA内部用DDS模块进行频率合成和叠加,利用EDA技术和FPGA实现直接数字频率综合器DDS的设计.可以完成快速的频率切换,并且在改变时能够保持相位的连续,很容易实现频率、相位和幅度的数控调制.实验结果表明该信号发生器达到了一个比较好的设计精度. 相似文献
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介绍了一种基于FPGA的DDS波形发生器设计方法,并从DDS原理、FPGA系统设计进行了分析.通过实验测试表明采用该设计方法的波形发生器输出的波形具有平滑、稳定度高、频率稳定度和相位连续等众多优点,在工程应用上具有一定的实际意义. 相似文献
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介绍直接数字频率合成器(DDS)技术的工作原理,提出了一种基于单片FPGA的DDS波形发生器的设计方案,分析各模块的设计思路,通过VHDL及LPM宏模块完成各模块电路设计,并在Quartus Ⅱ软件Signal TapⅡ进行测试,能够产生频率和相位可调的正弦波、三角波、方波、锯齿波等多种波形. 相似文献
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陈国童 《赤峰学院学报(自然科学版)》2014,(4):42-44
本文提出了一种新型相位可调的低频信号源设计方法.采用DDS(Direct Digital Synthesis)技术产生数字式移相正弦波信号.信号生成由CPLD实现,主要包括相位累加器和波形查找表.以单片机为控制芯片,产生频率控制字和相位控制字传送给CPLD,可大幅减轻对单片机速度的要求. 相似文献
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廖建庆 《洛阳师范学院学报》2014,(2):29-32
介绍一种相位可调的信号发生器的实现方法.利用直接数字合成技术(DDS)产生数字式移相正弦波信号.信号生成由CPLD实现,主要包括相位累加器和波形查找表.以单片机为控制芯片,产生频率控制字和相位控制字送给CPLD,从而可以大幅减轻对单片机速度的要求. 相似文献
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王利众 《黔南民族师范学院学报》2006,26(3):12-13
直接数字式频率合成技术(DDS)是一种先进的全数字频率合成技术,本文基于DDS的相位调制功能,给出了一种DDS数字移相器的设计方案. 相似文献
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DDS多波形信号发生器的设计与实现 总被引:2,自引:0,他引:2
详细介绍了直接数字频率合成器(DDS)的工作原理、基本结构.在参考大量DDS相关文献的基础上,提出了符合结构的DDS设计方案,利用DDS技术设计了一种高频率精度的多波形信号发生器,此设计基于可编程逻辑器件FPGA,采用Max+PlusⅡ开发平台,由Verilog_HDL编程实现. 相似文献
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基于FPGA的信号发生器的设计 总被引:4,自引:2,他引:2
贺敬凯 《深圳信息职业技术学院学报》2008,6(2):63-66
简要介绍了直接数字频率合成(DDS)的组成及其工作原理,给出了基于Ahera公司的FPGA实现多波形信号发生器的设计过程和电路结构。设计在QuartusII软件中完成,并给出了仿真波形。该设计用FPGA实现,因此有许多优点。比如:在不修改硬件电路的情况下频率可调,波形可以选择正弦、三角等多种波形,且电路结构简单、扩展性好,具有频率范围宽、频率分辨率高、相位连续、切换速度快等优点。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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Rajesh Kanoi 《海外英语》2007,(1):52
Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer. 相似文献