共查询到20条相似文献，搜索用时 593 毫秒
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陈兵清 《商情·科学教育家》2013,(38)
本文主要论述了利用FPGA (Field Programmable Gate Array,现场可编程门阵列)进行测频计数,单片机实施控制实现频率计的设计过程.该频率计利用等精度的设计方法,克服了基于传统测频原理的频率计的测量精度随被测信号频率的下降而降低的缺点.等精度的测量方法不但具有较高的测量精度,而且在整个频率区域保持恒定的测试精度. 相似文献
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传统频率计主要以硬件电路为主,测试不同信号频率需要手动切换量程。采用以单片机为核心设计的智能频率计,利用软件自动调整闸门时间,实现量程的自动切换。实际电路测试证明该频率计电路简单、精度较高、工作稳定可靠。 相似文献
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《实验室研究与探索》2017,(7)
为了提高频率计的测量精度和系统性能,解决在传统的频率计中无法实现高低频率等精度测量的情况,采用京微雅格公司的M7系列FPGA,设计了一种基于SOPC技术的等精度多功能频率计。该频率计以内嵌Cortex-M3内核的FPGA芯片为控制核心,通过对FPGA模块和Cortex-M3内核部分的设计,并借助AHB接口的FIFO实现FPGA与Cortex-M3内核之间的数据通信,完成了1Hz~50MHz范围内等精度频率计的设计。通过Model Sim软件仿真和硬件实测表明,该频率计可以完成等精度频率和占空比的测量功能,具有精度高、实时性好等特点。 相似文献
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设计了一种数字频率计,能够测量的频率范围是1HZ-25Mnz,待测信号的波形可以是正弦波、三角波或者方波,幅度范围是O．2V一24V。该设计在高频段应用多周期同步法、在低频段应用周期法来对被测信号的频率进行测量,从而使频率计具有更高的准确度。使用分频芯片,可避免对信号进行预先评估,超出测量范围时会自动提示。 相似文献
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基于TMS320F2812的数字频率计 总被引：3，自引：1，他引：2
采用多周期测量原理,即用标准频率信号填充整数个周期的被测信号,从而消除了被测信号±1的计数误差,其测量精度仅与门控时间和标准频率有关,克服传统的直接测频或者直接测周法均不能全面满足高精度要求的缺陷.选用TMS320F2812型号的DSP芯片作为核心处理单元,结合其高精时钟和快速运算的优点,利用其内部的事件管理器:捕获单元,定时/计数单元,比较单元,脉宽调制电路PWM,实现高精度的频率测量,并实现了脉宽和占空比的测量. 相似文献
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100MHz数字频率计用VHDL语言编程设计,主要由五个模块组成,分别是测频控制信号发生器、十进制计数器、32位锁存器、分频器、动态扫描译码驱动器模块五部分构成.选用分频器将工作时钟分频后,用测频器测频,将被测频率信号经脉冲整形电路后作为计数器的计数脉冲,加入计数器的输入端,测量一定闸门时间内被测信号的脉冲个数,并将其计数值锁存进锁存器中,最后通过动态扫描译码器读出数值,该频率计精度高,可用于频率测量、机械转速测量等领域. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 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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Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
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YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 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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GUO Bao-feng Xiao Da-wei 《重庆大学学报(英文版)》2005,4(3):129-133
Using virtual reality for interactive design gives a designer an intuitive vision of a design and allows the designer to achieve a viable, optimal solution in a timely manner. The article discusses the process of making the Virtual Reality System of the Humble Administrator＇s Garden. Translating building data to the Virtual Reality Modeling Language （VRML） is by far unsatisfactory. This creates a challenge for computer designers to do optimization to meet requirements. Five different approaches to optimize models have been presented in this paper. The other methods are to optimize VRML and to reduce the file size. This is done by keeping polygon counts to a minimum and by applying such techniques as object culling and level-ofdetail switching. 相似文献