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971.
Dragos Nicolae Vizireanu 《International Journal of Electronics》2013,100(11):1175-1181
The principles for the development of portable instrumentation equipment (multimeters, frequency meters, etc.) using quantised sine signals, with a common unknown fixed frequency, and an estimation algorithm implemented on digital signal processors (DSPs) are described. An unknown internal sine signal is generated. For measurements, analog to digital converters (ADCs) acquire multiple samples of sine signals, which are quantised and transmitted to the DSP. A precise quantised sine signal, with a common unknown fixed frequency, signal estimation algorithm, for DSP-based instrumentation, is presented. An iterative process is performed to obtain amplitudes, phases, dc components, common frequency and to control the ADC number of bits. Final solutions depend on the initial values, obtained using different classical estimation algorithms. The accuracy of the initial values of iterations and the number of used points have a large influence on the speed of convergence. The algorithm stops when quantisation conditions are satisfied. 相似文献
972.
F. Nasim 《International Journal of Electronics》2013,100(9):1228-1239
We have employed technology computer-aided design – a Synopsys® tool to carry out a comparative study of the electrical behaviour of the metal–insulator–semiconductor Schottky diodes with different metal contacts (Ag, Au, Pt and Cr), on n-Si(100). We employed physics models to determine the Shockley–Read–Hall (SRH) and Auger recombination rates as a function of electric field profile in the depletion region. An insight was obtained as variation in the electric field at the metal–semiconductor interface due to work function variation affected the current mechanisms and recombination rates. The results were compared with the existing models. On the basis of analysis, merits and demerits of Schottky junctions formed due to these metals are discussed. The ideality factor of Au and Pt was found to be just around 2.0, while it was higher for Cr and Ag. However, the barrier height in the case of Cr was small, thus making it another possible metal layer for the Schottky contact. Similarly, SRH recombination rates were almost negligible for Au and Pt metal layer and became appreciable for Cr and much higher in Ag, making it not a good choice for the Schottky contact. 相似文献
973.
In many signal processing situations, the desired (ideal) magnitude response of the filter is a rational function:
(a digital integrator). The requirements of a linear phase response and guaranteed stable performance limit the design to a finite impulse response (FIR) structure. In many applications we require the FIR filter to yield a highly accurate magnitude response for a narrow band of frequencies with maximal flatness at an arbitrary frequency
0 in the spectrum (0, ). No techniques for meeting such requirements with respect to approximation of
are known in the literature. This paper suggests a design by which the linear phase magnitude response
can be approximated by an FIR configuration giving a maximally flat (in the Butterworth sense) response at an arbitrary frequency 0, 0<0<*. A technique to compute exact weights for the design has also been given. 相似文献
974.
Stina Svensson Gunilla Borgefors Ingela Nystrm 《Journal of Visual Communication and Image Representation》1999,10(4):379
In many applications thinning of objects is of great interest. We here present a skeletonization algorithm that is based on the idea of iteratively thinning the distance transform of an object layer by layer until either an anchor-point is reached or the connectivity breaks. Our algorithm is general in the sense that any metric and any connectivity can be used. Also, it is based on ideas that are not specific for 2D. The properties of the resulting skeletons are evaluated according to the “Lee–Lam–Suen properties.” 相似文献
975.
以雷达电子战系统仿真与评估为应用背景,基于信号级建模仿真方法和通用化、模块化设计思想,构建了适用于多种雷达电子战系统仿真应用的通用雷达杂波仿真系统,介绍了系统的设计与实现方法,给出了其中的关键仿真模型。该系统能够对固定平台和运动平台下雷达所接收的地/海杂波以及气象杂波进行信号级模拟。最后给出了仿真结果,验证了该系统的有效性。 相似文献
976.
977.
978.
979.
基于数字水印的证件防伪技术 总被引:5,自引:0,他引:5
证件防伪是人们广泛关注的社会问题。本文提出了一种基于数字水印的证件防伪技术方案。该方案将水印嵌入到证件持有人的数字照片中,通过对数字照片边界的RADON变换来矫正图像在打印扫描(简称PS)过程中引入的几何失真,以证件号码为种子,产生具有良好自相关特性的随机序列作为水印信号,为提高水印的鲁棒性,采用强度自适应的DCT系数局部调整法,将水印重复多次嵌入到图像的分块DCT中频系数中。水印的提取采用相似度检测法,无需原始的图像。实验结果证明了该方案的可行性和有效性。与其他防伪技术相比,基于数字水印的证件防伪技术具有隐蔽性好,保密性强,技术容易更新,无需特殊材料和工艺,成本较低等突出的优点。 相似文献
980.
提出了一种特殊米波雷达体制下的多目标检测方法。该方法借助数字波束形成(DBF)、脉冲多普勒(PD)和单脉冲技术在空域、时域、频域内完成目标测量。文中给出了系统框图、检测算法和仿真结果 相似文献