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41.
Improved partial response maximum likelihood method combining modulation code for signal waveform modulation multi-level disc 下载免费PDF全文
In this paper, we describe an improved adaptive partial response maximum likelihood (PRML) method combining modulation code tbr signal waveform modulation multi-level disc. This improved adaptive PRML method employs partial response equalizer and adaptive viterbi detector combining modulation code. Compared with the traditional adaptive PRML detector, the improved PRML detector additionally employs illogical sequence detector and corrector. Illogical sequence detector and corrector can aw)id the appearance of illogical sequences effectively, which do not follow the law of modulation code for signal waveform modulation multi-level disc, and obtain the correct sequences. We implement the improved PRML detector using a DSP and an FPGA chip. The experimental results show good performance. The higher efficient and lower complexity can be obtained by using the improved PRML method than by using the previous PRML method. Meanwhile, resource utilization of the improved PRML detector is not changed, but the bit error rate (BER) is reduced by more than 20%. 相似文献
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全波形反演利用全部的波场信息做反演求解,兼顾了地震波的运动学特征和动力学特征,是一种直接基于波动方程描述地震波在地下介质中的传播过程,能够获得地质结构和岩性资料的方法.但是作为一种非线性反演算法,如何提高全波形反演的计算速度和成像精度是目前优化反演的难点和重点.针对全波形反演的效率问题,采用分层和模块化的matlab工具箱,开展了基于随机震源的全波形反演数值计算,由于采用的方法可以给定计算节点上的多线程资源,易于编程,无需矩阵,有效的减少了外部krylov迭代的数量,并将提出的方法与常规全波形反演方法进行对比分析,证明了基于随机震源全波形反演更加高效. 相似文献
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Nonlinear fractional differential-algebraic equations often arise in simulating integrated circuits with superconductors. How to obtain the nonnegative solutions of the equations is an important scientific problem. As far as we known, the nonnegativity of solutions of the nonlinear fractional differential-algebraic equations is still not studied. In this article, we investigate the nonnegativity of solutions of the equations. Firstly, we discuss the existence of nonnegative solutions of the equations, and then we show that the nonnegative solution can be approached by a monotone waveform relaxation sequence provided the initial iteration is chosen properly. The choice of initial iteration is critical and we give a method of finding it. Finally, we present an example to illustrate the efficiency of our method. 相似文献
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指针式晶体管毫伏表可用于测量直流分量为零的非正弦周期信号电压的有效值.提出了改进其功能的设想. 相似文献
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Erkki Vilkman Eija-Riitta Lauri Paavo Alku Eeva Sala Marketta Sihvo 《Journal of voice》1999,13(2):303-312
The effects of prolonged (5x45 minute) reading (vocal loading) on fundamental frequency (F0), sound pressure level (SPL), subglottal (intraroral) pressure (p), and two glottal flow waveform parameters (AC amplitude of glottal flow, f, and negative peak amplitude of differentiated flow (d) of normal female and male subjects (N = 80) were studied. Two rest (morning and noon) and three loading (two in the morning and one in the afternoon) samples were recorded and analyzed. The glottal waveforms were obtained by inverse filtering of the acoustic pressure waveforms of speaking voice samples. The analyses were based on measurement and inverse filtering of the first stressed syllable of "paappa" words repeated 3x5 times for normal, as soft as possible, and as loud as possible phonation. In normal phonation the parameter values changed statistically significantly due to loading. In many cases the values obtained in the morning samples changed after the first loading session. This is interpreted as a vocal "warming-up effect." Especially in soft phonation p, d, and f were sensitive indicators of vocal loading. In both normal and soft phonation, the SPL, p, d, and f values tended to rise due to prolonged reading in the morning and afternoon samples, indicating increased effort (normal phonation) and a rise in the phonatory threshold (soft phonation). The lunch break vocal rest ("rest effect") considerably affected the parameter values in many cases. 相似文献
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气体放电中纳秒脉冲波形的实验研究 总被引:1,自引:0,他引:1
在利用示波器测试交流电弧发生器的一级放电回路的振荡波形时,在主振荡波形中观测到纳秒脉冲振荡波形.针对纳秒脉冲振荡波形进行了实验研究和初步的理论分析,所采用的实验方法能够为气体放电的纳秒脉冲研究提供一种新的实验依据. 相似文献