8.1 主要技术性能 输出脉冲：正/负极性的方波； 脉冲幅度：2kV（50Ω 匹配负载时测，下同），连续 可调； 脉冲上升时间：1ns±30%； 脉冲宽度：50ns～1000ns（每 50ns 为一增量，可调）； 操作方式：手动（按一次按钮，产生一个脉冲）、自 动（20Hz～80Hz，可调节）及电源同步（50/60Hz）； 相位：在电源同步的情况下，脉冲在电源波形上的相 位自 0°～360°连续可调。 可见，高频噪声模拟器毕竟与脉冲群发生器不同。首 先，波形不同（一个是方波，另一个是 5/50ns 三角波）。 其次，高频噪声模拟器的脉冲在时间上均匀分布；脉冲群 则是成群出现。要指出的是，高频噪声模拟器输出的 2kV 脉冲实际上和脉冲群发生器的 4kV 脉冲是相当的。前者 用 50Ω 匹配负载测得的（高频噪声模拟器的内阻抗也是 50Ω），故模拟器内部的电容电压实际上是 4kV。脉冲群 发生器的内阻是 50Ω，当电压为 4kV，用 50Ω 匹配负载 测得的脉冲也将是 2kV。 高频噪声的“高频”是指波形中含有谐波成分的频率 极高。 4.2 工作原理简述 下图为高频噪声模拟器脉冲发生线路的简图及输出波 形： 准备状态 Cs 充电己结束，作为延时线使用的电缆线 分布电容也充电到 HV。 水银开关闭合时，由于负载电阻与延时电缆的阻抗相 等，在电阻上得到的电压将是 +1/2HV。 水银开关闭合瞬间，由于回路阻抗发生突变，有一部分 能量（幅值也是 +1/2HV）经延时电缆向高压电源方向反射。 反射波到达 170kΩ 电阻处，由于电阻的阻值远大于 电缆线的阻抗，要形成第二次反射，属开路反射，反射波 要反相以 -1/2HV 向负载方向反射。 当第二次反射波到达负载时，正好和原来的 +1/2HV 相抵消，形成一个完整方波。方波宽度等于电磁波在延时 线上来回反射的时间。 上述分析预示，改变延线的长度，将改变高频噪声模 拟器的输出脉冲（方波）的宽度。 当负载阻抗与延时电缆不匹配时，波形会发生畸变。 ① 高频噪声模拟器外形及操作简述　　　　　　　　 ※输出脉冲的宽度通过改变 联接各分段延时线的组合关 系来实现 电源线抗扰度试验用仪器内部的耦合/去耦网络来做。 信号线抗扰度试验用电容耦合夹来做。 高频噪声模拟器的脉冲输出端子用电缆输出，电缆另 一端的芯线与外层屏蔽形成短路圈，可将电压脉冲转变成 电流脉冲，而将能量集中在圈的中央。当这个短路圈靠近 对辐射敏感的设备或线路时，可使敏感设备产生误动作。 因此，这个试验方案可用来做设备的局部辐射抗扰度试验 （定性试验）。

A. 导线电感 (1) 一定长度的导线电感 载流导线总是闭合的，包围的面积越大，磁链ψ越大，电感就越大。一段导线是总自感的一部 分。导线长度为l(cm),直径为d(cm),磁导率为μ=μ0，则低频电感 )75.0 4 (ln20 −= d l lL ×10-7(H) （3-25） 如果导线长度很短(l<100d)，在括号内增加一项d/2l。在很高频率(大于1GHz)时，导线电感趋于 极限值 )1 4 (ln2 −=∞ d l lL ×10-7(H) (3-25a) 高频时，由于导线的集肤效应减少了磁场空间，使得磁场减少，电感量减少。一般用式（3-25） 计算，中频时（数百kHz）最大有6％的误差，高频时只有2％误差。这在工程上完全允许的。 例4：求一段直径为1mm，长50cm的铜连接线的低频电感量。 解：根据公式(3-25)得到 77 0 1075.0001.0 5.0 ln5.0210)75.0 4 (ln2 −− ×⎟ ⎠ ⎞ ⎜ ⎝ ⎛ −×=×−= d l lL =0.546μH （2）单导线对大平面(地回路)之间电感(图3-13) 单导线直径为d(m)，长度为l（m）,导线与平面之间平行，导线与平面间距离为h(m),其电感量 ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ++ ++ = d h hll dll lL 4 ln 4 4/ ln2 22 22 ×10-7(H) + [ ]2 4 4 2 22 2 2 2l h l d h d+ − + + − +/ / ×10-7(H) (3-26) 如果d<>h时，以上公式可进一步简化为 ) 4 (ln2 d h lL = ×10-7(H) (3-26c) （3）两根平行导线电感（图3-14） d h 图 3-13 导线平行地线

Understanding Digital Signal Processing, Third Edition, is quite simply the best resource for engineers and other technical professionals who want to master and apply today’s latest DSP techniques. Richard G. Lyons has updated and expanded his best-selling second edition to reflect the newest technologies, building on the exceptionally readable coverage that made it the favorite of DSP professionals worldwide. He has also added hands-on problems to every chapter, giving students even more of the practical experience they need to succeed. Comprehensive in scope and clear in approach, this book achieves the perfect balance between theory and practice, keeps math at a tolerable level, and makes DSP exceptionally accessible to beginners without ever oversimplifying it. Readers can thoroughly grasp the basics and quickly move on to more sophisticated techniques. This edition adds extensive new coverage of FIR and IIR filter analysis techniques, digital differentiators, integrators, and matched filters. Lyons has significantly updated and expanded his discussions of multirate processing techniques, which are crucial to modern wireless and satellite communications. He also presents nearly twice as many DSP Tricks as in the second edition—including techniques even seasoned DSP professionals may have overlooked. Coverage includes New homework problems that deepen your understanding and help you apply what you’ve learned Practical, day-to-day DSP implementations and problem-solving throughout Useful new guidance on generalized digital networks, including discrete differentiators, integrators, and matched filters Clear descriptions of statistical measures of signals, variance reduction by averaging, and real-world signal-to-noise ratio (SNR) computation A significantly expanded chapter on sample rate conversion (multirate systems) and associated filtering techniques New guidance on implementing fast convolution, IIR filter scaling, and more Enhanced coverage of analyzing digital filter behavior and performance for diverse communications and biomedical applications Discrete sequences/systems, periodic sampling, DFT, FFT, finite/infinite impulse response filters, quadrature (I/Q) processing, discrete Hilbert transforms, binary number formats, and much more

datcom_java二次开发 USAF Digital datcom_java二次开发

single-sensor imaging methods and applications for digital cameras No.10cp

Digital-Image-Processing-Project 数字图像处理大作业，图像细粒度分类，CUB-200-2011，Peking University

A Guide to Digital Design and Synthesis, Second Edition

在线学习每年都在Swift增长。 但是，有一些因素与传统的课堂学习方法不同。 在在线学习中，教师（主持人）无法一次监视每个学生（参与者），这在课堂学习中是可能的。 因此，难以识别学习者的注意力。 本文提出了一种深度学习方法，用于在边缘计算中使用卷积神经网络检测学习者的注意力水平。 另外，跟踪浏览器的活动以进一步识别学习者的注意力水平。 神经网络将学生的注意力分类为四个不同类别之一，即高度专心，专心，不太专心和至少专心。 此关注级别是在边缘设备上计算的，并且仅最终输出发送到服务器。 结果，消耗了少量的带宽并且尊重了用户的隐私。 使用“电子环境中的情感状态数据集”（DAiSEE）对CNN模型进行了训练。 在实验过程中，有效的系统精度达到了84.1％。

The hand is quicker than the eye. In many cases, so is digital video. Maintaining image quality in bandwidth - and memory - restricted environments is quickly becoming a reality as thriving research delves ever deeper into perceptual coding techniques, which discard superfluous data that humans cannot process or detect. Surveying the topic from a Human Visual System (HVS)-based approach, "Digital Video Image Quality and Perceptual Coding" outlines the principles, metrics, and standards associated with p erceptual coding, as well as the latest techniques and applications. This book is divided broadly into three parts. First, it introduces the fundamental theory, concepts, principles, and techniques underlying the field, such as the basics of compression, HVS modeling, and coding artefacts associated with current well-known techniques. The next section focuses on picture quality assessment criteria; subjective and objective methods and metrics, including vision model based digital video impairment metrics; testing procedures; and international standards regarding image quality. Finally, practical applications come into focus, including digital image and video coder designs based on the HVS as well as post-filtering, restoration, error correction, and concealment techniques. The permeation of digital images and video throughout the world cannot be understated. Nor can the importance of preserving quality while using minimal storage space, and "Digital Video Image Quality and Perceptual Coding" provides the tools necessary to accomplish this goal.

本标准结合我国广东等地多年来开展的数字声音广播试验和大量测试研究报告，并结合我国实际情 况而制订。 为有利于中文数据信息功能的实现，本标准引用GB13000.1和GB2312标准中的相关内容，对接收机 的内置中文字库作了规定。