对有线电视常用器件进行质量粗测的几点体会

论述基层台站用于检测分配器、分支器、电缆的损耗和放大器的增益及频响所用信号源的设置，以及检测时的注意事项。另外提出粗测经过检修后的放大器失真指标的简易办法。     

MULTISCALE OPTIMIZATION OF FLOW DISTRIBUTION BY CONSTRUCTAL APPROACH

Constructal approach is a recent concept allowing to generate and optimize multi-scale structures, in particular, branching structures, connecting a microscopic world to a macroscopic one, from an engineer＇s point of view. Branching morphologies are found in many types of natural phenomena, and may be associated to some kind of optimization, expressing the evolutionary adaptation of natural systems to their environment, In a sense, the constructal approach tries to imitate this morphogenesis while short-cutting the trial-and-error of nature. The basic ideas underlying the constructal concept and methodology are illustrated here by the examples of fluid distribution to a multi-channel reactor, and of the design of a porous material and system for gas adsorption and storage. In usual constructal theory, a tree branching is postulated for the channels or flow-paths or conductors, usually a dichotomic tree （every branch is divided into two ＂daughters＂）. The objective function of the optimization is built from the resistances to mass or heat transport, expressed here as ＂characteristic transport times＂, and the geometric result is expressed as a shape factor of a domain. The optimized shape expresses the compromise between the mass or heat transport characteristics at adjacent scales. Under suitable assumptions, simple analytical scaling laws are found, which relate the geometric and transport properties of different scales. Some challenging geometric problems may arise when applying the constructal approach to practical situations where strong geometric constraints exist. The search for analytical solutions imposes simplifying assumptions which may be at fault, calling for less constraining approaches, for example making only weak assumptions on the branching structure. Some of these challenges are brought forward along this text.     

分米波开关板设计

本文简要介绍分米波开关板的设计方法,并对各方案进行比较,分析如何在保证电气指标的基础上,降低制造成本,满足部颁标准《电视、调频天馈线系统部件输入端电器指标要求》。     

VSC7173：串行ATA分配器、缓冲器

VSC7173是Maxim推出的一款串行ATA分配器、缓冲器,可为1．5Gbps和3．0Gbps链路实现2：1容错切换。对于冗余、负载分配非常关键的高可靠性存储子系统,这项功能非常适合双主机（例如I／O控制器）必须连接单端口磁盘驱动器的应用。I／O控制器的输出复用到串行ATA驱动器,串行ATA驱动器的输出经过缓存,复制到I／O控制器。     

几种数字电视故障分析

1 反射对数字电视信号的影响 在模拟信号传输中,反射的影响仅仅是在图像上出现重影,而在数字电视系统中,影响则要严重得多。在日常的维护工作中,曾多次有用户反映数字电视信号出现马赛克及画面停顿现象,经维护人员排查发现,很多是由用户家中电缆的不同轴（例如使用不规范的对接头、用其他线充当同轴电缆、电缆弯曲半径不符合要求、压扁等）、分支分配器有空闲头未做终端匹配、电缆内部短路断路绝缘劣化、使用不合格器件所引起,     

基于砷化镓工艺的集成式功分器

A compact lumped integrated power divider with low insertion loss using 0.5 μm GaAs pHEMT technology is presented. The proposed power divider uses the π-type LC network for transmission line equivalence and a thin film resistor for isolation tuning simultaneously. The quality factor of the inductor is analyzed and synthesized for insertion-loss influence. The measured insertion loss is less than 0.5 dB when the operating frequency is within the range of 5.15-6.15 GHz. The return loss and isolation are better than 15 dB and 20 dB, respectively. The compact dimension of the power divider is as small as 0.9 × 0.85 mm^2. The measured results agree well with the simulated ones.     

县级电视台现场直播的实现

介绍小型电视台的现场直播技术,重点对仪征电视台电视直播系统的设计与配置,以及信号系统．通讯系统．电源系统等进行了详细的介绍,并分析了现场直播应注意的问题。     

半模基片集成波导(HMSIW)三分贝功率分配器

基片集成波导(SIW)具有损耗低、性能好、易于集成等优点,作为一种新型的导波技术已经被广泛地用于微波与毫米波电路.但是对于微波低频段,基片集成波导器件的尺寸偏大.最近,一种新的导波结构--半模基片集成波导(HMSIW)被提出.与基片集成波导相比,半模基片集成波导保留了基片集成波导的优点,同时在尺寸上缩小近一半,损耗也更低.本文提出了两种结合半模基片集成波导与基片集成波导技术的三分贝功率分配器,仿真结果与实验结果一致.