屏蔽视频电缆的辫接效应分析

辫接导线引起的电磁泄漏,是屏蔽视频电缆泄漏最严重的部分。利用广义二端口网络法和天线理论求解视频电缆的辐射;从理论上分析了产生这种结果的原因,并提出减少这种辐射的方法,该方法对辫接效应的抑制大于20dB。     

屏蔽视频电缆的辫接效应分析

辫接导线引起的电磁泄漏，是屏蔽视频电缆泄漏最严重的部分。利用广义二端口网络法和天线理论求解视频电缆的辐射；从理论上分析了产生这种结果的原因，并提出减少这种辐射的方法，该方法对辫接效应的抑制大于20dB．     

计算机视频屏蔽电缆的电磁泄漏＊

本文对视频(屏蔽)电缆的辫接效应(Pigtail Effect)及其辐射机制,进行了理论和实验研究;利用天线和传输线理论提出了屏蔽电缆共模辐射的物理模型和数学公式;分析和验证了辫接效应是导致屏蔽电缆产生辐射的主要诱因;提出了防护和抑制这种共模辐射的原理和手段。     

怎样提高放像质量

录像机的功能很多,但大多数用户最经常使用的功能就是放像。若能正确地使用录(放)像机,将能获得最佳的图像效果。1.跟电视机的配接要正确录(放)像机跟彩色电视机的配接主要采用射频电缆和视频/音频电缆两种方法。采用射频电缆配接时,录(放)像机将重放的视频/音频信     

利用RPR和MPLDS创建有效网络和新服务

通常的电缆网络设计用于从前端流向住宅用户的单向视频业务。随着宽带接入互联网的来临,这种情况就出现了变化。电缆网络经过几年的发展,从简单的用于模拟视频到已能提供数字视频和数据。电缆供应商通过原有同轴电缆设施的升级以便控制双向业务,这样,在宽带接入向居民用户渗入的市场中已掌握了主导权。虽然同轴电缆已成为“最后一公里”接     

久经考验的3M Scotchlok接线子

50年前,3M公司发明了第一个Scotchlok接线子.发明接线子是为了满足电信公司简化铜芯电缆接续的要求,并提高接续质量.当时,电话公司采用的是塑料绝缘电缆,这种电缆的质量稳定,但是接续非常困难.传统接续先要用刀去除塑料绝缘层,扭接电缆芯线并焊接,最后还要套上一个内含树脂的保护套.电话公司希望能有一种快速、有效的接续方法,以便使电话服务能够快速应用于家庭与商业用户.Scotchlok接线子大大简化了电缆接续过程,只要把电缆插入Scotchlok接线子,压接一下就完成了.     

在现行视频传送中用嵌入内容法来增加容量

1 引言 在今日之急速变化和竞争的环境中,电缆经营者经常地寻找新的业务以取得更多收入。他们经营面对的挑战是,应尽量利用好现有的宽带接人基础设施。在这种环境中,可以最小的投资在目前的视频传输中     

多芯屏蔽视频电缆转移阻抗的测试研究

本文讨论了基于"三同轴法"的多芯屏蔽视频电缆转移阻抗的测试原理和方法,据此方法我们设计给出了使用矢量网络分析仪作为信号源及接收器实现多芯屏蔽视频电缆转移阻抗测试的测量装置和测试结果,最后基于测试结果我们对多芯屏蔽视频电缆的屏蔽效能进行了验证,从而证明了多芯屏蔽视频电缆转移阻抗对信息安全的重要意义.     

高频辐射电缆

Kabelmetal公司展出了一种新型高频辐射电缆,其外导体由凹凸格子状皱纹铜带制成,它包围在内导体的聚乙烯绝缘上大约覆盖1/2左右,从而可以得到高的耦合阻抗,把电缆内部传输的高频功率的一部分辐射到周围的空间。同样,这种高频电缆可以沿着纵方向接收并传输高频能量。这种高频电缆可以在移动的发射机与接收机之间提供通讯。由于电缆的有效辐射的范围有限制,其可以应用的工作频率范围同样也有限制,这是已经反复证明了的。     

多T接电缆混合线路故障测寻分析与探讨

随着城市电网地不断改造和电力电缆的广泛运用,高压电力电缆对城市电网的发展起着主导作用.电缆线路的增多和改造,也使T接电缆线路也不断出现,甚至出现一条电缆线路有多个T接电缆头.电缆一旦发生故障,寻找起故障点来十分困难,由于电缆应用规模的扩大、运行年限的增长,电缆故障也会越来越频繁,这就使得每年供电企业都要花费大量的人力物力,而且还将给企业带来难以估计的停电损失.因此,如何快速、准确、经济地找出电缆故障点,一直是供电企业跟施工单位探讨的首要问题.本文结合实际运行的多T接电缆线路故障实例,对测寻方法进行深入分析研究.     

A quasi-static technique for evaluation of pigtail connections

It is shown that the analysis of `pigtail' connections between a transmission line and a ground plane can be simplified by dividing the problem into two parts: the radiating transmission line and the pigtail loop. The problem need be solved only once by the moment method code for several different pigtail geometries. The effect of the pigtail can be taken into account quite accurately through the use of a quasi-static evaluation of pigtail loop inductance. The approximation is valid as long as the pigtail loop (with image) is less than a quarter wavelength in circumference     

Effect of Pigtails on Crosstalk to Braided-Shield Cables

An investigation of the effect of pigtail sections (terminal segments of braided-shield cables in which the shield braid has been stripped back exposing the interior wire) on the electromagnetic coupling to braided-shield cables from adjacent wires is presented. Experimental and computed data indicate that, even though the lengths of these pigtail sections may be only a very small portion of the total cable length, they may, over certain frequency ranges, constitute the dominant coupling mechanism for the braided-shield cable. For situations in which pigtail coupling is dominant, the shield simply serves to reduce the exposed section of the interior wire from what it would be if no shield were present. Thus the shield provides some reduction in coupling, but the effectiveness of the shield in reducing crosstalk is shown to be as much as 30 dB (over certain frequency ranges) less than it would be if the pigtail sections were eliminated. A low-frequency model which explains this phenomenon is given. The effect of various shield grounding configurations is also investigated.     

软辫线长度对主动和被动屏蔽效能的影响

针对软辫线长度所带来的电磁兼容问题,给出被动屏蔽效能和主动屏蔽效能的定义,并利用被动屏蔽效能和主动屏蔽效能对软辫线效应进行了评价。仿真实验及理论计算结果表明：随着软辫线长度的变化,被动屏蔽效能和主动屏蔽效能变化的趋势相同,但数值差别很大,不能等效使用。     

Shielding effectiveness of `pigtail' connections

The shielding effectiveness of a `pigtail' connection between a coaxial transmission line and a ground plane is treated rigorously by the method of moments, as a function of the type and number of pigtails and frequency. Numerical results show that the type of pigtail connection is crucial with regard to radiation and shielding effectiveness, even though the pigtail itself does not radiate significantly. All pigtails are not equal, even though they can be short electrically. A short pigtail is significantly better than a longer one. A long pigtail connection can actually enhance radiation. Finally, multiple pigtails yield significant improvement over the single pigtail only for short pigtails. Numerical and experimental results are compared and found to be in good agreement     

高双折射保偏光纤拍长测试及Mueller矩阵分析

为了测量高双折射保偏光纤的拍长,采用偏光干涉效应的方法,构建由宽谱光源、带保偏尾纤的起偏器和光谱分析仪组成的全光纤光路测试系统。从理论上用Mueller传输矩阵方法推导了到达光谱仪的光强公式,利用该方法构建实验系统对熊猫型保偏光纤的拍长进行了测试,获得了该保偏光纤拍长的测量数据。结果表明,由待测保偏光纤的偏光干涉效应引起的光强波动以一定的周期间隔表现在光谱变化上,波动的相对幅度与待测保偏光纤主轴与起偏器的保偏尾纤主轴夹角有关,当夹角均为±45°时波动的相对幅度最大。只要在实验中测量出光谱波动的周期,就能够根据理论计算出给定波长处的保偏光纤的拍长。     

Transmission-Line MNodeling of Shielded Wires for Crosstalk Prediction

The adaptation of a transmission-line model to the prediction of crosstalk in shielded-wire circuits is presented. The incorporation of pigtail sections of the shielded cable into the transmission-line model is discussed, and the presence of the pigtail wires is shown to be important. Experimental results are presented which illustrate the prediction accuracy of the model.     

光网络哑资源深度学习智能管理系统

现阶段光网络哑资源的管理多采用人工方式进行监控管理,而引入电子标签的智能光分配网络（Optical Distribution Network,ODN)因成本高、改造实施困难导致运营商无法有效提高ODN网络质量。通过引入二维码标签及标签分别对分光器及尾纤进行标识,利用深度学习技术,采用Faster-RCNN网络对哑资源中尾纤、尾纤标签、分光器、二维码等信息进行统一识别管理,mAP(Mean Average Precision)达82.96%,满足实际需求,实现了哑资源智能管理,降低了管理与维护成本。     

Radiation properties of a pigtail-terminated coaxial transmissionline

The method of moments is used to study the shielding effectiveness of a pigtail-terminated shielded wire (coaxial line) above a perfectly conducting ground plane. Numerical computations are performed in the RF frequency range, i.e. 25-1000 MHz. Pigtail wires on either or both ends of the shield are considered. Results are compared to those from the ungrounded case (floating shield). Results show that the presence of pigtail wires as ground connections at RF frequencies is undesirable and may further enhance radiation. The impedance terminations have a small effect on the shielding effectiveness of the antenna structure