电子缩略新语卡(8)

Ｂ－ＩＳＤＮ　Ｂｒｏａｄｂａｎｄ　ＩＳＤＮ　宽带综合业务数字网Ｂ－ＭＡＣ　Ｂｒｏａｄｃａｓｔｉｎｇ　Ｍｕｌｔｉｐｌｅｘｅｄ　ａｎａｌｏｇ　Ｃｏｍｐｏｎｅｎｔ　（卫星图像传输方法）广播复用模拟部件Ｂ－ＳＲＡＭ　Ｂｕｒｓｔ　ＳＲＡＭ　突发方式同步型高速ＳＲＡＭＢＡＣＰ　ＢＡｎｄ　Ａｌｌｏｃａｔｉｏｎ　Ｃｏｎｔｒｏｌ　Ｐｒｏｔｏｃｏｌ（传输速度自动调节）频带配置控制协议ＢＡＴ　Ｂｅｓｔ　Ａｖａｉｌａｂｅ　Ｔｅｃｈｎｏｌｏｇｙ最佳可利用技术ＢＢ　Ｂａｓｅ　Ｂａｎｄ基带ＢＢ　Ｂｏｏｋ　ｔｏ　Ｂｉｌｌ　ｒ…     

共束声光可调滤光器研究

声光可调滤光器（ＡＯＴＦ）具有独特的光波长调谐功能，可望用于光通信的波分复用（ＷＤＭ）技术。而共束声光滤光器（ＣＢ－ＡＯＴＦ）兼顾了共线和非共线ＡＯＴＦ的优点。给出ＣＢ－ＡＯＴＦ的工作原理和设计方法。获得了在２０ｍＷ下９８％的衍射效率，旁瓣抑制优于３３ｄＢ和线宽０．８ｎｍ的结果。     

OPTICAL FIBER-MOBILE COMMUNICATION

ＯＰＴＩＣＡＬＦＩＢＥＲ－ＭＯＢＩＬＥＣＯＭＭＵＮＩＣＡＴＩＯＮ￥ＦＥＮＧＸｉ－Ｙｕ；ＳＵＮＴｉｅ－Ｃｈｅｎｇ（ＤａｌｉａｎＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈｎｏｌｏｇｙＤａｌｉａｎ１１６０２３）Ａｂｓｔｒａｃｔ：Ｔｈｅｔｅｃｈｎｉｑｕｅｏｆｍｏｂｉｌ...     

五品牌手机生产日期轻松辨

爱立信（ＥＲＩＣＳＳＯＮ） 输入（右*左*左*左*）后会显示： ＡＢＣＤＥＦ ＧＨＩＪ ＰＲＧＸＸＸＸＸＸＸＸＸ ＡＢＣＤＥＦ为年、月、日（ＹＹ／ＭＭ／ＤＤ） 诺基亚（ＮＯＫＩＡ） 输入*＃０００＃显示： ＶＸＸ·ＸＸ为软件版本, ＤＤ－ＭＭ－ＹＹ为生产日期（日－月－年）, ＮＸＸ－Ｘ为手机型号：如３３１０为ＮＨＭ－５。 摩托罗拉（ ＭＯＴＯＲＯＬＡ） 查ＭＳＮ（在手机标贴上）内容,ＭＳＮ长度为十位： ＡＡＡ－Ｂ－ＣＣ－ＤＤＤＤ ＡＡＡ为型号代码（Ａ７４－ Ｃｄ９２０／９２８, Ａ８４ ２０００）; Ｂ为产地代码（２－…     

OFDM仿真软件系统研究

本文将介绍一套自行开发的适用于多种传输系统（包括ＯＦＤＭ－ＤＡＢ、ＯＦＤＭ－ＨＤＴＶ和ＯＦＤＭ－ＤＶＢ等）的ＯＦＤＭ软件仿真系统，并分析载波频偏对ＯＦＤＭ－ＤＡＢ系统和ＯＦＤＭ－ＤＶＢ－Ｔ系统的影响，以及抽样时钟误差对ＯＦＤＭ－ＤＡＢ系统的影响，最后给出相应的仿真测试结果。     

高副载波复用光纤CATV系统的优化设计

高副载波复用（ＳＭＣＭ）ＡＭ－ＶＳＢ ＣＡＴＶ系统在国内正日渐引起人们的关注。本文提出了采用掺饵光纤放大器（ＥＤＦＡ）和线性化外调制器在系统中进行优化,以实现高副载波复用。并首次采用定量的无约束数值优化法,即单纯形法,对全系统中一些关键参数进行优化,从而为ＭＳＣＭ ＡＭ－ＶＳＢ ＣＡＴＶ系统的优化提供了一种有实际意义的通用方法。     

基于CDMA的HFC-CATV网络双向传输

当前,光纤同轴线混合（ＨＦＣ）有线电视（ＣＡＴＶ）网络主要用于电视广播,存在大量的空闲频带资源。本文提出一种基于码分多址（ＣＤＭＡ）的使ＨＦＣ－ＣＡＴＶ网络具有双向传输能力的方案,实现ＣＤＭＡ方式的该系统能进行宽带高速传输,与ＴＤＭＡ（时分多址）比较,ＣＤＭＡ方案可以抗窄带噪声干扰。     

C波段16W内匹配GaAs功率MESFET

Ｃ波段１６Ｗ内匹配ＧａＡｓ功率ＭＥＳＦＥＴ傅炜（南京电子器件研究所，２１００１６）１９９３年１２月２日收到ＡＣ－Ｂａｎｄ１６ＷＩｎｔｅｒｎａｌｌｙＭａｔｃｈｅｄＰｏｗｅｒＧａＡｓＭＥＳＦＥＴ￥ＦｕＷｅｉ（ＮａｎｊｉｎｇＥｌｅｃｔｒｏｎｉｃＤｅｖｉｃｅ...     

新闻举要

Ｐｈｉｌｉｐｓ半导体日前与ＴＣＰＣｏｎｎｅｃｔ　ＡＧ公司共同宣布：在世界上首次于一台机顶盒骨实现Ｓｕｎ公司的ＪａｖａＭｅｄｉａ　Ｆａｍｅｗｏｒｋ和Ｊａｖａ智能卡功能。此种先进数字机顶盒命名为ＴＣＰＣｏｎｎｅｃｔＭ@ｇｉｃ　Ｂｏｘ,其核心器件Ｐｈｉｌｉｐｓ半导体的ＴｅｉＭｅｄｉａ“超长指令字（ＶＬＩＷ）”处理器。Ｍｏｔｏｒｏｌａ半导体不久前宣布与ｎＣＵＢＥ合作,以最低价位推出强劲的可伸缩的流动交互式视频解决方案。作为视频服务器技术和解决方案领域的先进开发商,ｎＣＵＢＥ将以其ＭｅｄｉａＣＵＢＥ　４与…     

新品信息

新款３ＣｏｍＨｏｍｅＣｏｎｎｅｃｔＡＤＳＬ调制解调器可为两台ＰＣ同时共享ＡＤＳＬ访问提供简单的解决方案。３ＣｏｍＨｏｍｃＣｏｎｎｃｃｔ＆ｔｒａｄｃＡＤＳＬ调制解调器双链路提供一个ＵＳＢ（通用串行总线）端口和一个以太同端口,为ＰＣ需求发生变化的家庭提供理想的解决方案。ＩＲ创新双ＦＥＴＫＹ器件该器件,把高侧控制场效应管（ＦＥＴ）及低侧同步场效应管与并联的肖特基二极管（ＳｃｈｏｔｔｋｙＤｉｏｄｅ）集成,从而将直流一直流交流器的面积缩小了６０％。采用ＩＲＦ７９０１Ｄ１的交流器可提供高效的空载时间传导路径,在５．０Ｖ、３．３Ｖ和１．８Ｖ环境下,可为５Ａ峰值输出电流提供高达９６％的运行效率。安奈特新款多通道介质转换器这种转换器包括６端口和１２端口两种。每对端口都可以作为一个独立的通道使用。该介质能非常轻松地保证线路的连接质量,使目前为用户普遍使用的基于钢缆为介质的中型或大型以太网和快速以太网网络简单经济地升级到以光纤为主要介质的网络上。ＡＴ一ＭＣＦ１０和ＡＴ—ＭＣＦ１００系列多通道介质转换器可提供不同的端口密度和介质接口类型．并支持多模和单模光纤。ＮＢａｓｅ－Ｘｙｐｌｅｘ推出高速ＷＤＭ光纤通道新产品新产品ＷＤＭ４—ＦＣ有...     

Twofold Mur's first-order ABC in the FDTD method

In this paper, it is shown that the reflection error of Mur's first-order absorbing boundary condition (ABC) can be canceled effectively by applying the ABC twice to an electromagnetic (EM) field on two diagonally neighboring nodes on the x-t, y-t and t-t planes. Following this idea, we have developed a twofold Mur's first-order ABC (TMFABC), which is efficient to absorb both propagative and evanescent EM waves and very convenient for implementation to multilayered structures. TMFABC improves Mur's first-order ABC more effectively at lower frequencies. This is very important because most energy of a high-speed pulse is concentrated at lower frequencies     

A new absorbing boundary condition structure for waveguide analysis

The existence of evanescent waves and waves near cutoff frequencies limits the accuracy of the fields computed in waveguides using the finite-difference time-domain method, and prompted several researchers to design complicated boundary conditions, including combinations of perfectly matched layers and Higdon's higher order absorbing boundary conditions (ABCs). Instead, we employ a terminating structure in which the lateral walls are made absorbing in addition to the longitudinal walls. The undesirable lateral waves at the normal boundary interface are slowed down and effectively attenuated in the lateral walls, while the propagating waves are absorbed in the longitudinal walls. Numerical calculations for pulse excitation of a rectangular waveguide, using the simple Mur's first-order ABC, demonstrate the usefulness of the method     

Mur吸收边界条件的校正

本文分析了Mur吸收边界条件产生误差的原因,讨论了用散射中心法校正Mur吸收边界条件的问题,以二维情况下线源的辐射及方柱形导体的散射问题为例进行编程计算,且与未校正的同阶和高阶近似的Mur吸收边界条件作了比较,证明该方法是有效的,最后提出用坡印亭矢量的方向来校正Mur吸收边界条件的思想.     

FDTD analysis of a metal-strip-loaded dielectric leaky-wave antenna

The finite-difference time-domain (FDTD) method is used to analyze a dielectric leaky-wave antenna comprising metal strips etched on a rectangular dielectric rod. The radiation patterns of the leaky-wave antenna with and without the transition are determined by using FDTD. The effects of the launching discontinuity on the performance of the antenna are discussed. In addition, the application of the perfectly matched layer (PML) technique to the three-dimensional (3-D) dielectric waveguide and its performance, compared to those of the Mur's (1981) first-order and super-absorbing Mur's first-order absorbing boundary conditions (ABCs) are described. In addition, the effects caused by perturbation on the wave propagation characteristics of dielectric waveguide are also discussed. The FDTD results are verified by a W-band experiment and found to be in good agreement     

一种新的吸收边界条件及三维微波结构的FDTD分析

本文基于Ｚ－变换域上导出的一种新的有效的吸收边界条件和ＦＤＴＤ法对三维微波无源集成结构进行了分析。与Ｍｕｒ吸收边界条件、色散吸收边界条件等相比,这种新的吸收边界条件更精确有效。相应的软件可应用于复杂三维微波集成结构等效网络参数的精确快速提取。     

Techniques for implementation of the FDTD method on a CM-5 parallelcomputer

In this paper, techniques for efficiently parallelizing the FDTD method for radiation problems are presented. Methods of parallelizing the core FDTD algorithm, PML ABC, Mur's ABCs, and the near-zone-to-far-zone transformation are discussed. A technique which makes the parallel FDTD more efficient can be applied to Berenger's PML in a straightforward manner, and apparently makes the code for PML ABC faster. Performance of the code is shown, and the computer-time usage for various parts of the code is given. On a 32 processor CM-5, the core FDTD algorithm is 100 times faster than an existing serial code, run on a SUN SPARC-2 workstation, and the calculation of the radiation patterns for two orthogonal planes is approximately 27 times faster. The techniques can easily be extended to other cases, not included in this paper, such as FDTD codes for magnetic materials, and non-uniform-mesh FDTD codes     

采用PML的FDTD方法对矩形微带天线的研究

将完全匹配层(PML)吸收边界应用于微带结构中，对矩形微带天线进行了分析计算，给出了其时域和频域的仿真结果。结果表明，与传统的Mur边界相比，采用PML吸收边界具有反射小、馈源模型简单、收敛速度快等优点。     

Mur Absorbing Boundary Condition for Efficient Fundamental 3-D LOD-FDTD

This letter presents the implementations of Mur first-order absorbing boundary condition (ABC) for efficient fundamental scheme of 3-D locally one-dimensional finite-difference time-domain (LOD-FDTD) method. The Mur ABC is incorporated into the efficient fundamental scheme using consistent implementation and a novel implementation with lower reflection coefficient. Both implementations in the efficient fundamental scheme are compared and validated with the conventional LOD-FDTD scheme. By comparing the CPU time of both conventional and efficient fundamental schemes, it is ascertained that substantial gain in the overall efficiency may be achieved for the latter even with Mur ABC incorporated.      

Stability characteristics of absorbing boundary conditions inmicrowave circuit simulations

In this paper, we examine the stability properties of several absorbing boundary conditions in the finite-difference time-domain (FDTD) simulations of microwave circuits. The numerical experiments show that the stability characteristics of absorbing boundary conditions, e.g., Mur's (1981) and perfectly matched layers (PML), can depend upon the discretization of the computational domain     

Second-order absorbing boundary conditions for marching-on-in-order scheme

In this letter, we derive second-order absorbing boundary conditions (ABCs) for a marching-on-in-order scheme, which is a time-domain method with weighted Laugerre polynomials and free of stability constraint. This method does not have to deal with time steps, and may be computationally much more efficient than conventional finite-difference time-domain (FDTD)methods with too many time steps to complete a solution. Starting from the three-dimensional (3-D) case of the marching-on-in-order scheme, we deduce a second-order ABC and apply it to a 3-D microstrip line example. The results show the second-order ABC performs better than the first-order one for guided wave problems.