System Considerations for Short-Haul Multichannel Subscriber Carrier

Solid-state technology is available to permit the design of multichannel station carrier systems with "prove-in" distances of 18 kft or less. Customer acceptance of these systems will depend on transmission performance, installation and maintenance ease, service reliability, and application restriction, as well as the per-channel installed cost. This paper discusses these parameters with regard to digital and analog carrier and carrier-concentrator systems.     

Subscriber Line Equipment for an Elastic Carrier Switching System

This is the third of three papers [l], [2] dealing with an elastic carrier-concentrator system. The functioning of the subscriber line equipment is described herein. The system serves 256 telephone subscriber lines by digital concentration switching and transmission of multiplexed message channels over a singleT1transmission line. The concentration switching function is nonblocking. Message channels are the individual communication links between terminals and are created on demand at the request of active subscriber lines. They are not merely inactive without service requests; they do not exist unless service is requested. The created message channels serve for their normal communication function and, in addition, carry for each line the ancillary functions of dialing, ringing, and pay-station coin disposal. Message channels are coded by delta modulation, which permits flexible digital concentration and provides a smooth tradeoff of channel quality versus the instantaneous traffic load. Each of two complementary subscriber line interface units, one per line at each end, provides the delta-modulation encoding and decoding functions for the analog voice-band signal input and output and, by overriding the delta codec, provides the desired signaling functions of dialing, ringing, etc. The line interface units provide the major equipment interface between the subscriber line and the digitalT1line. An integral test facility permits remote loop-back of any selected subscriber line unit via a test channel to the office terminals and at the same time connects the subscriber loop to an auxiliary programmed test facility which may transmit pertinent loop-test results to the office terminal.     

Rural Subscriber Loops via Carrier and Radio

Ever since carrier was developed for trunk usage, carrier for subscriber use, either over wire or radio, has been considered as a means for providing telephone service in rural areas. Starting with the Bell System development of its"M"type power line carrier, there have been 34 years of progress and subscriber carrier is now a reality. It is now beginning to become widely accepted in the telephone industry. Every year improvements in the state of the art are made. There is little doubt today that more and more subscriber carrier on wire lines and radio will be used in future years. This concise paper includes the history of the development of subscriber carrier and radio in the Telephone Program of the Rural Electrification Administration (REA). Also, the authors attempt a prognosis of what will happen in the next ten years (or longer). Suggestions are made for improvements still deemed necessary in equipment of this type.     

ENUM系统架构及寻址解析的探讨

时至今日，网络融合的呼声越来越高，软交换的出现使之成为可能．由于将来的终端都构架在软交换的核心网络之上．终端之间的寻址变得很久成为一个很现实问题，所以在ITU—T、IETF的合作下制定了RFC2916的标准，旨在推动电路网与分组网的结合，两者相辅而成。本文分析了ENUM架构和寻址解析方法，进而给出基于传统和基于软交换的ENUM的实现方法．希望对ENUM技术的应用能起到推动作用。     

Expected Crosstalk Performance of Analog Multichannel Subscriber Carrier Systems

This paper determines the intelligible crosstalk performance of analog multichannel subscriber carrier systems. Using a 0.1 percent probability of intelligible crosstalk objective, the calculations determine that the equal level far-end crosstalk loss must exceed 55.6 dB. Based on crosstalk measurements of in-service cables in South Central Bell, it is shown that only a small fraction of the pairs fail the crosstalk objective. Hence, it is concluded that multichannel analog subscriber carrier systems can be applied without any cable crosstalk constraints.     

浅谈用户管理系统

有线电视行业多年来一直采用包月制的粗放型经营体制,数字电视可以实现端到端的控制,通过建立和使用用户管理系统(SMS,Subscriber Management System)将使有线电视管理由粗放型管理走向集约化管理,大大提高广播电视的管理水平和服务水平。     

基于数字电视网的用户管理系统的研究

在数字电视系统框架的基础上,引入了流媒体技术,提出了可扩展的用户管理系统的探索,以满足数字电视业务不断更新的需求。     

多载波系统中帧同步和载波同步的最大似然估计算法

本文提出一种用于多载波系统的帧同步和载波同步的最大似然估计算法.它利用多载波系统循环冗余扩展的保护间隔携带的信息进行同步估计,避免了基于导频符号的同步估计带来的频率和功率资源的浪费.计算机仿真显示,本算法在加性白高斯噪声信道能达到最佳性能,在慢衰落信道下也具有较好的性能.     

一款车载GPS系统解决方案

提出一款车载GPS系统的解决方案     

基于Internet的CATV用户服务系统

结合有线电视台面向用户服务的需要,使用Java语言开发了一套基于Iternet的用户服务系统,实现用户网上查询,报装和报修等功能,该系统采用B／S（Browser/Server)系统模式,并运用Java Servlet ,JDBC(Java Database Connection),SQL等技术,使用了Apache服务器软件进行系统的开发。     

An ISDN Subscriber Loop Transmission System Based on Echo Cancellation Technique

This paper proposes an ISDN subscriber loop transmission system based on an echo cancellation technique which fully supports the CCITT recommended basic interface for ISDN, i.e.,B + B + Dover metallic cables. System design considerations of cable loss, crosstalk, impulsive noise, and system requirements such as power feeding on a caLl-by-call basis are discussed, and a transmission system is proposed. The proposed system is characterized by the use of a new line code, named "modified biphase code." The use of this code with fixed line loss equalization and coherent detection achieves circuit simplification. A special adaptation algorithm is incorporated with the echo canceller that significantly reduces convergence time. Experimental results show satisfactory performance with respect to the residual echo and the bit error rate. Since the system requires only a simple nonadaptive circuit for analog portion, it is suitable for LSI implementation.     

A Digital Subscriber Set

The Electronics Research Laboratory at the Norwegian Institute of Technology has since 1974 studied PCM-transmission in the local subscriber plant. A short discussion of this work is presented together with choice of design parameters and concept for a digital subscriber set. Construction and laboratory testing of the digital subscriber set are described. The paper concludes with a discussion on future development.     

一种基于MJPEG2000的实时跳帧图像传输系统

介绍一种基于MJPEG2000格式的无线实时图像传输系统中跳帧视频传输的设计与实现,图像的压缩与解压缩利用专用硬件ADV202实现,通过FPGA实现跳帧与补帧,在信道速率受限的情况下,能有效提高传输图像质量.     

基于ESB技术的系统集成框架的研究

鉴于大多数高校存在诸多遗留系统,而这些信息系统之间缺乏关联,致使办公不能协同,而传统的集成方式存在耦合度高,不易扩展等问题,文中讨论了ESB技术的优势,结合本校的具体情况,介绍了一种利用ESB技术进行异构系统集成的框架,该框架通过引入SCA来绑定各种传输协议,从而实现服务间的松散耦合。最后,原型系统的实例证明了该集成方案确实可以使高校从遗留系统中获取更多的价值。     

基于 B／S 的用户管理系统的研究与设计

介绍了基于B/S架构的用户管理系统,设计分为两个分系统,以前后台的方式运行。前台是一个综合业务系统,完成面向各类用户的各项运营功能及数据统计。后台负责处理订单,形成相应的授权信息,并将授权信息传送给CA系统。主要对前台系统的功能及数据表设计进行详细的说明,并介绍系统数据安全机制,最后将系统接入数字电视系统中联合测试,证明系统的可行性和有效性。     

数字电视用户管理系统探讨

在有线数字电视的运营系统中,用户管理系统(SMS)是整个系统的核心。SMS在逻辑上采用分层结构,如分为接入层、业务层、数据层等,在物理上采用了B/S与C/S两者相结合的方式,充分发挥了B/S与C/S体系结构的优势,弥补了二者的不足。     

数字电视用户管理系统

课题实现了数字电视用户管理系统的设计与开发,以Oracle数据库作为后台数据库,以C Builder 6作为前台开发工具,包括表的设计与界面的设计.实现了数字电视用户管理系统基本功能,基本上满足了实际商业运营的需要.     

基于扩频载波技术的集中抄表系统

本文在分析了集中抄表系统通信信道的基础上,提出采用扩频载波技术的电力载波通信方式,研制成功了基于扩频载波通信技术的集中抄表系统,研制结果表明系统实时通信成功率高,数据传送可靠,能满足用户的需要。     

基于电力线载波的信息发布系统

电力线载波通信提供了实用的新兴通信手段,具有良好的前景和市场潜力。本信息发布系统基于BWP10A电力载波模块,采用电力线,主机通过串口发布指令或信息,从机在通讯距离内,只要插上220V交流电源即可将信息处理之后通过LED点阵显示出来,无需铺设其它数据线,极大地方便了信息的发布。