四川广电网络攀枝花分公司光纤入户初探

光纤入户是当代通信传输的重要发展目标,而广电网络由于历史原因一直是以同轴电缆进行电视信号的传输,随着时代的不断进步,广电网络也不断地完善着自身的网络品质,大多数地区的广电网络已经完成了光纤到楼栋的网络改造,但是由于改造成本及传输技术等各种因素,光纤入户对大多数广电网络来说还是一种应积极探索的新技术。结合攀枝花广电网络传输模式,对光纤入户技术进行探讨。     

HFC网络中CMTS控制系统的研究

CMTS控制系统是HFC网络中关键设备之一,简介了BCM1250的特性并且比较了几种典型的架构,在此基础之上引出了CMTS的控制系统结构,之后详细描述了该系统中DOCSIS包的处理流程.     

Comparison of the refrigerants HFC 134a and CFC 12

A comparison of the refrigerants HFC 134a and CFC 12 has been carried out and the results from a theoretical analysis and from tests with an open piston compressor are reported in this paper. The results indicate that the tested compressor will give a greater refrigerating capacity with HFC 134a than with CFC 12 for certain operating conditions. However, the results also indicate an increased operating power for the compressor over the entire temperature range. As a result the coefficient of performance is decreased. Another noticeable result is dependency of the compressor's isentropic efficiency on temperature when using HFC 134a. This might be explained by the properties of the polyalkene glycol oil which is used with HFC 134a. The increased cost of using HFC 134a is justified if the environmental aspects are considered and the practical problems, such as the influence on the material in the refrigeration cycle, can be solved.     

A Rational Helmholtz Fundamental Equation of State for Difluoromethane with an Intermolecular Potential Background

A new fundamental thermodynamic equation of state for difluoromethane was developed by considering the intermolecular potential behavior for improving the reliability in the gaseous phase. Reliable second and third virial coefficients are introduced in accordance with the principle of a unified relation of the intermolecular potential energy and the fundamental equation of state. The fundamental equation of state is able to provide reliable thermodynamic properties even at low temperatures or in the region near saturation where precise and accurate experimental data are not available. The estimated uncertainties of calculated properties from the equation of state are 0.07% in density for the liquid phase, 0.1% in pressure for the gaseous phase, 0.35% in pressure for the supercritical region, 0.07% in vapor pressure, 0.2% in saturated-liquid density, 0.7% in saturated-vapor density, 0.01% in speed of sound for the gaseous phase, 0.7% in speed of sound for the liquid phase, and 0.6% in isochoric specific heat for the liquid phase. The equation is valid for temperatures from the triple point to 450 K and pressures up to 72 MPa.     

接入网技术及其应用

介绍了各种类型的接入网技术及在国内外的应用情况,并对其发展前景进行了展望和预测。     

海拉尔铁路分局有线电视光缆网络设计

采用光纤传输技术对有线电视网络系统进行改造势在必行，从网络升级的主导思想、技术方案的选择、频率的配置、系统结构的确立、技术指标分配等方面，对海拉尔铁路分局有线电视860MHz光缆网络的方案进行了论证设计。     

HFC网中EDFA的应用研究

在HFC光网络段中 ,可利用EDFA来延长系统的传输距离。采用优化设计法对HFC网络进行工程设计 ,就其对HFC网络性能指标影响展开讨论。分析表明 :加入EDFA后 ,对CSO ,CTB基本没有影响 ,而对CNR影响较大 ,当光网络距离小于 2 94km时 ,可以不考虑色散的影响     

路由测距及光节点优化分组的VB编程实现

介绍了CATV光纤链路系统设计采用光节点优化分组的必要性，比较详细地阐述了进行人工分组中光功率，分光比等参数的计算方法，同时给出利用VisualBasic6．0编制应用程序的步骤、程序源码和程序使用中的注意事项。     

莆田市HFC网络的设计和实践

主要介绍了莆田市HFC网络的设计方案,包括指导思想、设计规划、网络拓扑结构、射频指标验证、光纤干线网设计、同轴电缆系统改造等.     

榆阳区五乡镇有线广播电视网络规划方案

本文介绍了整体解决省广电网络榆阳区支公司镇川等南部五乡镇有线广播电视网络技术方案。