Implementation of intelsat IDR operation

Over the next few years INTELSAT IDR carriers are expected to replace analogue FDM/FM carriers carrying trunk public switched telephony traffic. This paper describes the activities necessary to implement INTELSAT IDR operation into an existing or new earth-station. The operational planning aspects discussed include the initial traffic and marketing forecasts to determine the IDR carrier requirements, use of DCME, the type of signalling system to be used and the interfaces with the terrestrial network, including synchronization. Typical earth-station equipment configurations for IDR operation are described, and the design options that should be considered for the DCME, IDR modem, frequency converters, HPA and control and monitor systems are discussed.     

The role of intermediate data rate (IDR) carriers in the intelsat system and their impact upon operational planning

IDR carriers will provide a significant proportion of the services in the INTELSAT system within the next few years. A number of factors have been identified which must be considered when developing satellite operational plans, in order to ensure satisfactory operation of an integrated environment consisting of a number of different access techniques and modulation methods.     

A comparison of the implementation and annual operating costs of IDR and TDMA in the intelsat system

The outcome of a preliminary systems cost study which compares the cost of operating INTELSAT intermediate data rate (IDR) and time division multiple access (TDMA) stations under various conditions is reported. The differences in the annual cost of operating the two candidate methods over the range of 1 to 1000 terrestrial channels are derived under the conditions of no CME, DSI only and the use of DCME. For DCME the effect of one, two, three and four destinations per DCME is considered. The results show that while the initial cost of the TDMA equipment is higher than with IDR, the annual cost of operating the systems is dominated by the space segment costs. For this reason the greater bandwidth efficiency, inherent multidestinational capability and ease of capacity expansion of the TDMA system give it a lower annual operating cost, even at fairly moderate earthstation capacities (e.g. for DCME with two destinations TDMA becomes cheaper than IDR for capacities in excess of about 300 channels). There are attributes of both systems which will also influence the network planners' decision. The IDR system is modular in that costs associated with implementation are incurred more gradually than with the TDMA system. Furthermore, IDR is to a great extent an extrapolation of the current FDM/FM/FDMA practice. However, since the equipment costs are small compared to the space segment charges, it may prove advantageous to adopt the lowercost system as soon as possible. In addition, the TDMA system offers significant long-term advantages of low-cost expansion and the ability to reconfigure the system with minimal or no loss of traffic.     

TCM／8PSK／IDR与QPSK／IDR卫星载波特性比较

介绍了ＴＣＭ／８ＰＳＫ／ＩＤＲ和ＱＰＳＫ／ＩＤＲ的工作方式以及主要传输参数,就两者对卫星转发器频带和功率利用率进行了比较;提出了今后国内卫星通信网在现仍体制下采用ＴＣＭ／８ＰＳＫ／ＩＤＲ取代ＱＰＳＫ／ＩＤＲ的建议。     

Technical and economic impact of the use of standard-B earth stations in the intelsat system

More than 20 years after the INTELSAT system started up, satellite technology developments have led to considerable changes in the world-wide international satellite transmission system. This evolution and the present capabilities offered by digital technologies make it possible to reassess the potential cost advantages of standard-B earth stations over a wider portion of international telephone transmission routes. This paper addresses the technical and economic issues raised by the characteristics of the present and planned INTELSAT satellites, together with the current capabilities of digital techniques (forward error correction, low rate encoding, time and frequency division multiple access). The foreseeable impact of the use of such techniques on overall satellite telephone transmission costs is also presented, and compared with that forecasted for fibre optic cable circuits.     

Analytical modelling and software implementation of synthetic aperture radars

Synthetic aperture radar (SAR) imaging systems are a complement to passive remote sensing. However, the process of image formation is so complex that the final image in the system is formed only after three basic steps: raw data acquisition, forming the signal and the image space. In addition, there are various factors that are involved in the information recorded by SAR within the system and outside the system, such as radar, platform, processing algorithm, imaging region and channel. Each of these factors has been formed by many parameters and this issue adds to the complexity of the behaviour of SAR. Therefore, due to the complexity, providing a model that describes how the SAR imaging system works is highly important. In this paper, the performance of SAR in the image formation section is analytically modelled at first, and then implemented as software. Raw data acquisition is performed in CST software and the signal and image formation are performed in MATLAB software. This implementation provides many abilities, such as better interpretation of SAR images, simulating the effect of the important parameters in SAR images, etc.     

手机软件系统的研究与开发

首先介绍了研究手机软件系统的背景和意义,然后阐述了现状和发展前景,最后简单地介绍了基于Java的手机系统的开发环境与系统功能。     

高级计划系统在PCB企业管理中的应用

随着PCB产业的不断发展,PCB企业之间的竞争日趋激烈,客户对交货期的需求越来越短。传统的ERP无法满足自动精细地制定生产计划,而只能依靠人工排产,导致交货期延误、人工成本提高、生产资源浪费等诸多问题,严重影响了企业声誉和竞争力。APS作为一种新兴的企业生产管理模式,将有效解决这一问题,成为PCB企业成长的一大助力。文章对APS系统作了简要的介绍,并讨论了其在PCB企业中应用的优势及导入方式。     

探索性软件测试方法及其在嵌入式系统中的应用

探索性软件测试发挥测试人员经验和创造性,强调软件测试各阶段的同时性,并利用测试学习被测系统,已形成应用体系并在工业界成功运用。将探索性测试技术应用于嵌入式系统软件测试,是解决测试时间紧、任务重、软件文档不完备等现实问题的有吸引力的方法。然而,嵌入式系统测试要求严格的软件测试管理流程和文档,并需对测试执行进行有效评价,这些要求在探索性测试中被弱化。调研和综述探索性测试技术,分析探索性测试技术与嵌入式系统软件测试体系的关联和冲突,是将探索性测试在嵌入式软件测试中的恰当运用的关键。以此为基础,对探索性测试在嵌入式系统软件测试中的应用模型提出了建议,并对应用中的问题和后续研究进行了讨论和展望。     

基于Android平台的软件加固方案的设计与实现

本文在深入分析Android的系统架构、软件结构及其执行机制的基础上,提出和实现了一种基于classes.dex文件动态加载的Android软件加固方案,实现软件关键代码的隐藏,可以有效地对抗各种针对Android软件的逆向工程攻击。     

模式在分布式软件系统中的应用研究

基于网络的分布式系统除了要进行基本的网络通信，还要处理复杂的服务访问配置和事件以及对高强度的并发和同步进行有效控制。这样才能满足其自身的基本性能要求，如：稳定性，资源共享，位置透明性，负载平衡等等。这也决定了开发高效的、健壮的、可扩展的又用得起的分布式应用程序是极其困难的。而强调复用的“模式”理论给软件系统带来的正是这些优良的特性；用模式生成分布式系统软件的体系结构或框架，不但可以提高分布式系统的性能，也有利于系统的开发和维护。     

软件生命周期中的信息安全管理

信息安全越来越受到重视,而数据或多或少地存在于系统之中,为了确保系统和数据的安全,信息安全策略和思想就必须融入到软件生命周期中去,信息安全也成为软件质量的一个重要组成部分。在当前流行的信息安全评价体系中,无不直接或间接涉及到软件生命周期中的信息安全管理问题,而各个评价体系有各有侧重,本文综合各评价体系的要求,总结为九个方面,就如何全面地将信息安全管理融入到软件生命周期中,以满足企业自身或第三方评价需要提出了设计和实施建议。     

现代软件工程在现代软件开发中的合理应用探究

随着社会经济的发展和科学技术水平的提高,计算机技术和信息技术在人们生产生活中的运用越来越广泛,计算机技术和信息技术是依靠软件进行系统运行的先进的科学技术,而现代软件的整体结构和特点影响了现代软件工程在现代软件开发中的应用,例如有些软件的开发,使用传统一般的软件工程方法比较科学合理,另外有些现代软件开发,则可以兼用传统的软件工程方法和现代的软件工程方法,因此必须要根据具体情况合理的进行选择,不能盲目统一适用其中一种或几种方法。     

关于建设开发软件过程软件项目管理的重要性探析

由于在软件项目管理过程当中保持一定的科学性,这可以做到有助于将软件开发人员的个人能力想企业开发能力转化。本文在此背景下,通过对软件项目管理重要性的阐述,随后对于软件项目管理要素与原则实施相应的总结,最后对建设开发软件过程当中软件项目管理的重要性实施相应的探讨。     

软件密钥托管加密系统中的一个问题及其修正

指出文献[1]建立的基于RSA的软件密钥恢复系统方案中存在的一个问题，并针对该方案给出避免这个问题发生的两种修正模式。     

系统软件开发过程中的软件工程技术

随着Internet的发展,应用系统也逐渐发生了改变,应用软件和系统软件逐渐向着智能化的方向发展。软件开发作为软件技术的基础,其开发方式决定着软件系统的结构和功能,与传统的软件相比,应用系统更符合现代市场需求。那么,软件的开发又是如何运作的,在开发过程中运用到哪些技术？针对这些问题,文章将重点探讨应用软件与传统软件的区别,分析软件工程中的模型设计和项目管理,从设计开发层面介绍了系统软件开发过程中的软件工程技术。     

软件工程方法在软件开发中的应用研究

为了适应时代的发展要求,需要做好软件工程的研究工作,开发出更多性能可靠的软件,加快我国经济社会的建设步伐。软件的有效开发,依赖于各种科学的方法,可以为相关问题的有效解决提供可靠的工作思路。软件工程包含着许多丰富的知识,在相对比较成熟的理论体系及各种宝贵的实践经验的支持下,正在影响着社会各行业长期稳定的发展。将软件工程方法应用于软件开发过程中,可以完善开发软件功能,增强这些软件的实际作用效果。因此,技术人员需要对软件工程方法有着必要地了解,结合软件开发的实际需求合理地运用。这些方法,最大限度地增强软件的适用性。本文将对软件工程方法在软件开发中的应用进行必要的研究。     

软件超市授权下载机制对比及其改进方案

在现有的软件超市平台中,授权机制不能避免无限制地分散合法下栽的软件,在此对此提出修正方案,对不同的下载软件设计出不同的流程,这意味攻击者不易开发出给一般人使用的通用工具,这样就可以增加软件的存活时间,而这也刚好解决了软件超市所出售软件生命周期短暂的问题。     

船用嵌入式软件可靠性及其参数研究

对船用嵌入式软件可靠性进行了研究，结合其总体特点，分析了不同研制阶段嵌入式软件的特点，进而指出了其可靠性的特点；提出了其可靠性参数选取与确定的原则和依据，并对其可靠性参数进行了定义与计算，注意到各参数的相关性和一致性，获得了船用嵌入式软件可靠性参数体系。     

传输网络光缆物理路由的规划

光传输网络的突出优势就是组网,自愈环是其主要拓扑结构,网络具有自愈保护功能。本地传输网络一般按骨干层、汇聚层和接入层的功能结构组织,在层次网络结构中,如何组织光缆路由。本文利用分枝限界法解决了自愈环光缆路由的选择问题,提出了分层网络光缆路由规划的数学模型。