数字电视条件接收系统的研究

【作者】 李寿强；

【导师】 李广军；

【作者基本信息】 电子科技大学 ， 电子与通信工程， 2005， 硕士

【摘要】 数字视频广播(DVB)系统不但能够提供数字化广播节目，而且能够提供大量的增值服务，给传统的广播行业带来了新的发展机会。条件接收系统(CAS)是DVB系统实现增值的核心，能够提供有效的系统管理和用户控制。它集多种先进技术于一身，诸如：系统调度管理、网络技术、数字压缩编码、加解扰算法、加解密算法、复用器技术、调制解调技术、机顶盒技术、智能卡技术等，同时也涉及到用户管理、节目管理、收费管理等数据库应用技术。 CAS在国外起步较早，现在已有多家知名CAS提供商，在全世界范围内运营，提供比较完善的服务。随着数字化时代的到来，目前我国也出现了多家CAS提供商，个别CAS在国内某些有线电视台也己经开始运营，但国内CAS还需要经过很长一段时间的检验才能够逐渐发展完备和成熟。 本文在对CAS的各个方面做简明和深入综述的基础上，主要完成了以下三部分工作。 第一部分介绍了数字电视条件接收相关的部分关键技术，包括MPEG—2、DVB的相关标准规范、加解密技术、DVB同密和多密技术。 第二部分进行CA系统架构的设计和实现。本论文采用DVB同密方案和三层加密的密钥体系结构，基于Microsoft．NET平台实现了CAS的基本功能。具体来讲，包括密钥体系结构的设计，ECM和EMM信息结构的设计，CA系统具体结构及其接口的设计等。根据设计方案，用C#编程语言实现了一个基本的CAS软件。 第三部分进行系统的测试。组建了一个基本的测试系统，并对测试结果进行了简要的分析。经过测试证实，本论文中设计的系统具备了CAS的基本功能，并且其接口符合DVB标准的有关规定。在最后，本论文提出了系统以后升级和完善的方向。更多还原

【Abstract】 Digital video broadcasting system(DVB), which can provide not only many digital programs, but also variety of services, brings valuable opportunities to the traditional broadcast industry. Conditional access system (CAS) is the key to realize the increment of the DVB system and provides effective system management and subscriber control. It covers many advanced techniques such as system-scheduling management, network, digital coding and decoding, scrambling and descrambling, encrypting and decrypting, multiplexing, modulating and demodulating, set-top box, smart card and some practical database techniques, for example program management, subscriber management and charging management.CAS appeared firstly in western countries, and at present, there are many mature CAS providers who provide complete solutions with various services throughout the world. Facing the impending of the digitalized era, some CAS providers have appeared in China and put some of their products into practical implementation, all of which are immature and should be checked by time.This paper is based on the concise and deep-going survey of CAS and finished the following three parts.In the first part, this dissertation introduces some digital TV CAS key technologies, such as criteria on MPEG-2 and DVB, encryption and de-encryption, simulcrypt and multicrypt etc.In the second part, this dissertation carries on the design of CA system architecture and realize. This dissertation is adopted with the DVB simulcrypt technology and three layers of key systems . The basic function of CAS is realized based on Microsoft .NET Framework. Particularly, this dissertation has designed several following parts: the structure of ECM and EMM,the architecture of key systems,the concrete structrure of CAS and the interface each other,etc. According to the design, the software with basic function of CAS is realized with C# language .In the third part, this dissertation carries on the test of CAS. A basic system will更多还原