一、认识ADSL 随着通信和计算机技术的飞速发展,用户对电话、传真、多媒体通信、交互视频业务和高速数据等宽带业务提出了更高要求,因此采用新技术、加快宽带接入网的建设就显得非常迫切。 用户接入网是指从本地电话端局到用户之间的部分,又称用户环路,接入网提供各种从核心网到用户住宅设备的接入通道,用户接入可采用铜线、光纤、同轴电缆和无线等几种方式。上海市电话局拥有最丰富的铜线资源,合理充分利用这些资源,加快建设宽带接入网推动社会信息化进程的一项重要技术就是DSL技术(Digit Subscriber Loop数字用户线),包括ADSL(Asymmetrical Digital Subscriber Loop非对称数字用户线),HDSL(High bit-rate Digital Subscriber Loop高比特率数字用户线)、IDSL(ISDN Digital Subscriber Loop综合业务数字网式数字用户线)、SDSL(Symmetrical Digital Loop对称数字用 I. Understanding ADSL With the rapid development of communications and computer technology, users have put forward higher requirements on broadband services such as telephone, fax, multimedia communications, interactive video services and high-speed data. Therefore, adopting new technologies to speed up the construction of broadband access networks It is very urgent. User access network refers to the part from the local telephone end office to the user, also known as user loop, the access network provides a variety of access channels from the core network to the user’s residential equipment, the user access can be copper, Optical fiber, coaxial cable and wireless and other ways. Shanghai Telephone Office has the most abundant copper resources, reasonable use of these resources to speed up the construction of broadband access network to promote social information technology is an important technology DSL (Digit Subscriber Loop digital subscriber line), including ADSL (Asymmetrical Digital Subscriber Loop Asymmetric Digital Subscriber Line), HDSL (High bit-rate Digital Subscriber Loop), IDSL (ISDN Digital Subscriber Loop), Symmetrical Digital Loop Symmetric Digital use