本ETR描述了一种称为非对称数字用户线（ADSL）的传输技术。本报告定义了ADSL传输系统的要求和传输性能。ADSL允许在与模拟电话服务相同的单用户线上提供各种数字信道。ADSL系统包含多个数字通道。其中一些是全双工低速信道，另一些是单工高速信道。高速通道仅向客户场所的方向运输。该ETR基于ANSI T1。413[1]由ANSI委员会T1 E1提供。仅包含ANSI T1未涵盖的特定欧洲主题

This ETR describes a transmission technique called Asymmetric Digital Subscriber Line (ADSL). The requirements for the ADSL transmission sys tem and the transmission performance are defined in this report. ADSL allows the provision of a variety of digital channels on the same, single subscriber line as the analogue telephone service. An ADSL sy stem contains several digital channels. Some of them are full duplex l ow-speed channels and the others are simplex high-speed channels. The high-speed channels are transported only in the direction to the custo mer premises. This ETR is based on ANSI T1.413 [1] provided by the ANSI committee T1 E1.4 and contains only specific European topics not covered by ANSI T1