The xDSL -transmitting environments are investigated The line codes in common used by XDSL such as PAM, CAP, QAM and DMT are discussed.

• 对xDSL常用线 路编码脉冲幅度调制 （PAM） 无载波幅相调制（CAP） 正交幅度调制（QAM）和 离散多音频eq等进行了分析；