数字基带信号的传输是数字通信系统的重要组成部分。在数字通信中，有些场合可不经过载波调制和解调过程，而对基带信号进行直接传输。HDB3码的作用是对数字基带信号进行编码，便于在接收端对定时分量的提取。-Digital baseband signal transmission is an important part of digital communication system. In digital communication, some occasions without carrier modulation and demodulation process, and to direct transmission baseband signal. HDB3 code is used to encode digital baseband signal, facilitate at the receiving end of timing component extraction.