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。采用AMI码的信号交替反转，有可能出现四连零现象，这不利于接收端的定时信号提取。而HDB3码因其无直流成份、低频成份少和连0个数最多不超过三个等特点，而对定时信号的恢复十分有利，并已成为CCITT协会推荐使用的基带传输码型之一。为此，本文利用VHDL语言对数据传输系统中的HDB3编码器进行了设计。-Digital baseband signal transmission is an important digital communication system components. In digital communications, some occasions may, after modulation and demodulation process, and on the base-band signals transmitted directly. AMI code using the turn signal inversion, there may be zero Silian phenomenon, which is not conducive to the receiving end of the timing signal extraction. HDB3 code and its non-DC components, and even less low-frequency components of 0 up to more than three the number of characteristics such as timing signals for the recovery of very favorable, and the Association has become the CCITT recommended base-band transmission-type, one code. In this paper, the use of VHDL language in the data transmission system HDB3 encoder has been designed.