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。

基于达到达到达到的信号发生器的源程序-Digital baseband signal transmission is a digital communications system, an important component. In digital communication, there are some occasions, may from time through the carrier modulation and demodulation process, the base-band signal for direct transmission. AMI code signal using alternating inversion, there may be four to zero with the phenomenon, which is not conducive to the receiving end of the timing signal extraction. The HDB3 code because of its non-DC components, low-frequency components, and even a small number of 0 up to more than three characteristics, while the timing signal recovery is very favorable, and has become CCITT Association recommended one of baseband transmission pattern. In this paper the use of VHDL language for data transmission system in the HDB3 encoder has been designed. Based on the signal generator to achieve to reach to reach the source