在分析高效宽频带变频系统的基础上提出一种可以把变频部分与多种调制方式灵活结合在一起的方法，并以QAM调制为例，给出具体算法．分析结果表明，该方法降低了对处理速率的要求，提高了处理能力-In order to design an efficient and flexible DDC／DUC system，this paper combined the signal processing of DDC／DUC with QAM system and presented a new method based on the analysis of this efficient broadband DDC／DUC system．QAM modulation was taken for example，and a detailed algorithm of a channel system with 0～30 MHz and 60 channels QAM was presented