文中应用软件无线电思想对数字下变频器中的几个关键技术进行了研究,对下变频各个模块所涉及到的CIC、HB、FIR等关键算法进行了讨论、提炼与总结,应用matlab软件设计了下变频器中的CIC、HB、FIR滤波器等核心模块,并将各模块融为一体从软件实现的角度完成了对系统的搭建和功能仿真.仿真结果表明,系统实现了对中频信号的下变频处理且无失真现象,大大减少了软件无线电系统数宁信号处理的运算量和数据的存储量,极大地提高了系统的实时性.-The paper application software radio digital down converter in the thinking of several key technologies have been studied for the next conversion involved in each module to the CIC, HB, FIR and other key algorithms were discussed, refined and summarized the application of matlab software design downconverter in the CIC, HB, FIR filters and other core modules, and integration of various modules from the software point of complete structures and functions of the system simulation. The simulation results show that the system achieved the right under the IF signal Frequency processing and without distortion, thus greatly reducing the number of software-defined radio system, rather the amount of signal processing operations and data storage capacity, greatly improve the system in real time.