说明：  数字下变频（DDC）在如今基于软件无线电的架构中对系统的整体性能决定性的影响，代码为基于Matlab的4通道DDC程序，程序中可以根据需要调节滤波器等参数评估DDC的性能对于使用FPGA实现DDC有较大的参考价值
(Digital down conversion (DDC) in today' s architecture based on software radio system a decisive impact on the overall performance of the code for the 4-channel DDC Matlab-based program, the program can be adjusted according to filter parameters such as the use of performance assessment FPGA DDC DDC has achieved great reference value)