该程序采用多相分解方式实现的抽取器滤波器，该抽取器的运行速度要比向下采样器的通常FIR滤波器的速度快R倍。-The program uses polyphase decomposition way to achieve the decimation filter, the speed of the extractor runs faster than the down sampler of the FIR filter is generally faster R times.