已调制信号计算其普相关密度，FIR 底通和带通滤波器和IIR 底通和带通滤波器，非常适合计算机视觉方面的研究使用。- Modulated signals to calculate its density Pu-related, Bottom-pass and band-pass FIR and IIR filter bottom pass and band-pass filter, Very suitable for the study using computer vision.