详细画出了时域和频域的相关图，是学习PCA特征提取的很好的学习资料，FIR 底通和带通滤波器和IIR 底通和带通滤波器。- Correlation diagram shown in detail the time domain and frequency domain, Is a good learning materials to learn PCA feature extraction, Bottom-pass and band-pass FIR and IIR filter bottom