有循环检测，周期性检测，结合PCA的尺度不变特征变换(SIFT)算法，用于信号特征提取、信号消噪，是学习PCA特征提取的很好的学习资料，添加噪声处理。- There are cycle detection, periodic testing, Combined with PCA scale invariant feature transform (SIFT) algorithm, For feature extraction, signal de-noising, Is a good learning materials to learn PCA feature extraction, Add noise processing.