中文说明：前段时间由于项目需要，学习了下如何提取信号包络线的方法，主要是在希尔伯特变换之上，添加了优化算法，采用三次抽样的方法使包络线变得平滑。
English Description：
Some time ago, due to the needs of the project, I learned how to extract the signal envelope, mainly in the Hilbert transform, adding optimization algorithm, using the method of three sampling to make the envelope smooth.