希尔伯特变换的物理意义；注意：1）掌握希尔伯特变换的基本公式；2）了解在频率域，希尔伯特变换具有什么样的特性。 -The physical meaning of Hilbert transform Note: 1) to master the basic formula of Hilbert transform 2) to understand in the frequency domain, and Hilbert transform what kind of features.