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阵列声波信号是典型的非线性、非平稳信号,Hilbert-Huang变换(HHT)是处理非平稳信号的一种比较新的时频分析方法。通过对信号进行经验模态分解(EMD)和对瞬时频率的求解,可以获得声波信号的时-频谱。其关键技术就是进行经验模态分解,任何非平稳的信号都可以分解为有限数目并且具有一定物理意义的固有模态函数。EMD方法可以理解为以声波信号极值特征尺度为度量的时频滤波过程。滤波器充分保留了声波信号本身的非线性和非平稳特征,在声波信号的滤波和去噪中具有很大的优势。文中介绍了HHT时频滤波的实现过程,并列举了一些声波测井波列实例,说明了该方法的有效性。
The array acoustic signal is a typical non-linear, non-stationary signal. Hilbert-Huang Transform (HHT) is a new time-frequency analysis method for non-stationary signals. The time-frequency spectrum of the acoustic signal can be obtained through the empirical mode decomposition (EMD) of the signal and the solution of the instantaneous frequency. The key technique is to decompose empirical mode, any non-stationary signal can be decomposed into a finite number and has some physical meaning of the inherent modal functions. The EMD method can be understood as a time-frequency filtering process taking the characteristic scale of the extremum of the acoustic signal as a measure. The filter fully preserves the non-linear and non-stationary characteristics of the acoustic signal itself, which has great advantages in the filtering and denoising of the acoustic signal. In this paper, the realization process of HHT time-frequency filtering is introduced, and some examples of acoustic wave trains are listed, which shows the effectiveness of this method.