基于经验模态分解的聚焦超声非线性声场检测

摘要

为精确检测聚焦超声声场中的谐波成分并得到谐波分布规律,开展了对聚焦超声非线性声场检测的研究,提出基于经验模态分解的聚焦超声谐波检测方法.首先对声场信号进行经验模态分解;然后利用噪声判断准则判断出固有模态函数(IMF)中的噪声分量,滤除噪声分量后将剩余的IMF分量予以重新组合;最后对新信号进行傅里叶变换,得到各次谐波的幅值.结果表明:它能较好地抑制噪声,相比于传统的检测方法可获得更平滑的谐波分布;该方法对开展谐波成像、医学超声检测具有重要意义.%For accurately measurement of harmonic component of the focused ultrasound field and obtain the distribution,the focused ultrasound harmonic detection method which based on EMD in research of focused ultrasound nonlinear acoustic field is presented.First,to analysis the sound signals by using EMD.Then,noise criterion included in IMF by noise criterion is determined.Finally,by using Fourier transform on new signals,the amplitude of each harmonic could be showed on the result.Compared with the traditional method FFT,the focused ultrasound nonlinear acoustic field detection method could effectively suppress the noise;through the result it could obtain smoother harmonic distribution.The new method would make contribution in harmonic imaging and medical ultrasound.