小波滤波在超声管外测压回波处理中的应用

超声测压过程中信号受到噪声的干扰,使得回波信号质量较差。为提取后续特征,需对回波信号进行处理。而小波具有"变焦距"特性,在时域和频域中具有良好的局部分析能力,适合于超声等非平稳信号处理。在超声反射回波的数学模型基础上,利用小波滤波方法对超声信号进行预处理,提取强噪声背景中的弱回波信号。仿真及实验表明,用小波滤波能够有效抑制噪声,提高信噪比,且该方法原理简单,易于实现,为进一步研究超声管外测压奠定了基础。

Application of Wavelet Filtering to Echo Processing in Ultrasonic Pressure Measuring Outside Pipe

In ultrasonic pressure measuring outside pipe,echo signal is disturbed by noise.Therefore,the quality of echo is poor,and echo signal should be processed for extracting its features.The wavelet transform has a good performance of local analyzing in both time domain and frequency domain.It is fit for analyzing non-stationary signals,such as ultrasonic signal.This paper attempts to pre-process ultrasonic signal by wavelet filtering based on the mathematical model of the ultrasonic echo,extracts weak echoes from signal with high noise background.The simulation and the experimental results show that wavelet filtering could depress noise well,improve signal-to-noise ratio.It builds the foundation for ultrasonic pressure measuring outside pipe.