舰船钛合金超声检测信号模型及模极大值小波去噪算法分析

An ultrasonic testing model for titanium alloy used in armada and its wavelet transform denoising algorithm based on modulus maximum

针对舰船用钛合金超声检测信号中普遍存在的材料散射噪声过大的现象,结合钛合金超声检测信号与散射噪声信号的产生特点,构造了一组信号模型,并提出了基于小波分解的一种改进的模极大值去噪算法。该算法利用小波分解中的低频系数来确定信号位置,在高频各尺度系数的对应位置寻找相应的频率信息,以达到提取信号去除噪声的目的。实例分析表明,该模型能基本反映超声检测信号的特点,而且此算法对TA2钛合金超声检测信号去噪效果比较理想。

The ultrasonic testing signal of titanium alloy used in armada is always immingled with the scattering noise. For the phenomena, this paper presents a kind of signal model of ultrasonic testing for titanium alloy and a wavelet transform denoising algorithm based on modulus maximum. The characters on producing mode and wavelet transform of noise and signal are discussed. The processing of the algorithm is followed:firstly, ascertain the location of signal in the low frequency coefficient of wavelet transform; secondly, find corresponding frequency information in the high frequency coefficient; thirdly, reconstruct the signal through inverse wavelet transform. Examples prove that the model can reflect the character of the ultrasonic signal and noise signal correctly, and the result of the denoising using this algorithm for TA2 titanium is satisfaction.