ABSTRACT To improve the accuracy of the magnetic flux leakage (MFL) nondestructive testing in practical applications, it is very significant and key to deal with the detected MFL signals. As for the de-noising process of the MFL signals, a multilevel filtering approach based on wavelet de-noising combined with median filtering is proposed. By analyzing and comparing the de-noising properties of three wavelet families, i.e., Daubechies wavelet, Coiflets wavelet, and Symlets wavelet, two wavelet bases with the best de-noising performance are recognized and selected, namely sym6 and sym8 (the Symlets wavelet functions of order 6 and 8). Then, a new cascaded filter is constructed by combining sym6 and sym8 wavelets and cascading the median filtering method. An experimental platform is established to carry out the MFL testing, through the de-noising process for the measured MFL signals, and the results indicate that the proposed improved algorithm integrates with the merits of wavelet de-noising and median filtering. Compared with the traditional wavelet de-noising, the improved algorithm can not only improve the signal-to-noise ratio (SNR), but also reduce the de-noising error, resulting in enhancing signal quality to facilitate subsequent defect recognition.

中文翻译：

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基于小波滤波法的漏磁信号去噪

摘要 在实际应用中，要提高漏磁(MFL)无损检测的准确性，对检测到的漏磁信号进行处理是非常重要和关键的。针对MFL信号的去噪处理，提出了一种基于小波去噪与中值滤波相结合的多级滤波方法。通过分析比较 Daubechies 小波、Coiflets 小波和 Symlets 小波这三个小波族的去噪特性，识别并选择了去噪性能最好的两个小波基，即 sym6 和 sym8（Symlets 小波函数）。订单 6 和 8）。然后，结合sym6和sym8小波，级联中值滤波方法，构造了一个新的级联滤波器。建立实验平台进行MFL测试，通过对实测MFL信号的去噪处理，结果表明所提出的改进算法综合了小波去噪和中值滤波的优点。与传统小波去噪相比，改进后的算法不仅可以提高信噪比（SNR），还可以降低去噪误差，从而提高信号质量，便于后续缺陷识别。