The Application Of Wavelet Transform In Signal Analyzing Technology To Pipeline Magnetic Flux Leakage Detecting

Defect discriminating is an important part in pipeline magnetic flux leakage (MFL) detecting, and to realize intelligent defect discriminating is the final intent of MFL detecting. The paper presents the significance of pipeline magnetic flux leakage detecting technology developing and defect discriminating technology developing. By comparing the different methods of signal analyzing, wavelet transform is selected as the main studying tool for the project.Firstly, the basic theory of MFL detecting together with the structure and the working procedure of pipeline MFL detecting instrument are introduced. Then it briefly describes the finite element analysis software ANSYS on it's application in this task.Secondly, it gives out the basic theory of wavelet transform in detail, concluding multi-resolution analysis (MRA) and decompose-reconstruct arithmetic of Mallat. Subsequently, using the focusing character of wavelet transform in analyzing signal, it recommends the theory of testing signal singularity and the route of analyzing pipeline MFL signal by wavelet transform. Then, compared the result with Fourier transform, wavelet transform's superiority and validity are validated in analyzing pipeline MFL signal.Lastly, the paper introduces wavelet package transform and its application. Wavelet package transform grows on the basis of wavelet transform. Its most excellence is to adjustably produce a best base as a token to signal according to different signal. In term of this theory, we decompose some simulate signal and pipeline MFL signal by wavelet package transform. Then select the best wavelet package base out of the decomposed coefficient and figure the brickwork of the best base on the relevant position in time-frequency plane showing the strong or weak of every coefficient. As a result, the time-frequency structure of signal analyzed is relatively visually represented; that is to say, an anticipative result achieves.The success of this project plays an important role to the developing of pipeline MFL detecting technology. Through it, we can master lots of defectMFL signal's c character and its distributing rules. And it can establish a foundation for pipeline MFL signal processing and intelligent defect discriminating.