Signal preprocessing method

Abstract

The invention discloses a signal preprocessing method. The signal preprocessing method comprises the following steps: 1, acquiring an ultrasonic echo signal and synchronously uploading; 2, determiningcrest and valley; 3, eliminating extreme points; 4, performing signal segmentation, wherein the process is as follows: determining the time interval of the adjacent extreme points, judging a segmentation point, determining the sampling time of the segmentation point, judging signal segmentation, sequencing the segmentation point and performing signal segmentation; 5, performing signal separationjudgment and signal separation. The method is simple in step, reasonable in design, convenient to implement and good in use effect; the time interval of the adjacent extreme points is subjected to threshold value judgment, segmentation point judgment and segmentation point sampling time determination are realized, the ultrasonic echo signal is segmented according to the determined segmentation point number and the sampling time of each segmentation point, each segmentation signal is subjected to signal separation judgment and signal separation, and independent ultrasonic echo signals at the position of a plurality of defects in the same ultrasonic echo signal are separated simply, conveniently and rapidly.

Description

technical field [0001] The invention belongs to the technical field of ultrasonic flaw detection, and in particular relates to a signal preprocessing method. Background technique [0002] Ultrasonic flaw detection (also known as ultrasonic testing or ultrasonic testing) is a non-destructive testing method that uses the difference in acoustic properties of materials and their defects to reflect the reflection of ultrasonic wave propagation and the energy change of penetration time to test the internal defects of materials. The principle of ultrasonic flaw detection is that the transmission loss of ultrasonic waves in solids is very small, and the detection depth is large. Since ultrasonic waves will reflect and refract on heterogeneous interfaces, especially if they cannot pass through gas-solid interfaces, if there are pores, cracks, Defects such as delamination (gas in the defect) or inclusions, when the ultrasonic wave (also called ultrasonic signal or ultrasonic signal) p...

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Problems solved by technology

[0008] In addition, when using the sparse decomposition method for signal denoising (also called signal extraction), the essence is to use the matching pursuit algorithm for signal extraction. Because in the matching pursuit algorithm, firstly, the selection of Gabor atoms has no physical meaning, and secondly, if If a wrong Gabor atom is selected in a certain iteration, the subsequent iteration process has to correct this error, resulting in mistracking and poor algorithm performance.

Moreover, according to the sparse signal representation theory, when the size of dictionary atoms is smaller than a threshold, due to the cumulative consistency constraints, the sparse representation is unstable and unreliable

Therefore, the existing sparse decomposition methods have many defects

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