A signal preprocessing method

Abstract

The invention discloses a signal preprocessing method, comprising steps: 1. Acquiring and synchronously uploading ultrasonic echo signals; 2. Determining wave peaks and troughs; 3. Eliminating extremum points; Value point time interval determination, division point judgment and sampling time determination of division point, signal division judgment, division point sorting and signal division; 5. Signal separation judgment and signal separation. The method of the present invention has simple steps, reasonable design, convenient implementation, and good use effect. Firstly, the judgment of the segmentation point and the determination of the sampling time of the segmentation point are realized by performing threshold judgment on the time interval of adjacent extreme points, and according to the determined number of segmentation points and Segment the ultrasonic echo signal at the sampling time of each segmentation point; then perform signal separation judgment and signal separation on each segmented signal, and separate the independent ultrasonic echo signals at the positions of multiple defects in the same ultrasonic echo signal Easy and quick separation.

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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