Improved time domain ultrasonic signal synthetic aperture algorithm

Abstract

The invention discloses an improved time domain ultrasonic signal synthetic aperture algorithm. The algorithm comprises the steps that (1) firstly, a head wave acoustic time method is used to determine the approximate distribution of test piece defects, and the head wave acoustic time method can adopt a reflection method or a transmission method to detect a test piece; (2) secondly, the distribution position of the defects is imaged by means of synthetic aperture focusing; a probe is used to move along a detection line; each time the probe steps a fixed displacement, after each time the probesteps a fixed displacement, an echo signal is collected, numbered and stored; and (3) finally, a focusing algorithm is implemented; the echo signal of each step position is processed; according to a vector addition and synthesis method, delayed superposition of the focusing radius with a smaller number of apertures on the left and right is carried out to acquire a beam with good directivity. According to the invention, possible errors during signal transmission and receiving are reduced, and the accuracy of an imaging result is improved.

Description

technical field [0001] The invention relates to the field of ultrasonic detection, in particular to an improved time-domain ultrasonic signal synthesis aperture algorithm. Background technique [0002] In all ultrasonic testing, it is necessary to determine the defect target qualitatively or quantitatively, and the position distribution of the defect target is what the inspector most hopes to obtain. In the research of ultrasonic imaging, the spatial position information of the internal defect target is included in the echo, and after processing the imaging, this information can be presented as a visual image target. Since it is an image, the parameter of image resolution becomes very important for imaging results. The resolution of multiple point targets in the image directly determines the resolution of the imaging system. The lateral resolution of the system can be expressed as the resolution of two point targets in the same distance direction but in different directions...

AI Technical Summary

Problems solved by technology

[0024] In the synthetic aperture focusing imaging test, it is theoretically required that multiple probes form a "large aperture" probe to image the defect position, which requires very high consistency in the physical properties of the probes. If there are differences in physical properties, it will inevitably Affect the ultrasonic signals it transmits and receives, so that cumulative errors will be generated when the echo is demonstrated and superimposed in the later stage, which will affect the detection accuracy

[0025] In addition, in the traditional SAFT algorithm of synthetic aperture detection (ultrasonic signal synthetic aperture algorithm), the focus on the defect point is formed by the superposition of all the echoes irradiated to the defect point. Improve the focus amplitude of the defect point to make the defect point more prominent, but due to the delay and consistency adjustment of the multi-channel signals in the early stage, the superimposed imaging result of the focus point will be extended horizontally, that is, the lateral size will become larger

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