基于LabVIEW的时间反转超声检测系统的开发

Design of Time Reversal Ultrasonic Detection System Based on LabVIEW

摘要:

时间反转技术在超声无损检测中的应用非常广泛,它可以忽略介质的非均匀性及初始信号源的位置,能够在时间和空间上聚焦超声波,实现对介质缺陷的聚焦检测；基于LabVIEW图形化编程软件,结合计算机、信号发生器、示波器、超声换能器、GPIB等的使用,对超声检测系统实验平台进行了构建,实现了超声信号的发射、接收以及时间反转一系列的信号处理过程；系统工作过程中,采用了3种不同的时间反转技术:经典时间反转技术(time reversal:TR)、反向滤波技术(inverse filter:IF)及1位处理技术(1bit processing),来实现信号的聚焦,其中反向滤波处理技术取得的信号聚焦效果较好,信噪比较低,而运用1位时间反转技术可以有效增加聚焦信号的幅值,使幅值提高3.5 dB左右;实验验证该系统可以有效的实现时间反转超声检测过程中对信号的激励、接收、处理和存储等功能,有良好的精确性和适用性。

Abstract:

The application of time reversal technique in ultrasonic nondestructive testing is very extensive, which can focus ultrasonic waves in time and space and realize a flaw detection, regardless of the position of the initial source and of the heterogeneity of the medium. In this paper, with the combined application of LabVIEW, signal generator, oscilloscope, ultrasound transducer and GPIB, an acoustic detect testing system has been constructed which achieves some functions including signal generation, acquisition, time reversal processing, and so on. When the test system is working, three different kinds of time-reversal techniques can be chosen to focus the ultrasonic signal:Time Reversal (TR), Inverse Filter (IF) and 1Bit Processing (1 B).The technique of Inverse Filter (IF) has the best ability of localization and a lowest signal to noise ratio in the three techniques.The technique of 1Bit Processing can effectively increase the amplitude of the focusing signal,the amplitude can increase about 3.5 dB.The experiment results have verified that in the process of ultrasonic nondestructive testing the system can realize some functions:signal generation, acquisition, procession and storage and it has good accuracy and adaptability.