超声换能器时频域特性校准系统研究与实现

针对我国超声探伤仪换能器校准数字化程度较低的现状，深入分析国内外校准规范后，提出基于数字信号处理技术，实现换能器时域及频域性能自动校准的方法。设计并构建了超声换能器自动校准系统；对超声回波信号的分析，时域上利用了经验模态分解算法进行预处理去趋势项，同时提出从一列多次超声回波中获取首次回波的提取方法；频域上，利用数字频谱分析技术及加窗方法，对超声换能器首次回波进行频域特性分析；通过实际校准实验，整理并分析了若干提高检测可靠性的关键因素。实验结果表明，超声回波分析方法的实时性及可靠性较高，硬件结构的设计较为合理。

Research and implementation of frequency domain characteristic calibration system for ultrasonic transducer

In view of current situation of the Ultrasonic Flaw Detector transducer ’s low degree digitization ,following in‐depth analysis of domestic and international calibration standards ,proposed a method based on signal processing technology to automatic calibrate transducer performance both in time domain and frequency domain .Designed and built an automatic calibration system of ultrasound transducer ;after analysis of ultrasonic echoes ,used the EMD algorithm to do the preprocessing to trend item in time domain ,and proposed method to extract the first echo from a list of multiple ultrasonic echo ;then analyzed the frequency domain characteristics of the first echo from ultrasonic transducer in the use of digital spectrum analysis technology and window‐added method in the frequency domain ;through practical calibrate test ,collated and analyzed a number of key factors to improve the reliability of detection .Experimental results show that the method of Ultrasonic echo analysis has good Real‐Time Performance and reliability ,and the design of hardware structure is more reasonable .