基于FPGA的超声导波信号发生器设计研究

Research on Design of Ultrasonic Guided Wave Signal Generator Based on FPGA

为减少超声导波检测中频散现象给检测管道工作带来的不利影响,提出了一种针对管道的超声导波激励信号源的设计方法,采用直接数字合成(DDS)技术,基于现场可编程门阵列(FPGA)、高速数模转换器器件AD9708和运算放大器ADA4870等器件,设计出专门用于激励超声导波的汉宁窗调制单音频信号的窄带脉冲信号发生器,该信号发生器可实现汉宁窗的宽度可调,汉宁窗调制下的单音频信号频率可调的功能。实验结果表明该信号发生器的硬件与软件的设计合理,激励信号的各项参数符合要求,并且相比其他方法,操作方便,节约了操作时间,提高了检测的精度与效率。

In order to reduce the adverse effects of dispersive phenomena in pipeline ultrasonic guided wave inspection,a design method of ultrasonic guided wave excitation signal source for the pipe is presented.In the proposed design method,Direct Digital Synthesizer(DDS) technology,Field Programmable Gate Array(FPGA),high speed digital-analog convert device AD9708,operational amplifier ADA4870 and other devices are used to design a narrow-band signal generator which can stimulate the single acoustic frequency signal of ultrasonic guided waves modulated by Hanning window.The proposed designed generator can adjust the width of Hanning window,and the frequency of single acoustic frequency signal.The experiment results show that the hardware and software design of the signal generator is reasonable,and the parameters of the excitation signal meet the requirements.Compared with the other methods,the signal generator is easy to operate,saves operation time,improves the accuracy and efficiency of detection.