中文摘要：

根据适用于激励超声导波的信号的特征，在改进直接数字频率合成器（DDS）结构的基础上，运用DSP＋FPGA等工具设计出适合导波检测用的任意波形脉冲激励源。该激励源可根据实际检测条件调整激励波形的类型且激励信号中心频率、周期数、幅值、重复频率等参数均可设置。经实验验证，此激励源能生成导波检测所需要的各种波形信号，且能扩展应用于导波聚焦检测系统。该激励源具有易于生成各种脉冲激励信号、电路结构简洁、扩展性强等优点。

英文摘要：

By integrating the DSP and FPGA technology, an arbitrary waveform pulse excitation circuit for excit- ing ultrasonic guided waves which is built on the basis of improved direct digital synthesis （DDS） is presented. The pulse excitation circuit can perfectly generate the desired pulse signal with the characteristics of the typical pulse signal used in the guided wave technology. Meanwhile, the presented pulse excitation circuit can generate the right signal type for different inspection conditions. The parameters of the generated pulse signal, such as central frequency, cycle number, amplitude, repetition frequency, can be set as required. Experimental results prove that the pulse excitation circuit can generate desired signal type with a good accuracy to fit the require- ments in practice and be used for focusing detection system in guided wave. The whole circuit is easy to gener- ate the desired pulse signal, is concisely designed and has a strong expandability.