基于AD9854的超声导波激励电路设计

为解决超声导波激励信号频率单一问题,设计了一种基于直接数字频率合成器(DDS)AD9854的宽频超声导波信号激励电路。在激励电路设计过程中,激励信号是由DDS利用正弦信号的相位与时间线性变化的特性,通过查询芯片内部存储的正弦信号表来实现频率的合成,并快速生成Chirp信号。采用椭圆低通滤波器消除DDS的杂散干扰,采用电压放大电路和功率放大电路进行信号两级放大,实现±25 V、100 kHz^1 MHz的Chirp信号输出。实验结果表明,超声导波激励电路软硬件设计合理,不仅能激励出超声导波检测所需要的宽频Chirp信号,还能明显区分出铝板上有无腐蚀缺陷,适用于激励多种不同中心频率的超声导波传感器。

Ultrasonic Guided Waves Excitation Circuit Based on AD9854

In order to solve the problem of single frequency of ultrasonic guided waves excitation signal,a broadband ultrasonic guided waves signal excitation circuit based on direct-digital synthesizer (DDS) AD9854 is designed.The excitation signal was a Chirp signal generated by the DDS.The DDS used the characteristics of the linear change of phase and time of the sinusoidal signal to achieve frequency synthesis by querying the sinusoidal signal table stored in the chip.The elliptical low-pass filter was used to eliminate the spurious interference of the DDS,and the voltage amplification circuit and the power amplification circuit were used for the two-stage amplification of the signal to realize the Chirp signal output of ±25 V,100 kHz~1 MHz.The experimental results show that the software and hardware design of the ultrasonic guided waves excitation circuit is reasonable,which can not only stimulate the broadband Chirp signal required for ultrasonic guided waves detection,but also clearly distinguish whether there are corrosion defects on the aluminum plate.It is suitable for exciting a variety of ultrasonic guided wave sensors with different center frequencies.