Research on detection method of electromagnetic ultrasonic signal based on FPGA

The transduction efficiency of an electromagnetic acoustic transducer (EMAT) is rather low, while the receiving coil of the transducer is very sensitive to the environment noise, which leads to a low signal-to-noise ratio (SNR) of the received signal. Consequently, the receiving circuit of an EMAT detection system must have a strong ability of weak signal detection under a noisy environment. To improve the SNR of the received signal and to efficiently extract echoes reflected by defects, we propose a detecting method combining wavelet transform and FIR filter. Feasibility and efficiency of the method is verified by experiments. The proposed algorithm is realized by FPGA, which can significantly improve the detecting efficiency, and reduce the volume as well as the cost of the detection system.