Signal processing in ultrasonic testing of coarse grain materials

In the ultrasonic testing of coarse grain materials, signal-to-noise ratio (SNR) is very low due to the serious structure noise. To enhance the SNR and reliability of ultrasonic testing of coarse grain materials, many works have been done in the application of digital signal processing methods, including signal averaging, filtering, convolution, spectrum analysis and time-frequency analysis, to the testing practice in the past year. Being a time-frequency analysis process, wavelet analysis has a auto-adaptive band, and is suitable to deal with the ultrasonic defect signal that has time-variable property. The utilization of wavelet analysis in signal processing of coarse grain materials leading to much more abundant information than normal program, and SNR is strengthened concretely