Study on Signal Denoising in Casting Ultrasonic Testing Based on Translation Invariant

Interference noising originating from the ultrasonic testing defect signal seriously influences the accuracy of the signal extraction and defect location. A method based on the translation invariant discrete wavelet transform (TIDWT) wavelet shrinkage was proposed for signal extraction according to the characteristics of the casting defect ultrasonic signal. Both simulated and actual steel defect signals were tested. The results were compared with those of the traditional wavelet shrinkage estimate algorithm. The experiments show that Pesudo-Gibbs phenomenon can be suppressed efficiently. RMSE between the original signal and estimated one can be minished, SNR of estimated signal can also be improved. It is proved by the experiment that this method can denoise more effectively; the signal quality and performance parameters obtained by TIDWT is improved obviously