Post Signal Processing of Ultrasonic Phased Array Inspection Data for Non-destructive Testing

In ultrasonic phased array non-destructive testing, the amplitude of the grain noise can be smaller than that of the echoes, and the grain noise can totally mask echoes characterizing faults. Several algorithms such as band pass filter, low pass filter, wiener deconvolution and wavelet have been employed to reduce the grain noise. In this paper, an actual S-scan detection image was obtained from a real time UT acquisition system, and a comparison of the suppressing grain noise performances of low pass filter and wavelet de-noising algorithm was displayed. The results show that the wavelet de-noising algorithm is better than other algorithms listed in this paper, and it can suppress the amplitude of grain noise from 100% to 20%. This approach is shown to offer significant performance advantages for NDE.