Signal-to-noise ratio enhancement based on wavelet filtering in ultrasonic testing.
In ultrasonic non-destructive testing of materials with a coarse-grained structure the scattering from the grains causes backscattering noise, which masks flaw echoes in the measured signal. Several filtering methods have been proposed for improving the signal-to-noise ratio. In this paper we present a comparative study of methods based on the wavelet transform. Experiments with stationary, discrete and wavelet packet de-noising are evaluated by means of signal-to-noise ratio enhancement. Measured and simulated ultrasonic signals are used to verify the proposed de-noising methods. For comparison, we use signal-to-noise ratio enhancement related to fault echo amplitudes and filtering efficiency specific for ultrasonic signals. The best results in our setup were achieved with the wavelet packet de-noising method.
Matz
Vaclav
V
Department of Measurement, Faculty of Electrical Engineering, Czech Technical University, 166 27 Prague 6, Czech Republic.
Smid
Radislav
R
Starman
Stanislav
S
Kreidl
Marcel
M
D000465:Algorithms; D007089:Image Enhancement / Q000379:methods*; D008420:Manufactured Materials / Q000032:analysis*; D008422:Materials Testing / Q000379:methods*; D012542:Scattering, Radiation; D012815:Signal Processing, Computer-Assisted; D014463:Ultrasonography / Q000379:methods*