Digital Signal Processing System of Ultrasonic Signals

In general the ultrasonic testing is used for flaw detection and localization in tested materials. Flaws in materials are commonly characterized in measured ultrasonic signals by faults echoes. Ultrasonic signals measured on materials with coarse grained structure contain relative high level of noise. This undesirable part of ultrasonic signal should be reduced to make the fault echo detection process more accurate. The different method for the noise reduction have been proposed but implementation to the full ultrasonic system is still missing. This paper presents the implementation of the proposed digital signal processing (DSP) methods for ultrasonic noise reduction based on wavelet transform and Wiener filter. The presented system can be described as full automated ultrasonic system that offers the measurement and processing of ultrasonic signals with consequent visualization of flaws in 3D volume representation. The basic characteristics as Fourier transform, power spectral density and time segmentation of measured signals are also considered. The system is implemented in graphical user interface (GUI) in Matlab. The ultrasonic signal based on the equation considered the physical properties of measured material can be simulated and the proposed DSP algorithms are evaluated in terms of signal-to-noise ration enhancement. The DSP ultrasonic system consists of two main windows, one for the measurement and processing of signals and another for the simulation. The different representation of ultrasonic signal in A-scan, B-scan and C-scan can be displayed in the graphical window.