Time–frequency Wiener filtering for structural noise reduction

• Published in: Ultrasonics 2002-05, Vol.40 (1), p.259-261
• Main Authors: Izquierdo, M.A.G., Hernández, M.G., Graullera, O., Ullate, L.G.
• Format: Article
• Language: English
• Subjects: Acoustic signal processing; Acoustical measurements and instrumentation; Acoustics; Cross-disciplinary physics: materials science; rheology; Dispersive materials; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Materials science; Materials testing; Nondestructive testing: ultrasonic testing, photoacoustic testing; Physics; Signal processing; SNR enhancement; Ultrasonic NDE/NDT
• ISSN: 0041-624X; 1874-9968
• DOI: 10.1016/S0041-624X(02)00148-8

In order to enhance the defect in relation to background noise of large grained materials different algorithms have been developed. Wiener filtering techniques have proved to be efficient for the SNR enhancement of ultrasonic signals coming from highly scattering materials. These processing algorithms are based on designing a filter that has large gain at frequencies where the SNR is high and low gain at frequencies where SNR is small. However, this technique does not consider two important ultrasonic effects: the finite-time duration of the flaw UT signal coming from a defect and the distortion of the frequency components of the traveling wave-front due to the dispersion. In this work, a time–frequency Wiener filter is proposed that takes into account these two characteristics. Experimental results are presented, showing that the proposed time–frequency algorithm has an excellent performance on SNR enhancement.