title: Speckle reduction by energy time-frequency filtering.
abstract: Structural noise is a very important limitation to the visibility of flaw echoes in ultrasonic testing and evaluation of highly scattering materials. In order to enhance the signal-to-noise ratio, different algorithms have been developed. One of these techniques is based on filtering the spectrum low band of the received echo to obtain a significant improvement of the defect visibility. Based on this idea, in this work a new time-frequency technique is presented. In this method, block-processing autoregressive techniques are used to estimate the instantaneous center frequency of the traveling wave. From this information, a time-frequency filter is designed tuned at half the estimated instantaneous center frequency. Experimental results and the comparison with the non-time-frequency filtering technique are also included, showing that the proposed method has an excellent performance on SNR enhancement.
authors.affiliation: Departamento de Señales, Sistemas y Radiocomunicaciones, ETSI Telecomunicación, UPM, Ciudad Universitaria s/n, Arganda del Rey, Madrid 28040, Spain. izquierdo@gtsc.ssr.upm.es
authors.forename: M A G
authors.initials: MA
authors.lastname: Izquierdo
authors.forename: M G
authors.initials: MG
authors.lastname: Hernández
authors.forename: J J
authors.initials: JJ
authors.lastname: Anaya
authors.forename: O
authors.initials: O
authors.lastname: Martinez