Event Title

High-Order Spectra-Based Deconvolution of Ultrasonic NDT Signals for Defect Identification

Location

Snowbird, UT, USA

Start Date

1-1-1999 12:00 AM

Description

Pulse echo signals measured in ultrasonic NDT include the effect of the measuring systems, the propagation paths taken by the ultrasonic waves, and are corrupted by additive noise. For instance, the ultrasonic signals for a particular reflector recorded under the same conditions, but using different transducers can be quiet different. This leads to the difficulty of comparing and analyzing signals particularly in automated defect identification systems employing different transducers. Generally, it is assumed that the measured pulse echo is obtained by linearly convolving the defect impulse response with the measured system response. Deconvolution operation therefore, seeks to undo the effect of the convolution and extract the defect impulse response which is an essential step for the identification and characterization of defects. Conventional deconvolution techniques such as least square, Wiener filter, and minimum variance deconvolution [1] are based on a priori knowledge of second-order statistics (SOS) of the noise and the input signal. In practice however, ultrasonic pulse echo signals are found to be non-minimum phase systems and the acoustic noise due to scattering from the grains inside the propagation medium does not have a readily known statistic [2]. SOS-based deconvolution techniques, being phase-blind cannot therefore, accurately estimate the defect impulse response.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

18A

Chapter

Chapter 3: Simulations, Signal Processing, Tomography, and Holography

Section

Signal Processing and Analysis

Pages

727-734

DOI

10.1007/978-1-4615-4791-4_93

Language

en

File Format

application/pdf

This document is currently not available here.

Share

COinS
 
Jan 1st, 12:00 AM

High-Order Spectra-Based Deconvolution of Ultrasonic NDT Signals for Defect Identification

Snowbird, UT, USA

Pulse echo signals measured in ultrasonic NDT include the effect of the measuring systems, the propagation paths taken by the ultrasonic waves, and are corrupted by additive noise. For instance, the ultrasonic signals for a particular reflector recorded under the same conditions, but using different transducers can be quiet different. This leads to the difficulty of comparing and analyzing signals particularly in automated defect identification systems employing different transducers. Generally, it is assumed that the measured pulse echo is obtained by linearly convolving the defect impulse response with the measured system response. Deconvolution operation therefore, seeks to undo the effect of the convolution and extract the defect impulse response which is an essential step for the identification and characterization of defects. Conventional deconvolution techniques such as least square, Wiener filter, and minimum variance deconvolution [1] are based on a priori knowledge of second-order statistics (SOS) of the noise and the input signal. In practice however, ultrasonic pulse echo signals are found to be non-minimum phase systems and the acoustic noise due to scattering from the grains inside the propagation medium does not have a readily known statistic [2]. SOS-based deconvolution techniques, being phase-blind cannot therefore, accurately estimate the defect impulse response.