An Examination of the Application of Wiener Filtering to Ultrasonic Scattering Amplitude Estimation

An A Priori Knowledge Based Wiener Filtering Approach to Ultrasonic Scattering Amplitude Estimation

“…Measurement of backscattered noise signals, estimation of noise power spectra, and generation of simulated flaw signals are discussed in Ref. 4.…”

“…A form of the Wiener filter which incorporates ~ priori flaw and noise information will now be considered [2,4]. The filter can be derived from a statistical approach where A(w) and n(w) are assumed to be uncorrelated, Gaussian random variables.…”

“…A frequency domain equation describing the flaw characterization experiment for a single transducer operating in the pulse-echo mode can be written as [2,4] where F(w) = R(w)A(w) + n(w) F Fast Fourier transform of the measured time domain signal R "Known" measurement system frequency response A Flaw scattering amplitude n Total noise = acoustic noise + electronic noise (1) The scattering amplitude estimation problem involves estimating A(w) given that F(w) has been measured in the presence of noise, n(w). The simplest approach to the estimation problem would be to ignore the noise and deconvolve the system response, R(w), out of the measured signal, F(w).…”

“…(2). The resultant scattering amplitude estimate, written as A(w) F(w)R*(w) jR(w)j2 + Q2 (3) represents the most widely used form of the Wiener filter as applied to the scattering amplitude estimation problem [1,4].…”

Creating Noise-Corrupted Flaw Signals for Ultrasonic Nondestructive Evaluation

“…In this paper, an approach is presented for creating "known flaw" noise-corrupted flaw signals which was frrst introduced by the authors in 1985 [8] and which has been used in a number of studies since that time [9][10][11]. Significant inspiration for this approach came from the work of Gray and Thompson in creating noise-free flaw signals [4,5].…”