Time-Delay Estimation of Ultrasonic Testing Signals by a Combination of Cross Correlation and Response Surface Method

Most ultrasonic testing applications are based on the measurement of time delay of received echoes. One popular technique for time-delay estimation is the cross-correlation technique. Various techniques are currently being used to improve the performance of cross-correlation. In this paper, the response surface method (RSM) is used to improve the accuracy of the cross-correlation technique in measuring the time delay of ultrasonic echoes, in particular at low signal-to-noise ratios (SNR). To demonstrate the ability of RSM, we have applied the technique to modeled signals having different SNRs. The results are then compared with other commonly used techniques, such as interpolation. It is concluded that RSM could be a good candidate for improving the results obtained by the cross-correlation technique.