A Pulse Compression Technique for Improving the Temporal Resolution of Ultrasonic Testing

摘要

It is difficult to interpret ultrasonic signals when the echoes that are reflected from the various target features overlap. In this paper, a pulse compression technique based on a combination of Wiener filtering and autoregressive (AR) spectral extrapolation is used to process ultrasonic signals to improve their temporal resolution. The influence of the AR order and the width of the frequency window in AR spectral extrapolation are discussed in detail, and optimal parameters are obtained. The technique is then applied to measure the size of the defects in a plate and discern two adjacent defects in a block using a phased array. It is shown that the widths of the defects in the plate were measured accurately and the two adjacent defects were distinguished well by the proposed technique.