| ABSTRACT: | APPLICATION OF PULSE COMPRESSION SIGNAL PROCESSING TECHNIQUES TO
ELECTROMAGNETIC ACOUSTIC TRANSDUCERS (EMATS) FOR NON-CONTACT
THICKNESS MEASUREMENTS AND IMAGING
T. H.Gan, K. S.Ho, D. Hutchins, and D. Billson
University of Warwick, Coventry, United Kingdom
A pair of non-contact EMATs has been used for thickness measurements and imaging of metallic plates.
This was performed using wide bandwidth EMATs and pulse- compression signal processing techniques,
using chirp excitation. This gives a greatly improved Signal to Noise Ratio (SNR) for air-coupled
experiments, increasing the speed of data acquisition. A numerical simulation of the technique has
confirmed the performance. Experimental results indicate that it is possible to perform non-contact
ultrasonic imaging and thickness gauging in a wide range of metal plates. Advantages over conventional
transient or tone-burst excitation will be discussed.
|