Observation of V(z) curves with multiple echoes

Abstract Until now the acoustic material signature technique (AMS) has largely been described and used in the high frequency area (100 MHz to 2 GHz). Today more and more industries are interested in method. However, many observed samples show structures calling for the use of low frequencies (a few MHz). In the classical AMS method, where only the first reflected echo (one round trip in the water coupling medium) is considered, the contrast of the V ( z ) curves is sometimes very poor. In this paper an original method is reported that uses the information carried by the second reflected echo and makes it possible in various circumstances to significantly increase the contrast in the V ( z ) curves.