The ultrasonic pulse-echo technique, widely used in nondestructive testing and medicine, uses a part of the echo content, yielding only a qualitative image. In order to extract quantitative information from echographic signals, characterization techniques have been developed. Most of them are based on the power-spectrum estimation of received signals. However, in most cases data processing is time consuming and prevents real-time display of the data. In order to shorten this time the authors assembled a Fourier transformer which processes a 1024-point Fourier transform in 2 ms. The whole data-processing system can be connected to any commercial acoustic-imaging system, if necessary through a radio-frequency signal digitalizer.