Analysis of sedimentary bottom impulse response using a wide band sonar

This work deals with the estimation of bottom acoustic attenuation coefficient. During natural environment experiments, lake bottom echoes have been collected by using a wideband chirp sonar. The authors estimate at first the bottom experimental impulse response which contains the bottom reflection characteristics over the whole frequency range of the emitted signal. The impulse response is analysed by time-frequency representation in order to estimate the attenuation coefficient which can be used as an important parameter for bottom classification. For estimating the attenuation coefficient, two types of bottom are considered: layered bottom and continuous acoustic impedance variation bottom. The obtained estimates from the lake bottom echoes compared to what can be deduced of the geophysical properties of the sediment