Bottom classification using information in the spectral domain and time-frequency domain

This work deals with the response of underwater bottom insonified with wideband ultrasonic signals. The aim of the study is to investigate the feasibility to recognize the nature of sediment layer using a wideband sonar system. The processing of signals must take into account the wide frequency band of the backscattered echoes and so includes spectral analysis and time-frequency analysis. The experiments have been performed in a natural environment, in Lake Geneva. Bottom echoes have been collected on 5 different types of bottom. For each backscattered echo signal, 3 vectors of features have been extracted: directly from the amplitude of the impulse response spectrum or from the parametric modeling or from the time-frequency representation. The results of the classification by using a neural network are then analysed