Detection and classification of buried targets and sub-bottom geoacoustic inversion with an AUV carried low frequency acoustic source and a towed array

An innovative bottom acoustic survey technique involving an Autonomous Underwater Vehicle (AUV) is presented. In this technique, the AUV carries a low frequency broadband acoustic source and a towed acoustic array and operates close to the seabed. The proposed technique has great potential to improve the capability of detecting and classifying buried or half buried targets, and providing a more reliable sub-bottom geoacoustic inversion method over a large area for geological and geophysical surveys. Specifically, since the source and the receiving array are very close to the seafloor, a variety of surface and reflected waves with good SNR is expected to be received by the hydrophone array. All of these waves have their own unique acoustic characteristics, which can be used for seafloor and sub-bottom geoacoustic inversion. Results from numerical simulations based on synthetic data will be presented to demonstrate how the geometric and physical properties of the seafloor, sub-bottom, and buried targets influence the received echoes in either the time domain, the frequency domain, or both. The simulation results will be discussed