Underwater multi-frequency transmitter for seabed characterization

In the underwater acoustic domain, there is a large interest for techniques able to achieve seafloor characterization. This study is to take advantage of the saturation effect to generate simultaneously several frequencies with a single source: generated harmonic components of a shock wave become the exploited acoustic beams. The source is unique in time and space so that the multi-frequency responses are inherently perfectly matched. Such a system could offer frequency diversities useful for applications such as detection of sunken oil slicks or sediment characterization. The goal is the study of feasibility of such a source. In a preliminary approach, a pseudo-1D model is used to estimate the on-axis levels of the first multiple frequencies. Three antennas have been tested and experimental results are presented.