Expendable Acoustic Source for AUV Based Geoacoustic and Geotechnical Survey Operations

Our team proposes a unique expendable acoustic source comprised of flexural disc technology in a close packed arrangement that allows for a reduction in resonant frequency and an increase in useful bandwidth. This array will be designed to couple as much energy as possible into the bottom sediments, while coupling as little energy as possible directly into the surrounding water column. This is a difficult task for an unspecified and potentially unknown bottom type, but an array of flexural discs designed to sit on the sea floor will make it possible to achieve this goal in many cases. Our source will generate continuous M-sequence waveforms which are excellent for geoacoustic inversion. M-sequence waveforms will be used to provide significant information on the structure of bottom sediments by simultaneously providing very high resolution in both time delay of arrival and Doppler space, limited only by the coherence of the medium. M-sequence waveforms exhibit a white spectrum and, after the specified detection processing, will provide the desired thumbtack ambiguity function, i.e., high resolution in both time of arrival and Doppler space.