Seafloor Classification Using Multifrequency Interferometric Sonar in Shallow Waters

The objective of this study is to identify specific characteristics of seafloor sediment types to enable automatic classification. Primarily, we focus on the signal amplitude, using the Sonar Equation to analyse backscattered echoes from an off-the-shelf bathymetric sonar system. We employed an Interferometric Sonar, which is also known as Phase Differencing Bathymetric Sonar (PDBS), equipped with multi-frequency transducers. In this paper, we aim to establish the relationship between backscatter levels and incidence angles at two different frequencies: 250 kHz and 450 kHz (with plans to consider 850 kHz in future work). Our approach was to conduct multiple measurements using this sonar system at various frequencies, then compare the results to derive characteristic factors about the amplitude of the signals. These factors will help recognize the behaviour of signals on different sediments, facilitating their differentiation. The insights gained from this study will support the development of more comprehensive methods for future automation of seabed sediment classification. Future developments aim to utilize existing open-source software for data analysis.