On-line Sea Beam Acoustic Imaging

This paper describes a system designed and built at the Marine Physical Laboratory of the Scripps Institution of Oceanography to produce acoustic images of the seafloor on-line with a Sea Beam multibeam echo-sounder. This system uses a stand alone interface between the Sea Beam system and a grey-scale line-scan recorder. The interface is built around a Motorola 68000 microprocessor and has digitizing capabilities. It digitizes the detected echo signals from each of the 16 preformed beams inside the Sea Beam echo processor as well as the roll information given by the ship´s vertical reference. The acoustic data are then roll compensated and combined into a port and a starboard time series. These time series are eventually output in digital format to a line-scan recorder which produces the grey scale acoustic image. Results are discussed for Sea Beam acoustic images of the seafloor and of the Deep Scattering layers.