A pulse-length correction to improve energy-based seabed classification in coastal areas

Vertical Configuration of a Side Scan Sonar for the Monitoring of Posidonia oceanica Meadows

“…Regarding the bottom detection, the available literature shows several methods. For example, it has been assumed that the beginning of the seabed that is acoustically detected is one pulse length before the range where the maximum intensity of the echo is reached [48] or the range where the echo exceeds a particular threshold before the range of the maximum intensity [49] and, in the case of seabed covered with vegetation, the bottom has been identified where the echo reaches the maximum backscatter [19] or by applying a threshold with respect to the maximum value of the echo [34]. The methodology applied here, a small threshold relative to the maximum limit, considers the range of the maximum value of the echo without reaching the defined maximum limit and it is between the first two and the last methodologies named above [34,48,49].…”

What can a low-cost fish-finder tell us about the seabed?

“…Because of the spherical symmetry of the sound wave emitted by the transducer and the attenuation through the water column, the echo intensity depends on the distance travelled and must be corrected to remove depth effects (Biffard et al, 2005(Biffard et al, , 2010Caughey & Kirlin, 1996;Pouliquen, 2004;Rodríguez-Pérez et al, 2014) (see Fig. 3).…”

Extraction of visual texture features of seabed sediments using an SVDD approach

“…In previous studies, most seabed surveys were conducted by utilizing acoustic techniques based on sonar systems such as single beam, side-scan, multi-beam and acoustic ground discrimination systems (AGDS) (Collier and Brown, 2005;Ji et al, 2013;Ji and Liu, 2015). In addition, physically motivated echo features were proposed to identify seabed types (Rodríguez-Pérez et al, 2014). Orlowski et al introduced two energies they termed the roughness index and hardness index as features to classify the type of seabed (Orlowski, 1984).…”