Sidescan Sonar

Sidescan sonar allows obtaining an acoustic image of the seafloor at high resolution, wide swath and relatively low cost. For that purpose the backscattered signal of an acoustic pulse sent out sideways from an instrument carrier is registered. At low incident angles small-scale relief is well imaged and the length of shadows allows calculation of the height of seafloor features but sidescan sonar is particularly useful in mapping compositional differences of the seafloor. Sidescan sonar images are, however, mostly uncalibrated and need some form of ground-truthing for meaningful geological interpretation. Interferometric sidescan sonar systems now also provide bathymetric information together with backscatter strength