Angular Dependence of ${\cal K}$ -Distributed Sonar Data

Abstract

Backscattered signal statistics are widely used for target detection and seafloor characterization. The K-distribution shows interesting properties for describing experimental backscattered intensity statistics. In addition to the fact that its probability distribution function accurately fits actual sonar data, it advantageously provides a physical interpretation linked to the backscattering phenomenon. Sonar systems usually record backscattered signals from a wide angular range across the ship's track. In this context, previous studies have shown that backscatter statistics strongly depend on the incidence angle. In this paper, we propose an extension of previous works to model the angular evolution of the K-distribution shape parameter. This evolution is made clear and analyzed from experimental data recorded with two sonar systems: a 95-kHz multibeam echosounder and a 110-kHz sidescan sonar. Model fitting with data backscattered from six seafloor configurations shows the improvement provided by our extension as compared to two previous models.

Recommendations for improved and coherent acquisition and processing of backscatter data from seafloor-mapping sonars

“…The angular dependence is a fundamental characteristic of the backscatter response (Le Chenadec et al 2007;Clarke et al 1997), which imply specific operations in the data processing (Augustin and Lurton 2005;de Moustier 1986;Hellequin et al 2003;Gravilov 2011;Schimel et al 2015) and complexity in their interpretation (Hasan et al 2012;Dugelay et al 1996;Fonseca and Mayer 2007;Huang et al 2013;Lamarche et al 2011;Rzhanov et al 2012). A rough and hard seafloor interface, usually from coarse material or rocks results in isotropic scattering of the sound waves so that the average Fig.…”

Modern morpho-sedimentological patterns in a tide-dominated estuary system: the Bay of Brest (west Britanny, France)

“…The side-scan sonar signatures result from backscatter variation (imagery) that depends on the seabed material and its macro-morphology (Augustin & Lurton, 2005;Augustin et al, 1996;Lamarche, Lurton, Verdier, & Augustin, 2011;Le Chenadec, Boucher, & Lurton, 2007;Lurton, 2003). Their identification relies on the interpretation of shades of grey and apparent textures in the mosaic.…”

Megabenthic assemblage structure on three New Zealand seamounts: implications for seafloor massive sulfide mining

“…Backscatter data derived from multibeam were processed using SonarScope (Augustin & Lurton 2005). Processing consisted of statistical compensation of the signal as a function of its incidence angle on the seafloor, to attenuate the strong signal from specular reflection at the nadir and the rapid decrease of the signal strength with increasing incidence angle (Hughes Clarke et al 1997, Le Chenadec et al 2007, Fonseca et al 2009). Magnetivity data were collected at 500 m resolution over all 3 seamounts during TAN1007 using a Sea Spy Magnetics overhauser …”