A technique for estimation of surface roughness [of underwater structures and seabottom]

A wideband technique for acoustic remote sensing of the roughness and slope of the surfaces of underwater natural and manmade structures and of the seabottom is outlined. The technique jointly processes two or more wideband echoes obtained simultaneously from slightly different directions of view and from the same insonified resolution cell. A comparison in the frequency domain between the echoes, which are less correlated when the surface roughness increases, provides an estimation of surface roughness and slope. Laboratory experiments give encouraging results on the capability of this technique to estimate surface roughness, even for roughness values larger than the transmitted wavelength. A range of roughness of many decades can be covered, with a standard deviation of the estimation error on the order of 0.3 times the true value