Acoustic images of objects moving under an inhomogeneous layer

Acoustical Imaging in Heterogeneous Environments

“…Later developing this idea, he proposed a method of beamforming of flexible towed array which shape could randomly vary, but measuring of the shape was not necessary. Another methods of acoustical imaging in heterogeneous and scattering medium, based on the methods of nonlinear phase speckle interferometry has been proposed and developed in [37][38][39][40][41][42][43], where it was shown that it is possible to uniquely recover the trajectory of a sound source moving in a ocean waveguide or in strongly scattering medium, and with an accuracy of the diffraction resolution of the array. In [41], this approach was applied for visualization of fluid flow through inhomogeneous layers, and in [42] the ability of acoustical imaging of extended objects, located at the inhomogeneous scattering medium was demonstrated.…”

“…The same ideology of speckle processing can be applied to the detection of the moving point sources in ocean waveguides. It is shown in [39,40,43] that in some conditions multi ray structure of acoustic field in a waveguide with vertical stratification of sound speed can be considered as speckle structure and speckle interferometry methods can be used for the detection of moving sound source in ocean channel and measuring its trajectory. It is known that rather long horizontal array can resolve vertical rays especially under big inclination angles.…”