Multistatic Sonar Imaging: Comparisons Between the Matched Filtering Method and a Reconstruction Method Based on the Kirchhoff Approximation

摘要

In this study, comparisons are made between two imaging techniques in the context of the Multistatic Synthetic Aperture Sonar (SAS): the Matched Filtering method and a reconstruction method based on the Kirchhoff Approximation (KA). The Matched Filtering Algorithm (MFA) is the classical method used for image formation purposes in synthetic aperture systems. In this method the field diffracted by the target is approached by the "point scatterers" model. One of the first objective of this work is to develop a more complex and more realistic model than the well known "point scatterers" model. In addition, the aim is to get not only the shape and the size of target but also some quantitative information about its physical properties. Thus, a forward model based on the KA is proposed to get a more realistic description of the scattered field and a reconstruction method has been obtained through the use of a 2-D Fourier transform of this forward model. The algorithm hence obtained is named: "Imaging Reconstruction Algorithm in the Kirchhoff Approximation" (IRAKA). In this paper the IRAKA is compared to the MFA in order to check its capability to reconstruct target shape. Images of 2-D targets of circular and elliptic cross-sections are reconstructed with the MFA and with the IRAKA from both numerical data and tank experimental data. These imaging methods are compared in terms of quality of the shape reconstruction and in terms of their robustness to noise in a given multistatic configuration. Both algorithms are also used to reconstruct images of a 2-D target of circular cross-section in a multistatic forward looking SAS context. With a good Signal to Noise Ratio (SNR) we get better results with the IRAKA than with the MFA in terms of the quality of target shape reconstruction. In presence of additive white Gaussian circular noise, the MFA off course, gives better results than the IRAKA. Nevertheless, using a technique of stabilization of the deconvolution, it has been possible to improve the performances of the IRAKA even in presence of additive noise.