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Communication dans un congrès

Low Frequency Synthetic Aperture Sonar: Spatial Coherence Analyse

Fabien Novella 1 Yan Pailhas Gilles Le Chenadec 1 Isabelle Quidu 1
1 Lab-STICC_ENSTAB_CID_PRASYS
Lab-STICC - Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance
Abstract : Spatial coherence is a widely studied notion for HF SAS. It allows the estimation of the navigation of the platform with an accuracy well below the wavelength of the system . It also allows, for high-frequency SAS images, the detection of stable reflectors generally symptomatic of manufactured objects. The theoretical background of spatial coherence is based on a derivation of the Van Cittert Zernike (VCZ) optics theorem adapted to acoustic. However, this theorem uses some assumptions (narrow band signals, Fresnel approximation, Born approximation and homogeneity of the scattering media) that are not necessary met for low frequency system. In this paper effects of wideband systems and presence of a target in the insonified volume are investigated. Do to so, the study is based on a simulation tool whose results are compared with real data from trials conducted by CMRE with a wideband LFSAS. Thanks to the use of a 2-D array, the two dimensional coherence can be analyzed. A sub-band study enables to respect the narrowband VCZ assumption. A statistical study on distribution of degree of coherence estimates allows to point out the presence of strong scatterers symptomatic of manufactured objects.
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https://hal-ensta-bretagne.archives-ouvertes.fr/hal-03125756
Contributeur : Marie Briec <>
Soumis le : vendredi 29 janvier 2021 - 16:50:48
Dernière modification le : mercredi 14 avril 2021 - 10:40:01

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Fabien Novella, Yan Pailhas, Gilles Le Chenadec, Isabelle Quidu. Low Frequency Synthetic Aperture Sonar: Spatial Coherence Analyse. 179th Meeting of the Acoustical Society of America - Acoustics Virtually Everywhere, Acoustical Society of America, Dec 2020, Virtuel, France. ⟨10.1121/1.5147076⟩. ⟨hal-03125756⟩

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