OPEN ACCESS
In this article, and to contribute to the study of the problem of maritime surveillance, we propose to characterize sea clutter using a statistical approach. In general, the statistical study of sea clutter requires to have significant material installed in a maritime environment, this to acquire a database of real signals broadcast by a sea surface. Therefore, in this paper, we choose to generate the sea surface by using the Elfouhaily sea spectrum. On the other hand, the Physical Optics approximation is used to calculate the diffusion coefficient of a sea surface. In this sense, a database of scattering coefficients is well established (for the fixed electromagnetic characteristics of the sea water), by varying the observation geometry, the polarization of the wave (at the emitter and at the receiver), the wind speed and wind direction. To analyze the distribution of electromagnetic scattering coefficients, we propose to use for the first time, the -ߙstable distribution, we compare the results obtained with those given by the two commonly used in statistical distributions: the Weibull and ࣥlaw. The Kolmogorov-Smirnov evidence is used to show that the -ߙstable model is best suited to our database. Therefore, we look more specifically the influence of the polarization, the wind speed and wind direction on the parameters of -ߙstable distributions. The parameter ߜparticular position allows to discriminate the probability density of the parameter ߜfor some configurations.
RÉSUMÉ
Dans cet article, en vue d’une problématique de surveillance maritime, nous proposons de caractériser le fouillis de mer en utilisant une approche statistique. En général, l’étude statistique du fouillis de mer nécessite d’avoir des moyens matériels importants, installés dans un environnement maritime, permettant d’acquérir une base de signaux réels diffusés par une surface maritime. Par conséquent, dans ce papier, nous choisissons d’une part, de générer une surface maritime à partir du spectre d’Elfouhaily. D’autre part, l’optique physique est utilisée pour calculer le coefficient de diffusion d’une surface maritime. Dans ce sens, une base de données de coefficient de diffusion est ainsi constituée, pour des caractéristiques électromagnétiques de l’eau de mer fixées, en faisant varier la géométrie d’observation, la polarisation de l’onde (à l’émission et à la réception), la vitesse du vent et la direction du vent. Pour analyser la distribution des coefficients de diffusion électromagnétique, nous proposons l’utilisation pour la première fois, de la loi -ߙstable que nous comparons aux résultats obtenus avec les distributions statistiques généralement utilisées : la loi de Weibull et la loi .ࣥLe test de Kolmogorov-Smirnov permet d’affirmer que le modèle alpha-stable est le plus adapté à notre base de données. Par conséquent, nous regardons plus particulièrement l’influence de la polarisation, de la vitesse du vent et de la direction du vent sur les paramètres des distributions -ߙstables. Le paramètre de position delta permet notamment de discriminer les densités de probabilité du paramètre ߜpour certaines configurations.
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