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Item L0 NORM OPTIMIZATION IN SAR IMAGE RECONSTRUCTION BASED ON SPARSE DECOMPOSITION(Бургаски свободен университет, 2015) Лазаров, Андон; Минчев, ДимитърSynthetic Aperture Radar SAR) image reconstruction algorithms based sparse decomposition is considered. The linear frequency modulated (LFM) signal reflected from the scene, relief of the Earth surface is presented as matrix multiplication of three matrices: azimuth Inverse Discrete Fourier Transform (IDFT) matrix, image matrix and range IDFT matrix. L0 norm optimization image reconstruction procedure is applied over reduced number of measurements defined by randomly generated azimuth and range sensing matrix. The geometry of the scene is described by standard Matlab „peaks” function. Results of numerical experiments are provided.Item Digital elevation models of territories under risk in Caucasus region-Armenia(Бургаски свободен университет, 2011) M.A. Grigoryan; G.M. Aleksanyan; T.N. Boyakhchyan; G. Kh. Navasardyan; L.A. Gevorgyan; Лазаров, Андон; Минчев, ДимитърIn this paper results of international team from BFU and YSU in the frames of NATO Project NATO CLG: ESP.EAP.CLG. 983876) are described. Digital Elevation Model (DEM) for selected areas of Armenia with high level of risk where natural disasters such as grounds sedimentation, landslides, mudflows, earthquakes are periodically happen, is generated. DEM can be used to create regional system for monitoring natural disasters (to control topographic changes on the territories with high level of risk) on the territory of Armenia. Tools such as InSAR systems, systems of mathematical models, GIS technologies and mathematical algorithm for processing satellite images are used. The results of monitoring and modeling can be periodically introduced to local authorities to take measures in order to prevent probable natural disasters impact on population and communications.Item SAR pseudo differencial interferogram modeling(Бургаски свободен университет, 2011) Лазаров, Андон; Минчев, ДимитърThis work addresses an algorithm of Synthetic Aperture Radar (SAR) interferogram modeling to evaluate surface displacement. The interferogram obtained is called pseudo differential interferogram. Measurements of two SAR satellites placed in one and the same point of observation are used. Linear frequency modulated emitted signal is used to produce reflected by the surface SAR signal. Two-dimensional Fourier transform is applied to extract two single look complex (SLC) images. Pseudo differential interferogram showing the ground displacement is computed. To verify proposed model a numerical experiment realization implemented in MATLAB® environment is presented.Item BISAR algorithms and MATLAB implementation(Бургаски свободен университет, 2011) Лазаров, Андон; Костадинов, ТодорThis paper deals with program implementation of Bistatic Inverse Synthetic Aperture Radar (BISAR) using to extract a high resolution image of a moving target. BISAR is a bistatic topology with stationary transmitter and receiver and a moving target. The transmitter, receiver and target, represented as an assembly of point scatterers are situated in separate coordinate systems. Geometrical and kinematical equations and a mathematical model of deterministic LFM BISAR signal are described. A program code of signal formation and image extraction is implemented in MATLAB.Item ISAR signal formation and image extraction as direct and inverse projective operation(Бургаски свободен университет, 2011) Лазаров, АндонIn this work ISAR (Inverse Synthetic Aperture Radar) signal formation and image reconstruction are analytically described and interpreted as direct and inverse projection operation. LFM (Liner Frequency Modulated) and PCM (Phase Code Modulated) emitted waveforms are used while modeling reflected ISAR returns. Complex projection operator and its Taylor expansion in the signal formation and image reconstruction procedures are defined.Item SAR модел на процеса на изобразяване(Бургаски свободен университет, 2010) Лазаров, Андон; Минчев, ДимитърThis work addresses the model of SAR imaging process. SAR Geometry with thoroughly mathematical description of the observed surface is suggested. SAR emitted signal with linear frequency modulation is used to produce reflected by surface SAR signal model presented as four-dimensional array (matrix) and generated by Hadamard product with special defined rectangular function. Two-dimensional Fourier transform is applied to obtain single look complex image, which can be used to generate interferograms. To verify proposed geometrical and signal models a realization of the processing chain, implemented in MATLAB environment is illustrated.Item ISAR image reconstruction algorithm(Бургаски свободен университет, 2010) Лазаров, АндонThis paper deals with generalized ISAR geometry and image reconstruction technique. Three-dimensional (3-D) ISAR scenario is projected on two-dimensional (2-D) radar registration plane. The arbitrary movement of the object is decomposed into two components: radial displacement of the object’s geometric center and rotational movement around it. It is proven that the demodulated ISAR signal, reflected from the target during aperture synthesis, can be considered as 2-D Fourier transformation of the image function, corrected by an exponential term and as a consequence, the image function can be extracted by 2-D inverse Fourier transformation of the phase corrected ISAR signal. Numerical experiment validating aforementioned statements is performed.Item InSAR геометрия и базови операции(Бургаски свободен университет, 2010) Лазаров, АндонIn the present work based on geometrical interpretation of Inverse Synthetic Aperture Radar (InSAR) scenario, main parameters, characteristics and operations over InSAR data are defined. SAR interferogram and interferometric phase SAR equations are derived and procedure of interferogram flattening is given. The procedures of terrain motion evaluation and differential interferogram generation are presented. Basic operations including rectification of the elevation map, co-registration, and coherence evaluation, and phase unwrapping are discussed. Numerical experiment is carried out to verify geometrical interpretation of the interferogam generation and main operation performance.