Search

Non-cooperative moving targets typically appear defocused in synthetic aperture radar (SAR) images as they are non-stationary during the coherent processing interval. Typically, the problem of refocusing moving targets in SAR scenes is addressed as a problem of the target's motion estimation and compensation. In this study, the problem is addressed as a problem of non-cooperative target imaging and the authors propose a solution based on the use of inverse synthetic aperture radar (ISAR) processing to solve this problem. Taking into consideration the advantages of SAR processing, the problem is tackled starting from formed SAR images, where non-cooperative targets images are firstly detected, then backprojected to the received data domain and reprocessed as ISAR data. The effectiveness of the proposed method is then tested on Cosmo-Skymed spotlight SAR data of maritime targets. [ABSTRACT FROM AUTHOR]

A number of significant airplane accidents have resulted from windshear encounters during takeoff or landing. In these situations the radar signal received may be affected by a strong ground clutter that may make the conventional windshear detection algorithms implemented on ground-based systems unusable. Typically, the solution to this problem is to employ a clutter rejection filter and then process the filter output to derive weather information. In this study, a parametric bimodal spectral model of the raw radar signal from an airborne Doppler weather radar is proposed. The bimodal shape of the model has been defined as a superposition of clutter and windshear. The model can be used to define a windshear detection algorithm that can also directly estimate the physical weather parameters by using the estimated model parameters without using a clutter rejection pre-filter. Owing to the impossibility of testing a windshear detection system in a realistic environment, a simulated windshear data base has been developed by National Aeronautics and Space Administration (NASA) and Federal Aviation Administration (FAA) during their windshear research programme. The purpose of this study is to define a parametric bimodal spectral model and demonstrate its validity on the NASA-FAA windshear certification data set. [ABSTRACT FROM AUTHOR]

A technique is proposed for reconstructing wide range profiles using stepped-frequency waveforms (SWFs). The technique is based on reconstructing range sub-profiles. With respect to previous methods, the proposed technique can be applied to any kind of SWFs. Moreover, for a given range resolution, long range profiles can be formed without increasing the number of transmitted frequencies. Theoretical results are also derived that provide a correct setting of waveform and processing parameter. Finally, as case studies, the proposed method is applied to three SFWs, namely short-pulse stepped-frequency, linear frequency modulated stepped frequency and phase-coded stepped-frequency waveforms. Simulations prove the effectiveness of the proposed range profile reconstruction. [ABSTRACT FROM AUTHOR]