Terrain profile estimation over a synthetic terrain by using pulse-doppler radar
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The systems used for terrain profile estimation arise when the safety flight issues in civil flight transport and in military applications become important. These systems are developed for the purpose of terrain avoidance and safe flight. In this thesis, we study two techniques in estimating the terrain profile of the synthetically generated terrain which is achieved by means of signal processing. The estimation performance of the techniques is observed according to the results of flight simulations realized on the simulation environment. In the simulations, an aircraft with a pulse-Doppler radar scans a synthetic terrain according to the scanning patterns to generate the received signals. The techniques that we propose, are applied to the output of the pulse-Doppler process. The first technique is based on the usage of the first and the middle reflection range points in the clutter received signal. An adaptive thresholding method is developed for robust detection of these points. Accurate detection of these range points is crucial in the estimation performance of the first approach. The other technique uses the relation between the elevation angle θ and the clutter received signal amplitude ratio of the two receiver antennas R1 and R2 in finding the θ angles of the reflections in corresponding range values. In this approach, accurate estimation of the angle of arrival is important on the performance of estimation. Especially for far ranges, the errors in the estimation become more sensitive to the errors in the elevation angle θ. Finally, over a set of synthetically generated terrain profiles, the error performance of these two techniques are investigated and compared.