Low elevation target detection and direction finding

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Elektrik ve Elektronik Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2012

Öğrenci: GÖRKEM UYAR

Eş Danışman: MUSTAFA KUZUOĞLU, YALÇIN TANIK

Özet:

Ground based radars often experience difficulties in target detection and direction finding (DF) applications due to the interference between the direct and surface reflected signals when the targets fly at low altitudes. In this thesis, the phenomena governing the low angle propagation are overviewed and a multipath signal model including the effects of refraction, specular reflection, diffuse reflection, curvature of the earth and antenna polarization is presented. Then, the model is utilized to develop detection and DF algorithms for the targets at low altitudes. The target detection algorithm aims to increase signal-to-noise ratio (SNR) to overcome the effects of signal fading caused by surface reflections. The algorithm is based on diversity combining and the combining weight vector is calculated by maximizing average value of SNR. The technique is compared with Maximum Ratio Combining (MRC) algorithm which is optimal in terms of SNR. In direction finding, it is the height of the target that is explored since the target range information is obtained from the time delay. The target height is estimated by utilizing Maximum Likelihood Estimation (MLE). The performance of our algorithm is compared with that of the technique that is known in the literature as Refined Maximum Likelihood (RML).