Low elevation target detection and direction finding

Uyar, Görkem
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).


Parametric estimation of clutter autocorrelation matrix for ground moving target indication
Kalender, Emre; Tanık, Yalçın; Department of Electrical and Electronics Engineering (2013)
In airborne radar systems with Ground Moving Target Indication (GMTI) mode, it is desired to detect the presence of targets in the interference consisting of noise, ground clutter, and jamming signals. These interference components usually mask the target return signal, such that the detection requires suppression of the interference signals. Space-time adaptive processing is a widely used interference suppression technique which uses temporal and spatial information to eliminate the effects of clutter and ...
Low velocity moving target detection with synthetic aperture radar
Narin, Görkem; Koç, Seyit Sencer; Department of Electrical and Electronics Engineering (2019)
Detection of slow moving targets with small radar cross sections (RCS) is a challenging problem for the Ground Moving Target Indication (GMTI) systems. GMTI systems face high false alarm and/or frequent target miss rates for such targets. Synthetic Aperture Radar (SAR) systems, on the other hand, offer sufficiently large target energy return, unfortunately not localized to a point in the SAR image due to target motion. This thesis is focused on the study of two methods for moving target detection in SAR ima...
Slow moving target detection for airborne radar systems by dynamic programming on SAR images
Gurer, Gorkem; Koc, Sencer; Candan, Çağatay; Orguner, Umut (2019-04-01)
A dynamic programming based approach is proposed to detect slow moving, low reflectivity targets for airborne radar systems. The suggested method utilizes the reflectivity amplitudes of the SAR image, possibly containing multiple slow moving targets, and poses the target detection problem as a maximum likelihood sequence detection problem. Dynamic programming is applied to capture the target related features such as along track smeared target signatures in the SAR image to this aim. Typical clutter and targ...
A Knowledge based approach in GMTI for the estimation of the clutter covariance matrix in space time adaptive processing
Anadol, Erman; Tanık, Yalçın; Department of Electrical and Electronics Engineering (2012)
Ground Moving Target Indication (GMTI) operation relies on clutter suppression techniques for the detection of slow moving ground targets in the presence of strong radar returns from the ground. Space Time Adaptive Processing (STAP) techniques provide a means to achieve this goal by adaptively forming the clutter suppression filter, whose parameters are obtained using an estimated covariance matrix of the clutter data. Therefore, the performance of the GMTI operation is directly a ected by the performance o...
Jammer cancelation by using space-time adaptive processing
Uysal, Halil; Severcan, Mete; Department of Electrical and Electronics Engineering (2011)
Space-Time Adaptive Processing (STAP) has been widely used in spaceborne and airborne radar platforms in order to track ground moving targets. Jammer is an hostile electronic countermeasure that is being used to degrade radar detection and tracking performance. STAP adapts radar’s antenna radiating pattern in order to reduce jamming effectiveness. Jamming power that enters the system is decreased with respect to the adapted radiation pattern. In this thesis, a generic STAP radar model is developed and imple...
Citation Formats
G. Uyar, “Low elevation target detection and direction finding,” M.S. - Master of Science, Middle East Technical University, 2012.