Browsing by Subject "Direction finding"
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Item Open Access Mode separation and direction of arrival estimation in HF links(Wiley-Blackwell Publishing, 2003) Arikan, F.; Yilmaz, N.; Arıkan, Orhan; Miled, M. K. B. H.Estimation of arrival angles and incoming signals is a challenging problem for HF channels where the signals are correlated and the separation between the signals can be as low as a couple of degrees. In this paper, a new algorithm, Multipath Separation- Direction of Arrival (MS-DOA), is developed to estimate both the arrival angles in elevation and azimuth and the incoming signals at the output of the reference antenna with very high accuracy. The MS-DOA algorithm provides reliable angle and signal estimates even with small separation of arrival angles and for low SNRs. The minimum number of antennas that are required by the algorithm is only one more than the number of incoming signals. In a narrowed down region of interest and for a few incoming signals, the computational search time for MS-DOA is only a couple of minutes in a Standard PC.Item Open Access Sparsity based off-grid blind sensor calibration(Elsevier, 2019) Çamlıca, S.; Yetik, I. S.; Arıkan, OrhanCompressive Sensing (CS) based techniques generally discretize the signal space and assume that the signal has a sparse support restricted on the discretized grid points. This restriction of representing the signal on a discretized grid results in the off-grid problem which causes performance degradation in the reconstruction of signals. Sensor calibration is another issue which can cause performance degradation if not properly addressed. Calibration aims to reduce the disruptive effects of the phase and the gain biases. In this paper, a CS based blind calibration technique is proposed for the reconstruction of multiple off-grid signals. The proposed technique is capable of estimating the off-grid signals and correcting the gain and the phase biases due to insufficient calibration simultaneously. It is applied to off-grid frequency estimation and direction finding applications using blind calibration. Extensive simulation analyses are performed for both applications. Results show that the proposed technique has superior reconstruction performance.