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Study On Angle Estimation And Disambiguation Algorithm For Distributed Subarrays Antennas Radar

Posted on:2017-05-20Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y MaFull Text:PDF
GTID:1108330488457292Subject:Signal and Information Processing
Abstract/Summary:PDF Full Text Request
Distributed subarrays antennas (DSAs) radar, as a new radar system, has drawn much attention in radar field since its unique advantages compared with the conventional arrays radar. The DSA radar consists of two or more far separated subarrays radar with small array aperture. In contrast with the conventional array radar, DSA radar can effectively extend array aperture, improve the performance of direction of arrival (DOA) estimation, and enhance the mobility and battlefield viability of the radar system. However, the distance between the subarrays is much longer than half wavelength and does not satisfy the spatial Nyquist sampling theorem, which will result in ambiguities in DOA estimation. Aiming at the preceding problem, this dissertation mainly focuses on the DOA estimation and ambiguity resolution of DSA radar. The main content of this dissertation is summarized as follows:1. The foundation knowledge of DOA estimation for DSA is introduced. Firstly, the signal model of DSA is established, which is the theoretical basis throughout the paper. Then, according to the structural features of DSA, its beam pattern is derived. The beam width and the grating lobe features of DSA are mainly studied on the basis of array beam pattern. The effect of the grating lobe on the performance of DOA estimation is analyzed by simulation experiments. Finally, the dual-resolution estimation of signal parameters via rotational invariance technique (DR-ESPRIT) algorithm is introduced to solve the problem of the angle ambiguities causing by the grating lobe. Moreover, this algorithm is widely applied to the field of DOA estimation for DSA. Simulation results are presented to illustrate better estimation performance of DOA for DSA against conventional array.2. The analytical methods of the performance of DOA estimation for DSA are studied. Firstly, According to the structural features of DSA, its coherent and incoherent Cramer-Rao Bounds(CRBs) are derived. Secondly, the analytical method of the performance of ESPRIT algorithm for uniform linear array is popularized to DSA. Then a method is proposed to analyze the performance of DR-ESPRIT algorithm, and the analytical efficiency is demonstrated by the computer simulation results. Lastly, the basic concepts of the threshold effect are introduced in brief. In order to analyze the threshold effect of DSA, an analytical method of the performance for DSA based on the maximum a posteriori (MAP) estimator is proposed. The proposed method combines the MAP estimator and the above two approaches, respectively. And the signal to noise ratio threshold and baseline threshold of DSA can be approximately calculated by this method. Computer simulation results show good performance of the proposed method.3. High accuracy DOA estimation algorithms for DSA radar are studied. In order to reduce the effect of SNR threshold and baseline threshold on the performance of DOA estimation, several high accuracy DOA estimation algorithms for DSA on the basis of DR-ESPRIT algorithm are proposed. Firstly, from point of view of optimizing the subarray elements, a high accuracy DOA estimation algorithm for DSA based on optimal subarray partition is proposed. The proposed algorithm improves the accuracy of the reference estimation by utilizing optimal subarray partition. It will reduce the effect of SNR threshold on the performance of DOA estimation for DSA. Then, from point of view of restructuring the configuration of DSA, a high accuracy DOA estimation algorithm for DSA based on the auxiliary subarray is proposed. The proposed algorithm applies an auxiliary subarray between the subarrays of the original array to obtain a new DSA. The high accuracy and unambiguous DOA estimation is obtained by the combination of the rotational invariance between the subarrays of the new array and the multi-step disambiguation method. Finally, a high accuracy DOA estimation algorithm for the Multi-baseline DSA is proposed. The high accuracy and unambiguous DOA estimation can be obtained by utilizing the proposed algorithm when the number of sensors of distributed subarrays is limited by the area of platform. Moreover, the performance of DOA estimation of the proposed algorithms is analyzed via the MAP estimator. Furthermore, approximate methods for SNR threshold and baseline threshold calculations are presented. Computer simulation results are given to verify the effectiveness of the proposed algorithms.4. High accuracy angle estimation algorithms for bistatic MIMO radar with DSA are studied. Considering the advantages of DOA estimation using bistatic MIMO radar, the DSA is applied to bistatic MIMO radar and the related DOA estimation algorithms are proposed. Firstly, an angle disambiguation method for bistatic MIMO radar with sparse array by using the range information of targets is proposed. The proposed method innovativly uses the range information of targets and the geometry of bistatic MIMO radar to disambiguate the angle ambiguity. Then high accuracy and unambiguous DOA and direction of departure (DOD) estimations are obtained. After that, the improved DR-ESPRIT algorithm is proposed according to the disambiguation method mentioned above and the principle of automatically paired ESPRIT algorithm. An automatically paired DR-ESPRIT based on the angle disambiguation method by using the range information of targets is proposed. Furthermore, the performance of the proposed algorithm is analyzed according to its statistic characteristics of estimation error. An approximate method for calculating the baseline threshold is also presented. The proposed algorithm relaxes the restriction on the aperture of transmitting array, and the accuracy of angle estimation is improved. Moreover, the DOD and DOA estimation using the proposed method is automatically paired. Simulation results show the good performance of the proposed method and the effectiveness of the performance analysis method.
Keywords/Search Tags:Distributed Subarrays Antenna(DSA)radar, Direction Of Arrival(DOA) estimation, Cramer-Rao Bound(CRB), ambiguity resolution, threshold efiect, Maximum A Posteriori(MAP)
PDF Full Text Request
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