Adaptive Array Signal Processing Employing Sum-and_Difference Technique
| Autor: | Tsui-Tsai Lin, 林垂彩 |
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| Rok vydání: | 1993 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 81 We here present a new adaptive beamforming scheme for signal acquisition with an array consisting of doublets. The scheme is developed based on the amplitude-comparison/sum-and- difference technique employed in conventional monopulse radars. The optimum beamformer is constructed so as to minimize the mean-squared error in the difference-to-sum ratio. With the difference beam used as an auxiliary beam to suppress the desired signal, the resulting sum beam exhibits good interference cancellation capability and insignificant desired signal cancellation effect. Expression of the sum beamformer output signal-to-interference-plus-noise ratio is derived to analyze the effect of beam pointing error under various conditions. To remedy the performance degradation due to a large pointing error, we suggest some modified methods to further improve the robustness of the proposed beamformer. In addition, the closed-form expression for the estimate of the desired source direction is derived, and the corresponding second order analysis is given. We also present an iterative algorithm for preliminary acquisition of the desired source direction. For nonstationary environments, we derive a recursive algorithm for updating the optimum weight vectors and desired source direction given the array snapshot vectors. Numerical results are presented to demonstrate the efficacy of the proposed method. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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