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Radar Target Parameter Estimation Using Frequency and Space Diversity

Sebt, Mohammad Ali | 2011

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 41892 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Nayebi, Mohammad Mahdi
  7. Abstract:
  8. In this dissertation, the application of frequency and space diversities in radar target parameter estimation are investigated. On this basis, multi-frequency signal is used to improve the range resolution, array structure is used to increase the angle estimation accuracy and the merger of the multi-frequency signal and array structure are used to increase the maximum number of targets that can be uniquely identified.Considering the desirable properties of multi-frequency signals such as high bandwidth efficiency, high range resolution achievement without chip length decrease and …, there has been increased interest in the vast area of research on the design of such signals that has continued up to the present time. However, a method that achieves a signal with low sidelobe level in the ambiguity function and peak to average power ratio near one is not presented yet. In this thesis, an optimum method for multi-frequency signal design is presented that its resultant signal has both low sidelobe level in the ambiguity function and peak to average power ratio near one.Here, as is usual, the use of space diversity is proposed to estimate the angle of targets and the aim is to find a method by which low altitude targets can be tracked well. First, it is explained that how the presence of the earth can lead to major errors while estimating the angle of low altitude targets. Then, to overcome this problem, a new array beamforming to shape the sum and difference patterns in mono-pulse technique is presented by which the angle of low altitude targets can be estimated with the accuracy better than the one tenth of the beamwidth. Considering the high accuracy of angle estimation and the light load of computations, the proposed method is noteworthy in comparison with other methods.At last, in view of the mentioned benefits of the frequency and space diversities separately, the idea of using both of them to improve the parameter identifiability is presented in this dissertation. It is shown how the use of multi-frequency signal can increase the maximum number of targets that can be uniquely identified by an array radar. This property is a motivation to investigate the multi-frequency array radar more seriously than what is presented in the literature. So, the signal model, ML estimator, ML cost function optimization algorithms and the Cramer-Rao lower bound are derived for the the proposed multi-frequency array radar
  9. Keywords:
  10. Multi-Frequency Signal ; Array Receiver ; Multifrequency Array Radar

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