Phase autofocus is a key step of translational motion compensation (TMC) in inverse synthetic aperture radar (ISAR). In this paper, a modified phase autofocus algorithm is proposed for ISAR to improve the computationa...
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The performance of the conventional Gram-Schmidt orthogonalization of covariance matrix (RGS) beamforming method will decrease significantly when non-ideal factors exists such as the appearances of fast moving interfe...
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ISBN:
(纸本)9781849199940
The performance of the conventional Gram-Schmidt orthogonalization of covariance matrix (RGS) beamforming method will decrease significantly when non-ideal factors exists such as the appearances of fast moving interferences, array platform movement. In order to improve the robustness of interference suppression, a derivative constrained Gram-Schmidt orthogonalization of covariance matrix (CRGS) beamforming method with widened nulls is proposed in this paper. In the proposed method, the number of interference P is initially estimated and the first subspace is reconstructed by Gram-Schmidt orthogonalization of the first P columns of sample covariance matrix. Afterwards, the derivative constrained vectors and the second subspace spanned of these vectors are constructed. At last the adaptive weight vector is obtained by orthogonally projecting the quiescent weight vector onto the interference subspace made up of the first subspace and the second subspace. Based on the numeral simulation results, it is verified that the proposed method can form widened nulls and effectively improve the robustness of interference suppression.
Slow-time MIMO radar is investigated to deal with some cost sensitive applications like UAVs detection to avoid the use of arbitrary waveform generators and digital receivers. But this method suffers from the deterior...
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Orthogonal projection (OP) adaptive beamforming is widely applied in practical scenarios because of strong robustness. However, the performance of traditional OP adaptive beamforming would degrade severely when OP ada...
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ISBN:
(纸本)9781849199940
Orthogonal projection (OP) adaptive beamforming is widely applied in practical scenarios because of strong robustness. However, the performance of traditional OP adaptive beamforming would degrade severely when OP adaptive beamforming is applied at subarray level, especially in asymmetrical subarray configuration. To overcome this problem, the improved orthogonal projection (IOP) adaptive beamforming based on normalization at subarray level is proposed. In the proposed method, the covariance matrix is firstly modified by normalizing the noise power at subarray level. Subsequently, the interference subspace is estimated by eigenvalue decomposition, and then the adaptive weight is calculated by using OP adaptive beamforming. Numeral simulation results show that the proposed method at subarray level outperforms the traditional OP adaptive beamforming and the output signal-to-interference-plus-noise ratio (SINR) is close to the optimum value. The proposed method can be significantly effective in practical applications.
This paper proposed a genetic algorithm based on division position coding to solve the optimization of subarray partition in monopulse application, which aims at finding the best compromise between sum and difference ...
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ISBN:
(纸本)9781849199940
This paper proposed a genetic algorithm based on division position coding to solve the optimization of subarray partition in monopulse application, which aims at finding the best compromise between sum and difference patterns. In the proposed method, the division position is encoded as a chromosome gene, then the initial population is randomly generated by a series of non-repeated integers, and the fitness calculation and genetic operation are subtly designed to improve the convergence and stability. Various numeral simulation results are presented to verify the effectiveness of the proposed method.
Beam pattern synthesis is of great interest for colocated MIMO radar with larger aperture. Sever gating lobes and high sidelobe level would cause great performance loss when the transmitting array is sparse. In order ...
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Conventional Space-time adaptive processing (STAP) requires large numbers of independent and identically distributed (i.i.d.) training samples to ensure the clutter suppression performance, which is hard to be achieve...
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ISBN:
(纸本)9781849199940
Conventional Space-time adaptive processing (STAP) requires large numbers of independent and identically distributed (i.i.d.) training samples to ensure the clutter suppression performance, which is hard to be achieved in nonhomogeneous environment. In order to obtain improved clutter suppression with small training support, an iterative sparse recovery STAP algorithm is proposed in this paper. In the proposed method, the clutter spectrum sparse recovery and the calibration of space-time overcomplete dictionary are implemented iteratively, modified focal underdetermined system solution (FOCUSS) with recursive calculation is used to alleviate the recovery error and reduce the computational cost, meanwhile the mismatch of space-time overcomplete dictionary is calibrated by minimized the cost function. Based on the simulated and the actual data, it is verified that the proposed method can not only converge with much smaller training samples compared with conventional STAP methods, but also provide improved performance compared with existing sparsity-based STAP methods.
This paper focuses on the signal modeling and character analysis in the passive radar system using global navigation satellite system (GNSS) satellites as illuminators of opportunity. The signal model derived from the...
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The range gate pull off (RGPO) jamming is considered as common electronic countermeasures (ECM) technique used to deceive radar tracking system. Under the stationary assumption, traditional slow-time pulse diversity a...
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ISBN:
(纸本)9781849199940
The range gate pull off (RGPO) jamming is considered as common electronic countermeasures (ECM) technique used to deceive radar tracking system. Under the stationary assumption, traditional slow-time pulse diversity approach needs several pulse repetition intervals (PRIs). However in the presence of RGPO, jamming signals would change fast over PRIs, making stationary hypothesis invalid. Therefore in order to solve this problem, a jamming cancelation approach based on the theory of pulse diversity is proposed in this paper to suppress deception RGPO jamming. In the proposed method, different from the conventional slow-time method, the proposed joint slow/fast time method implements a transmission pulse block in half quantity of PRI, which is designed based on the orthogonal block structure. Then after a simple one-step matched-filtering operation, jamming signal under RGPO can be suppressed efficiently. Since the cancellation process can be completed within one PRI, the stationary hypothesis is no longer needed. Based on the numeral simulations, it is verified that the proposed method is effective for countering RGPO jamming in rapidly changing condition.
Multi-frequency (MF) interferometric SAR (InSAR) provides an effective way for the surveying of steep terrains. Phase noise filtering is a key step in MF-InSAR processing which determines the quality of the interferog...
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