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IET International Radar Conference 2015

作者： Li, Shuling Zhao, Baojun Tang, Linbo Ji, Meiping School of Information and Electronic Beijing Institute of Technology China Beijing Key Laboratory of Embedded Real-Time Information Processing Technology China

ISBN: (纸本)9781849199940

A novel adaptive real-time image compression framework based on TMS320C6713 is presented in this paper. Via analyzing image texture, different compression ratio is applied for reducing the code stream. Owing to its low-cost, highspeed and low power performances, C6713 is selected as the main processor of framework. Firstly, the original image is transformed through lifting wavelet transform algorithm. Then, the resultant transformed data is encoded with zero tree wavelet, thereby completing the compression of 320x256 image with input bandwidth 2.34MB/s and output bandwidth 100kB/s. Moreover, the experimental results demonstrate that the adaptive image ratio can reach 25:1 with PSNR 30 and frame frequency can achieve 25fps with a high-speed processor.

关键词： Bandwidth

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Rearch on digital compensation technology of wideband Phased Array Radar based on chirp signal

Rearch on digital compensation technology of wideband Phased...

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IET International Radar Conference 2015

作者： Liu, Haibo Wang, E. Li, Jinbing Ren, Xiaoyuan School of Information and Electronics Beijing Institute of Technology Beijing China Beijing Key Laboratory of Embedded Real-Time Information Processing Technology China

ISBN: (纸本)9781849199940

A wideband PAR (Phased Array Radar) implementation framework based on wide band digital intermediate frequency is proposed for aperture full time problem. A method compensating the aperture full time by digital stretch processing for chirp signal is presented. A compensation approach for RF channels phase consistency using phase adjustment of digital oscillator is also given. Experiment results based on hardware system indicate that the method is effective and engineering realizable.

关键词： Radar

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Repeat-pass space-surface bistatic SAR tomography:accurate imaging and first experiment

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Science China(information Sciences) 2024年第9期67卷 245-262页

作者： Zhiyang CHEN Yuanhao LI Cheng HU Shenglei WANG Xinpeng CHEN Mihai DATCU Andrea Virgilio MONTI-GUARNIERI Radar Technology Research Institute School of Information and Electronics Beijing Institute of Technology Beijing Key Laboratory of Embedded Real-Time Information Processing Technology Beijing Institute of Technology Advanced Technology Research Institute Beijing Institute of Technology CEOSpace Tech University Politehnica of Bucharest Dipartimento di Elettronica Informazione e Bioingegneria Politecnico di Milano

Space-surface bistatic synthetic aperture radar(SS-BiSAR) offers an additional observation angle for monostatic spaceborne SAR, making it a promising technology for high-accuracy deformation retrieval technology in local regions. Repeat-pass SS-BiSAR tomography can accurately estimate the surfaces of buildings and steep areas, effectively removing terrain phases during deformation retrieving. However, inaccuracies in the orbital ephemeris can lead to image geometry distortion, reducing image pair coherence,introducing interferometric phase errors, and consequently deteriorating tomographic precision. This paper precisely models the image geometry distortion and interferometric phase error caused by repeat-pass ephemeris error. We propose an ephemeris correction method based on the chirp-Z transform to address these issues. Furthermore, we introduce an accurate tomography model to improve 3D reconstruction *** first SS-BiSAR tomography experiment, conducted using the Chinese Lutan-1 satellite, demonstrates that the correlation coefficient is improved by 0.16 after ephemeris error correction. Moreover, the density and precision of the tomographic point cloud are improved by 13.7% and 12.1%, respectively.

关键词： space-surface SAR tomography orbit error image distortion Lutan-1

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Derivative constrained Gram-Schmidt orthogonalization beamforming method with widened nulls

Derivative constrained Gram-Schmidt orthogonalization beamfo...

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IET International Radar Conference 2015

作者： Hu, Xiaona Song, Yuanyuan Sun, Yuze Yang, Xiaopeng Beijing Key Laboratory of Embedded Real-Time Information Processing Technology School of Information and Electronics Beijing Institute of Technology Beijing100081 China

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.

关键词： Covariance matrix

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A modified ISAR autofocus algorithm based on single eignvector

A modified ISAR autofocus algorithm based on single eignvect...

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2017 International Conference on Radar Systems, Radar 2017

作者： Cai, Jinjian Xu, Jia Sun, Yinghao Long, Teng Beijing Key Laboratory of Embedded Real-time Information Processing Technology School of Information and Electronics Beijing Institute of Technology Beijing100081 China

ISBN: (纸本)9781785615153

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 computational efficiency of single eigenvector based autofocusing method. Under the circumstance that a relatively prominent scatterer exists, it is found that the signal subspace can be obtained as an estimation of the phase error caused by target translational motion. In the proposed method, samplings in multiple pulses are used to construct the covariance matrix and obtain the signal subspace, which is equivalent to the existing method with samplings along multiple range bins. Finally, the results of real measured data are provided to demonstrate the effectiveness of the proposed method. © 2017 Institution of Engineering and technology. All rights reserved.

关键词： Computational efficiency

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Slow-time MIMO Radar Clutter Mitigation Based on Robust Pulse-to-Pulse Coding 6

Slow-Time MIMO Radar Clutter Mitigation Based on Robust Puls...

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6th Asia-Pacific Conference on Synthetic Aperture Radar, APSAR 2019

作者： Xu, Feng Xue, Junqi Yang, Xiaopeng Yang, Fawei Wang, Zhanze Beijing Key Laboratory of Embedded Real-time Information Processing Technology School of Information and Electronics Beijing Institute of Technology Beijing100081 China

ISBN: (纸本)9781728129129

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 deterioration of Signal to Noise Ratio (SNR) caused by superposition of clutter. To solve this problem, a robust pulse-to-pulse coding method is proposed to mitigate clutter as well as suppress the sidelobe level in Doppler domain. In our proposed method, the problem of optimizing weighting vector is transformed into a typical MVDR problem and the design of new weighting vector is obtained by the combination of MVDR solution and a sequence of weight coefficients which are calculated by Fourier inversion. This proposed method can mitigate the clutter adaptively while the sidelobe is suppressed. Both simulation and experiments results validate the reliability and effectiveness of this method. © 2019 IEEE.

关键词： MIMO radar

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Improved orthogonal projection adaptive beamforming based on normalization at subarray level

Improved orthogonal projection adaptive beamforming based on...

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IET International Radar Conference 2015

作者： Li, Shuai Yang, Xiaopeng Hu, Xiaona Guo, Liyong Beijing Key Laboratory of Embedded Real-Time Information Processing Technology School of Information and Electronics Beijing Institute of Technology Beijing100081 China

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.

关键词： Covariance matrix

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Low sidelobe beamforming method based on linear constraint reconstruction for colo-cated MIMO radar

Low sidelobe beamforming method based on linear constraint r...

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2017 International Conference on Radar Systems, Radar 2017

作者： Xu, Feng Yang, Xiaopeng Sun, Yuze Beijing Key Laboratory of Embedded Real-time Information Processing Technology School of Information and Electronics Beijing Institute of Technology Beijing100081 China

ISBN: (纸本)9781785615153

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 to achieve a better beam pattern performance for colocated MIMO radar, a low sidelobe beamforming method based on linear constraint reconstruction is proposed. In this proposed method, beam pattern nulls are formed in the specified direction of grating lobes by using reconstructed linear constraints, which can work with low sidelobe window function. These constraints are proper eigenvectors of reconstructed covariance matrix. Comparing with conventional method, arbitrary low sidelobe weight is applied instead of quiescent weight, thus the beam pattern can obtain low sidelobe level while maintaining the ability of anti-jamming. Simulation results verify the efficiency of this proposed method in both uniform array and sparse array. © 2017 Institution of Engineering and technology. All rights reserved.

关键词： MIMO radar

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Subarray partition method based on division position coding genetic algorithm

Subarray partition method based on division position coding ...

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IET International Radar Conference 2015

作者： Xi, Wen Yang, Xiaopeng Sun, Yuze Zeng, Tao Beijing Key Laboratory of Embedded Real-Time Information Processing Technology School of Information and Electronics Beijing Institute of Technology Beijing100081 China

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.

关键词： Genetic algorithms

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Iterative roubust sparse recoery method based on FOCUSS for space-time adaptive processing

Iterative roubust sparse recoery method based on FOCUSS for ...

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IET International Radar Conference 2015

作者： Yang, Xiaopeng Sun, Yuze Zeng, Tao Long, Teng Beijing Key Laboratory of Embedded Real-Time Information Processing Technology School of Information and Electronics Beijing Institute of Technology Beijing100081 China

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.

关键词： Space time adaptive processing

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