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High accuracy unambiguous angle estimation using multi-scale combination in distributed coherent aperture radar

IET RADAR SONAR AND NAVIGATION 2017年第7期11卷 1090-1098页

作者： Long, Teng Zhang, Honggang Zeng, Tao Liu, Quanhua Chen, Xinliang Zheng, Le Beijing Inst Technol Sch Informat & Elect Radar Res Lab Beijing Key Lab Embedded Real Time Informat Proc Beijing 100081 Peoples R China Columbia Univ Dept Elect Engn New York NY 10027 USA

Distributed coherent aperture radar (DCAR) can realise N-3 times signal-to-noise ratio promotion, as well as achieve high accuracy angle estimation since it has an equivalent large aperture. However, due to its sparse array, grating lobes are emerged in antenna pattern, which will lead to ambiguous angle estimation. Based on the various degrees of freedom of DCAR, this study proposes a multi-scale combination method to disambiguate the correct angle from the ambiguous ones. Firstly, it combines the antenna in different scale, so each combination has different equivalent phase centre spacings. Secondly, phase comparison monopulse is employed to measure the angles under each combination with relatively low computational complexity, even in the single snapshot scenario. Thirdly, the high accuracy unambiguous angle can be resolved from the low accuracy unambiguous angle step by step. Moreover, the estimation accuracy and design criterion on correct angle extraction are also analysed, providing an array geometry and combination design approach to guarantee the disambiguity process a success. Finally, DCAR with two radars and eight radars are properly designed, respectively, and simulations and field experiments validate the effectiveness of the proposed method.

关键词： radar antennas computational complexity antenna radiation patterns estimation theory high accuracy unambiguous angle estimation multiscale combination method distributed coherent aperture radar DCAR signal-to-noise ratio grating lobes sparse array antenna pattern equivalent phase centre spacings phase comparison monopulse computational complexity design criterion angle extraction array geometry combination design approach disambiguity process degrees of freedom

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Azimuth Location Deambiguity for SAR Ground Moving Targets via Coprime Adjacent Arrays

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IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING 2018年第2期11卷 551-561页

作者： Huang, Zu-Zhen Ding, Ze-Gang Xu, Jia Zeng, Tao Liu, Li Wang, Zhi-Rui Feng, Chang-Hui Beijing Inst Technol Sch Informat & Elect Beijing Key Lab Embedded Real Time Informat Proc Beijing 100081 Peoples R China Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China Wuhan Second Ship Design & Res Inst Wuhan 430205 Hubei Peoples R China

The ground moving target's radial velocity estimation based on the interferometric phase in a multichannel synthetic aperture radar (SAR) system suffers from 2p modulo folding, resulting in the target's azimuth location ambiguity in the SAR image. To address this problem, a novel coprime adjacent arrays SAR (CAA-SAR) is proposed in this paper. The two sparse uniform subarrays constituting the CAA are arranged adjacently with a conjunct element, then a virtual array can be obtained with muchmore virtual elements and smaller element spacing, which will help to solve the azimuth location ambiguity. After ground clutter suppression, multiple pixels' samplings are utilized based on the MUSIC algorithm for estimating radial velocity as well as azimuth shift by exploiting all virtual elements of CAA-SAR. Compared with the existing nonuniform linear array SAR method based on Chinese remainder theorem, the CAA-SAR can obtain a better accuracy with the same number of elements in a larger sparse configuration, or use fewer elements to obtain an approximate accuracy in almost the same physical aperture. Compared with the coprime arrays SAR, the CAA-SAR has a better accuracy due to its larger number of unique virtual elements and longer physical aperture. Finally, some results of numerical experiments are provided to demonstrate the effectiveness of the proposed method.

关键词： Azimuth location ambiguity coprime adjacent arrays ground moving target indication (GMTI) synthetic aperture radar (SAR)

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Effect Analysis of Antenna Vibration on GEO SAR Image

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2020年第3期56卷 1708-1721页

作者： Long, Teng Zhang, Tianyi Ding, Zegang Yin, Wei Beijing Inst Technol Radar Res Lab Sch Informat & Elect Beijing 10081 Peoples R China Beijing Inst Technol Beijing Key Lab Embedded Real Time Informat Proc Beijing 10081 Peoples R China China Elect Technol Grp Corp Res Inst 54 Shijiazhuang 050081 Hebei Peoples R China

Existing effect analyses of antenna vibration (AV) on synthetic aperture radar (SAR) image, which are all aimed for low-earth-orbit SAR and based on the linear trajectory, second-order azimuth spectrum, and range time-invariant as well as azimuth time-variant antenna gain, are not feasible in geosynchronous SAR (GEO SAR), because GEO SAR has an obviously curved trajectory, high-order azimuth spectrum, and two-dimensional (2-D) time-variant antenna gain. To overcome these problems and analyze the effects of AV on GEO SAR image, a modified analysis is proposed in this paper. First, based on the curved trajectory, the high-order ideal echo signalmodel and the ideal point spread function (PSF) of GEO SAR are, respectively, established and deducted, and the AV that consists of antenna translational vibration (ATV) and antenna rotation motion (ARV) and the 2-D time-variant antenna gain in squint mode are also, respectively, modeled. Then, based on the series expansion, the paired echo theory, and the aforementioned models, the echo signal model affected by ATV, the corresponding PSF affected by ATV, the antenna gain model affected by ARV, and the corresponding PSF affected by ARV are obtained, and the effects of ATV and ARV on GEO SAR image are, respectively, analyzed in detail. Compared with existing effect analyses of AV on SAR image, the modified analysis considers the influences of curved trajectory, high-order azimuth spectrum, and 2-D time-variant antenna gain simultaneously, and it has much more accuracy and adaptability correspondingly. Finally, computer simulations validate the correctness of the proposed analysis.

关键词： Azimuth Synthetic aperture radar Antennas Radar polarimetry Analytical models Trajectory Vibrations

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M-FCN: Effective Fully Convolutional Network-Based Airplane Detection Framework

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IEEE GEOSCIENCE AND REMOTE SENSING LETTERS 2017年第8期14卷 1293-1297页

作者： Yang, Yiding Zhuang, Yin Bi, Fukun Shi, Hao Xie, Yizhuang Beijing Inst Technol Sch Informat & Elect Radar Res Lab Beijing Key Lab Embedded Real Time Informat Proc Beijing 100081 Peoples R China North China Univ Technol Sch Elect Informat Engn Beijing 100144 Peoples R China Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China

Airplane detection is a challenging problem in complex remote sensing imaging. In this letter, an effective airplane detection framework called Markov random field-fully convolutional network (M-FCN) is proposed. The M-FCN uses a cascade strategy that consists of an FCN-based coarse candidate extraction stage, a multi-Markov random field (multi-MRF)-based region proposal (RP) generation stage, and a final classification stage. In the first stage, the FCN model is trained to be sensitive to airplanes, and a coarse candidate map is generated. This model is scale-, direction-, and color-invariant and does not require many training examples. After the first stage, the coarse candidate map is used as the initial labeling field for a multi-MRF algorithm, and RPs are generated according to the multi-MRF output. This RP-generating strategy can yield more accurate locations with fewer RPs. In the last stage, a convolutional neural network-based classifier is used to improve the precision of the entire framework. Experiments show that the M-FCN has high precision, recall, and location accuracy.

关键词： Fully convolutional network (FCN) Markov random field (MRF) object detection remote sensing

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High-resolution velocity-azimuth joint estimation for random-time-division-multiplexing multiple-input-multiple-output automotive radar using matrix completion

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IET RADAR SONAR AND NAVIGATION 2021年第10期15卷 1281-1296页

作者： Hu, Xueyao Zhang, Liang Long, Jiamin Liang, Can Liu, Jianhu Wang, Yanhua Beijing Inst Technol Sch Informat & Elect Radar Res Lab Beijing 100081 Peoples R China Chongqing Innovat Ctr Beijing Inst Technol Chongqing 401120 Peoples R China Beijing Key Lab Embedded Real Time Informat Proc Beijing Peoples R China Beijing Rxbit Elect Technol Co Ltd Beijing Peoples R China

Due to its low hardware complexity, small volume and simple structure, time-division-multiplexing multiple-input-multiple-output (TDM MIMO) radar has been widely applied in automotive applications. The transmitting antennas of TDM MIMO automotive radar are usually switched according to a sequential-TDM pattern. However, moving targets can introduce a motion-induced phase into the sequential-TDM pattern, which is coupled to the spatial phase, resulting in errors in velocity and azimuth estimation. Herein, a random-TDM pattern with the matrix completion (MC)-based estimation method is proposed to address these issues. In the proposed method, the random-TDM pattern, which means randomly activating the transmitting antenna instead of sequentially, can decouple the linear temporal-spatial coupling phase, avoiding the coupling problem in velocity and azimuth estimation. Then, by reshaping the echo data into a matrix form of sparse sampling, the inexact augmented Lagrange multiplier algorithm is adopted to recover this matrix, solving the underdetermined estimation problem caused by sparse sampling. Finally, the high-accuracy velocity and azimuth can be jointly estimated by applying the estimation of signal parameters via rotational invariance technique algorithm to the recovered full sampling data. Moreover, compared with the compressed sensing-based method, the proposed method overcomes the grid mismatch problem. The results of comparative simulations and real-data experiments demonstrate the feasibility of the proposed method.

关键词： radar signal processing Radar theory full sampling data rotational invariance technique algorithm Communication switching matrix form inexact augmented Lagrange multiplier algorithm echo data velocity estimation Linear algebra (numerical analysis) multiple-input-multiple-output automotive radar Optimisation techniques signal parameters estimation Signal processing and detection coupling problem randomly activated transmitting antennas random-time-division-multiplexing automotive radar optimisation matrix algebra Other topics in statistics sparse sampling Radar equipment, systems and applications velocity measurement Automobile electronics Velocity, acceleration and rotation measurement transmitting antennas road vehicle radar matrix completion-based estimation method linear temporal-spatial coupling phase estimation theory azimuth estimation Antenna arrays random-TDM pattern array signal processing grid mismatch problem time division multiplexing radar antennas TDM MIMO radar high-resolution velocity-azimuth joint estimation MIMO radar underdetermined estimation problem

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Signal Modeling and Experimental Verification in GNSS Forward Scatter Radar

Signal Modeling and Experimental Verification in GNSS Forwar...

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17th International Radar Symposium (IRS)

作者： Liu Changjiang Hu Cheng Zeng Tao Wang Li Long Teng Beijing Inst Technol Dept Elect & Informat Beijing Key Lab Embedded Real Time Informat Proc Beijing 100081 Peoples R China

ISBN: (纸本)9781509025183

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 GNSS tracking loop shows that it contains information of both the scatter coefficient and the signal Doppler. An experiment using metal board as target was carried out and the results verified the correctness of the given model.

关键词： GNSS forward satter Doppler tracking loop

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Sea-Land Segmentation for Panchromatic Remote Sensing Imagery via Integrating Improved MNcut and Chan-Vese Model

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IEEE GEOSCIENCE AND REMOTE SENSING LETTERS 2017年第12期14卷 2443-2447页

作者： Liu, Wenchao Ma, Long Chen, He Han, Zhong Soomro, Nouman Q. Beijing Inst Technol Beijing Key Lab Embedded Real Time Informat Proc Beijing 100081 Peoples R China Zhengzhou Univ Sch Informat Engn Zhengzhou 450001 Henan Peoples R China Mehran Univ Engn & Technol Dept Software Engn Khairpur 66020 Pakistan

Sea-land segmentation is a key step for some important applications of panchromatic remote sensing image processing. However, robust and effective sea-land segmentation for high-resolution panchromatic remote sensing images is still a challenging problem. This letter presents an accurate and robust approach by integrating the improved multiscale normalized cut (IMNcut) method and improved Chan-Vese model for sea-land segmentation. At first, the image is downsampled and segmented into multiple regions by the IMNcut method. Next, the homogeneous regions are merged to obtain a coarse segmentation result. Finally, gray intensity and local entropy features are integrated as discriminants of the improved Chan-Vese model, which is used to obtain the final segmentation result through a low-to high-resolution segmentation scheme. Experimental results performed on several real data sets demonstrate the effectiveness of the proposed model in terms of visual and objective evaluations.

关键词： Chan-Vese model multiscale normalized cut (MNcut) panchromatic remote sensing image sea-land segmentation

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Computerized ionospheric tomography based on geosynchronous SAR

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JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 2017年第2期122卷 2686-2705页

作者： Hu, Cheng Tian, Ye Dong, Xichao Wang, Rui Long, Teng Beijing Inst Technol Sch Informat & Elect Beijing Peoples R China China Acad Elect & Informat Technol Beijing Peoples R China Tsinghua Univ Dept Elect Engn Beijing Peoples R China Embedded Real Time Informat Proc Technol Beijing Key Lab Beijing Peoples R China

Computerized ionospheric tomography (CIT) based on spaceborne synthetic aperture radar (SAR) is an emerging technique to construct the three-dimensional (3-D) image of ionosphere. The current studies are all based on the Low Earth Orbit synthetic aperture radar (LEO SAR) which is limited by long repeat period and small coverage. In this paper, a novel ionospheric 3-D CIT technique based on geosynchronous SAR (GEO SAR) is put forward. First, several influences of complex atmospheric environment on GEO SAR focusing are detailedly analyzed, including background ionosphere and multiple scattering effects (induced by turbulent ionosphere), tropospheric effects, and random noises. Then the corresponding GEO SAR signal model is constructed with consideration of the temporal-variant background ionosphere within the GEO SAR long integration time (typically 100 s to 1000 s level). Concurrently, an accurate total electron content (TEC) retrieval method based on GEO SAR data is put forward through subband division in range and subaperture division in azimuth, obtaining variant TEC value with respect to the azimuth time. The processing steps of GEO SAR CIT are given and discussed. Owing to the short repeat period and large coverage area, GEO SAR CIT has potentials of covering the specific space continuously and completely and resultantly has excellent real-time performance. Finally, the TEC retrieval and GEO SAR CIT construction are performed by employing a numerical study based on the meteorological data. The feasibility and correctness of the proposed methods are verified.

关键词： geosynchronous SAR ionosphere computerized ionospheric tomography remote sensing

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MULTI-TEMPORAL IMAGES GENERATION FOR BUILDING CHANGE DETECTION PERFORMANCE PROMOTION

MULTI-TEMPORAL IMAGES GENERATION FOR BUILDING CHANGE DETECTI...

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IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Li, Yute Li, Wei Wang, Nan Gao, Chenzhong Zhuang, Yin Chen, He Beijing Inst Technol Beijing Key Lab Fract Signals & Syst Beijing 100081 Peoples R China Beijing Inst Technol Beijing Key Lab Embedded Real Time Informat Proc Beijing 100081 Peoples R China

ISBN: (纸本)9798350360332;9798350360325

The changes in building are important basis for urban monitoring. However, due to the rarity and sparsity of the occurrence of changes in buildings, collecting effective bitemporal image pairs is challenging, as it requires long-term observation over several months or even years. Additionally, annotating large-scale change detection datasets is time-consuming and labor-intensive. Consequently, data scarcity issues lead to insufficient training of building change detection models. To address this, we propose a data generation method Building Generation GAN (BG-GAN). Different from other GANs, the BG-GAN is trained based on adversarial consistency loss, enabling the model to generate new bi-temporal image pairs with various types of building changes. To verify the effectiveness of the proposed methods on change detection task, BG-GAN is utilized to perform building change samples generation on two building change detection datasets ( LEVIR-CD and WHU-CD). The experimental results demonstrate that the proposed method can improve the robustness and generalization of change detection model to detect pseudo changes.

关键词： Change detection Generative adversarial networks Data generation

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Non-Contact Vibration Retrieval and Performance Analysis Based on LFMCW Radar

Non-Contact Vibration Retrieval and Performance Analysis Bas...

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IEEE International Conference on Signal processing, Communications and Computing (ICSPCC)

作者： Liao, Xin Liu, Shuai Xiang, Yin Ding, Zegang Yan, Xuemei Beijing Inst Technol Sch Informat & Elect Beijing Key Lab Embedded Real Time Informat Proc Beijing Peoples R China CAST Beijing Inst Spacecraft Syst Engn Beijing Peoples R China

ISBN: (纸本)9781509027088

In the paper, a non-contact vibration retrieval method was presented and the performance was analyzed based on linear frequency modulation continuous wave (LFMCW) radar. Firstly, the backscattered signal model of a vibrational target was introduced with the stop-go assumption. Then a vibration retrieval method was proposed by extracting phase based on the backscattered signal model of a vibrational target. The influence of noise and clutter on vibration retrieval was analyzed, and the signal noise ratio of vibration measurement was obtained. Finally, the validity of the performance analysis was verified by computer simulations. In addition, the experimental data acquired by LFMCW radar was used to test the proposed method.

关键词： non-contact vibration retrieval SNR LFMCW phase extraction

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