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| Special Topic Papers: Frequency Diverse Array Radar |
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153 |
Wang Wenqin, Chen Hui, Zheng Zhi, Zhang Shunsheng |
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Advances on Frequency Diverse Array Radar and Its Applications |
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Unlike the conventional phased array that provides only angle-dependent transmit beampattern, Frequency Diverse Array (FDA) employs a small frequency increment across its array elements to produce automatic beam scanning without requiring phase shifters or mechanical steering. FDA can produce both range-dependent and time-variant transmit beampatterns, which overcomes the disadvantages of conventional phased arrays that produce only angle-dependent beampattern. Thus, FDA has many promising applications. Based on a previous study conducted by the author, "Frequency Diverse Array Radar:Concept, Principle and Application" (Journal of Electronics & Information Technology, 2016, 38(4):1000-1011), the current study introduces basic FDA radar concepts, principles, and application characteristics and reviews recent advances on FDA radar and its applications. In addition, several new promising applications of FDA technology are discussed, such as radar electronic warfare and radar-communications, as well as open technical challenges such as beampattern variance, effective receiver design, adaptive signal detection and estimation, and the implementation of practical FDA radar demos.
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2018 Vol. 7 (2): 153-166
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1268
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1958
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183 |
Chen Xiaolong, Chen Baoxin, Huang Yong, Xue Yonghua, Guan Jian |
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Frequency Diverse Array Radar Signal Processing via Space-Range-Doppler Focus (SRDF) Method |
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To meet the urgent demand of low-observable moving target detection in complex environments, a novel method of Frequency Diverse Array (FDA) radar signal processing method based on Space-Rang-Doppler Focusing (SRDF) is proposed in this paper. The current development status of the FDA radar, the design of the array structure, beamforming, and joint estimation of distance and angle are systematically reviewed. The extra degrees of freedom provided by FDA radar are fully utilizsed, which include the Degrees Of Freedom (DOFs) of the transmitted waveform, the location of array elements, correlation of beam azimuth and distance, and the long dwell time, which are also the DOFs in joint spatial (angle), distance, and frequency (Doppler) dimensions. Simulation results show that the proposed method has the potential of improving target detection and parameter estimation for weak moving targets in complex environments and has broad application prospects in clutter and interference suppression, moving target refinement, etc..
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2018 Vol. 7 (2): 183-193
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355
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[PDF 1533KB]
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1280
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194 |
Gong Pengcheng, Liu Gang, Huang He, Wang Wenqin |
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Multidimensional Parameter Estimation Method Based on Sparse Iteration in FDA-MIMO Radar |
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To accurately identify the range of each target, traditional Multiple-Input Multiple-Output (MIMO) radar techniques not only require designing a shift matrix to describe different range bins but also a large number of snapshots.To alleviate this problem, a multidimensional parameter estimation method based on sparse iteration is proposed for a MIMO radar with Frequency Diverse Array (FDA).The FDA-MIMO radar uses small frequency increments across the array elements, and its transmit steering vector is a function of both range and angle.On the basis of the feature of the FDA-MIMO radar, we consider a weighted lq (0 < q ≤ 1) minimization problem that is solved using a sparse iterative algorithm.Finally, the target parameters (the amplitude, range, and angle) are obtained using a single snapshot.Moreover, numerical simulations are used to demonstrate the superior performance of the proposed method compared with those of DAS, IAA, and IAA-R.
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2018 Vol. 7 (2): 194-201
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484
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[PDF 4640KB]
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1125
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244 |
Li Hangjian, Wang Robert, Deng Yunkai, Wang Wei, Zhang Heng |
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Analysis of Time and Beam Synchronization Errors for Distributed Spaceborne SAR System |
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Synchronization is a key problem in distributed Synthetic Aperture Radar (SAR) systems. In this paper, we perform a complex mathematical deduction and then analyze the influences of time synchronization on the SAR imaging and interferometric process. We discuss the relationship between time and phase synchronization, considering that different oscillators in separated transmitters and receivers lead to both time and phase synchronization errors. With respect to beam synchronization, we present the effects of the accuracies of beam pointing and satellite attitude on the antenna gain, based on the attitude-steering strategy, which involves azimuth weighting of the Doppler spectra for independent zero-Doppler beam steering. We also analyze the influences of beam synchronization on Doppler decorrelation, Signal-to-Noise Ratio (SNR), and overlapping swath error. We conduct simulations to validate the analysis results. Our findings provide guidance for system design.
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2018 Vol. 7 (2): 244-253
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326
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[PDF 21498KB]
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901
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254 |
Li Yangyang, Li Wen, Yi Wei, Kong Lingjiang |
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A Distributed Asynchronous Recursive Filtering Fusion Algorithm via DP-TBD |
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In this paper, we address target tracking problems by the use of multiple sensors via the Dynamic Programming (DP)-based Track-Before-Detect (TBD) method. Generally, DP-TBD is a grid-based method that estimates target trajectories by searching all the physically admissible paths in a determinate discrete state space. However, this multi-frame detection algorithm provides plot sequences without filtering or smoothing. With the growing complexity of the battle field environment, single radar based on DP-TBD cannot achieve satisfactory results when the Signal-to-Noise Ratio (SNR) is low. Besides, it is very difficult to fuse plot sequences from different radars because they contain no state error covariance matrix. Furthermore, various radars always contain asynchronous data due to the diversity of sampling times and communication delays. To alleviate these problems, we propose a distributed asynchronous recursive filtering fusion (Dynamic Programming Fuison, DPF) algorithm based on DP-TBD, which is divided into two steps. In the first step, we propose an iterative filter algorithm via DP-TBD. Then, we convert the asynchronous evaluation data into synchronous data and implement several distributed fusion algorithms to estimate the target state. Simulation results show that the proposed algorithm can correctly estimate target trajectories and significantly enhance tracking accuracy compared to solo radar. In addition, this algorithm can decrease the track loss rate and calculation burden.
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2018 Vol. 7 (2): 254-262
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455
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[PDF 859KB]
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733
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