IET Radar, Sonar & Navigation
Volume 12, Issue 9, September 2018
Volumes & issues:
Volume 12, Issue 9
September 2018
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- Author(s): Jarez S. Patel ; Francesco Fioranelli ; David Anderson
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 911 –919
- DOI: 10.1049/iet-rsn.2018.0020
- Type: Article
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This review explores radar-based techniques currently utilised in the literature to monitor smallunmanned aerial vehicle (UAV) or drones; several challenges have arisen due to their rapid emergenceand commercialisation within the mass market. The potential security threats posed by these systemsare collectively presented and the legal issues surrounding their successful integration are brieflyoutlined. Key difficulties involved in the identification and hence tracking of these ‘radarelusive’ systems are discussed, along with how research efforts relating to drone detection,classification and radar cross section (RCS) characterisation are being directed in order to addressthis emerging challenge. Such methods are thoroughly analysed and critiqued; finally, an overallpicture of the field in its current state is painted, alongside scope for future work over a broadspectrum.
Review of radar classification and RCS characterisation techniques for small UAVs ordrones
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- Author(s): Jungshin Lee and Hyochoong Bang
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 920 –930
- DOI: 10.1049/iet-rsn.2018.0079
- Type: Article
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The purpose of this study is to propose a measurement classification method necessary to implement precision terrain-aided navigation (TAN) by using an interferometric radar altimeter (IRA) as a technology that can replace global positioning system/inertial navigation system integrated navigation. IRA is a sensor that extracts the angle perpendicular to the direction of flight, the look angle, and the slant range from the aircraft to the nearest terrain point. Unlike the radio altimeter which only measures the direct downward distance, IRA can be converted into three-dimensional coordinates in the navigation system. However, the IRA output has a disadvantage that it has uncertainty that cannot be predicted due to the signal processing and environmental factors. Therefore, a useful navigation technique for classifying sensor outputs is needed to implement precision TAN. This study introduces the radial basis function network and extreme learning machine methods to classify available IRA measurements and verifies the suitability of the proposed classification method by applying it to the bank of Kalman filter) and particle filter-based TAN.
- Author(s): Hossein Darvishi and Mohammad Ali Sebt
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 931 –937
- DOI: 10.1049/iet-rsn.2018.5114
- Type: Article
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Tracking low-angle targets is a serious problem in radar systems because of the multipath phenomenon. When a signal is reflected from the ground surface, due to the low altitude of the target, it enters the radar main beam and seriously reduces its performance. The authors propose a novel adaptive hybrid method based on the complex angle (CA) method and the array monopulse system. They present a way to reduce the ambiguity of the CA method, and then, eliminate the multipath effect by using beamforming and provide an accurate estimate of the elevation angle. The simulation results show the performance of this method in tracking low-angle targets.
- Author(s): Shuai Jiang ; Bingnan Wang ; Maosheng Xiang ; Xikai Fu ; Xiaofan Sun
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 938 –944
- DOI: 10.1049/iet-rsn.2018.5118
- Type: Article
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Current navigation systems have a number of drawbacks including no cross-line resolution in terrain-aided navigation; scene matching affected by seasonal changes; terrain-aided navigation and synthetic aperture radar (SAR)-aided navigation system cannot adapt to rugged terrain. Therefore, this study proposes an integrated interferometric SAR-aided inertial navigation system (InSAR/INS) based on interferogram matching. Terrain undulation and platform attitude can be reflected in the interferometric phase; hence, interferogram matching can provide location shift information. The authors introduce InSAR/INS processing flow, interferogram matching theory, and attitude and position inversion models. Experimental results verify that the proposed approach inverses attitude and position with high precision, and confirm the validity of the proposed InSAR/INS approach.
- Author(s): Yuan Huang ; Taek Lyul Song ; Da Sol Kim
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 945 –953
- DOI: 10.1049/iet-rsn.2017.0481
- Type: Article
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The point target assumption, which suggests that a target can generate at most one measurement at a time, is used in typical target tracking algorithms. However, in many practical applications, multiple scattering points of a target can be resolved using a high-resolution sensor, which gives rise to the multiple detection problem. The typical algorithms with the point target assumption are not eligible for multiple detection tracking environments. The multiple detection joint integrated probabilistic data association algorithm is designed to solve the multiple detection multitarget tracking problem. However, the computational complexity of this algorithm grows exponentially with the number of tracks and measurement cells. Here, multiple detection linear multitarget integrated probabilistic data association is proposed to enhance computational efficiency by introducing the modulated clutter measurement density, which takes into account the contributions of clutter as well as other targets of each measurement cell. The computational complexity of the proposed algorithm is linear in the number of tracks and the number of measurement cells. Simulation results verify the applicability and efficiency of the proposed algorithm in multiple detection multitarget tracking scenarios.
- Author(s): Yunhan Dong
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 954 –963
- DOI: 10.1049/iet-rsn.2018.0031
- Type: Article
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The frequency diverse array (FDA) radar is re-explored with a special focus on how the FDA data should be correctly and efficiently processed to maximise its full potential and capacity of search and detection. Some features, such as its extraordinary Doppler tolerance and ability of resolving range ambiguity without using multiple pulse repetition frequencies, are first demonstrated. The extension of non-linear and random frequency increments is proposed in order to suppress range sidelobes and increase range resolution. Wide-area search and detection is achieved by processing the same received data set without a need of electronic scan and repeat pulse transmission and reception. This not only greatly simplifies the radar design and operation but also makes radar quieter and stealth. The limitation of the FDA radar is its sacrificed detection range. Therefore, in comparison with the conventional phased-array radar, the detection area is fan-area-like for the former and pencil-beam-like for the latter, making two radars (or radar operation modes) complementary.
- Author(s): Chibiao Ding ; Tingting Jin ; Xiaolan Qiu ; Donghui Hu
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 964 –972
- DOI: 10.1049/iet-rsn.2017.0512
- Type: Article
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Velocity estimation of a moving target is an important yet challenging issue facing the special mode of high-resolution and wide-swath (HRWS) synthetic aperture radar. HRWS imaging is achieved by splitting the antenna into multiple receive channels in azimuth with each channel working at low pulse repetition frequency sampling. In this study, the authors propose a novel approach to estimate the velocity of a moving target in HRWS mode, along with a complete moving target indication, estimation, and imaging scheme. The proposed radial velocity estimation algorithm is called the equivalent along-track interferometry method, which is implemented by twice imaging after reconstructing the data of several leftmost and rightmost channels. Moreover, the along-track velocity is also estimated for focused imaging of the moving target. The motion-adapted reconstruction and imaging algorithm is applied to achieve unambiguous imaging of the moving target. Experimental results verify the performance of the algorithm and its superiority for a moving target with interference from clutter, noise, and channel mismatches. The proposed algorithm is free of search and iteration, and featured by high accuracy and low computational load.
- Author(s): Guowei Yao ; Junhao Xie ; Weimin Huang
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 973 –978
- DOI: 10.1049/iet-rsn.2018.0099
- Type: Article
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To investigate the characteristic of ocean surface backscatter echo, the first-order ocean surface cross-section for shipborne high-frequency surface wave radar (HFSWR) incorporating a horizontal oscillation motion model is mathematically derived. The horizontal oscillation motion includes yaw, sway and surge. Simulation results show that the horizontal oscillation motion can induce more additional peaks in Doppler spectrum due to combined oscillation motions, and the amplitudes as well as frequency locations of these motion-induced peaks are determined by the amplitude and frequency of the oscillation motion. Furthermore, the Bragg and motion-induced peaks are spread due to the forward movement of the ship. These spreading peaks overlap each other as the ship speed increases, which may severely influence moving target detection and ocean remote sensing. However, different characteristics of the first-order cross-sections for the true and ambiguous wind directions provide a new idea to measure ocean surface wind direction by shipborne HFSWR with a single receiving antenna.
- Author(s): Shahabuddin Rahmanian ; Mohammad Hossein Bateni ; Majdeddin Najafi
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 979 –987
- DOI: 10.1049/iet-rsn.2018.0072
- Type: Article
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Typical tracking systems employ tracking filters in order to consecutively estimate the kinematics of a moving object, based on some limited observations of its position and/or velocity which are contaminated by different types of uncertainties. The Kalman filter is the optimal filter for some simple cases. However, in practical scenarios, designing more complicated filters or making modifications to the Kalman filter may be necessary, in order to provide the tracking process with adequate reliability and accuracy. An appropriate design should consider the discipline under which measurements are gathered and the type of disturbances to which the measurement process is exposed. This study investigates the case of quantised, unreliable, asynchronous velocity and position measurements, and proposes an effective design which realises a distributed Kalman filter with two- or three-dimensional state vectors. It is shown via simulations that the proposed design not only smooths the output and combats the effects of quantisation but also keeps on tracking when the measurements are lost for a quite long duration of time.
- Author(s): Zhichun Zhao ; Ran Tao ; Gang Li ; Yue Wang
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 988 –997
- DOI: 10.1049/iet-rsn.2017.0550
- Type: Article
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Inverse synthetic aperture radar (ISAR) is an effective radar imaging technology to obtain high-resolution images of manoeuvring targets. To improve the cross-range resolution of ISAR images, a fractional sparse energy representation method is proposed for ISAR imaging of rotating targets by combining fractional Fourier transform with sparse representation technique. Experimental results demonstrate that the proposed algorithms can efficiently realise high-quality imaging in addition to robustness against noise.
- Author(s): Khaled Obaid Al Ali ; Nemanja Ilić ; Miloš S. Stanković ; Srdjan S. Stanković
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 998 –1004
- DOI: 10.1049/iet-rsn.2018.5127
- Type: Article
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The authors propose a new algorithm for distributed target tracking by sensor networks with sensors having limited sensing range (radars, sonars, cameras), using an adaptive multi-step consensus scheme. The proposed distributed adaptation strategy represents the core element of the algorithm, providing: (i) asymptotic consensus gains giving the desired importance to the nodes observing the target, and (ii) fast convergence rate of the consensus scheme, enabling efficient implementation. Another contribution of this study is a theoretical study of the algorithm properties, including asymptotic stability and reduction of noise influence. The given simulation results show that the proposed algorithm outperforms the existing algorithms, preserving, at the same time, much lower communication and computation requirements.
- Author(s): Kun-Yi Guo ; Tong-Yao Niu ; Xin-Qing Sheng
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 1005 –1011
- DOI: 10.1049/iet-rsn.2018.0012
- Type: Article
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Attributed scattering centres (SCs) of real radar targets are far more complex than ideal scatterers; their scattering amplitudes and locations are dependent on aspect angle, frequency and polarisation in different ways. Numerical results present in this work show that the reconstructed locations of the SCs by using monopulse radar are closely related with the aspect dependencies of the SCs. The influence on location reconstructions by aspect dependencies are investigated, and it is found that distributed SCs (DSCs) generally cause more serious errors in the reconstructed results than other types of SCs. To deal with this, a simple approach is presented, where the range profile (RP) with DSCs is discriminated from other RPs, and only the highest peak is selected as a true scattering source to be reconstructed. Two extended targets and a group of three targets are investigated for validation, and the results show good agreement between the numerical and analytical results, and the availability of this approach.
- Author(s): Yan Wang ; Yuliang He ; Jinjin Wang ; Zhibo Shi
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 1012 –1020
- DOI: 10.1049/iet-rsn.2018.0039
- Type: Article
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The active sonar detection performance in shallow water is mainly restricted by the reverberation level. When target echoes are separable from reverberation according to Doppler shifts, comb waveforms with the bed-of-nails ambiguity function can achieve reverberation suppression. However, some comb waveforms present significantly low transmitting efficiency measured by the high peak-to-average power ratio (PAPR), which may severely affect the detection performance in a noise-limited scenario. In order to effectively improve their transmitting efficiency, the authors propose an approach of comb waveform optimisation with low PAPR via alternating projection in this study. The main idea is based on designing projection constraint sets and corresponding projection operators to achieve the shaping of comb spectra. Hence, the approach has the capability to make a compromise between the transmitting efficiency and reverberation suppression performance. The PAPR control of geometric comb waveforms is implemented in simulations, which prove the validity of the approach.
- Author(s): Hongyan Wang
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 1021 –1027
- DOI: 10.1049/iet-rsn.2018.5113
- Type: Article
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The issue of robust orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) radar waveform design is investigated here with target uncertainty to enhance the worst-case space-time adaptive processing (STAP) detection performance of MIMO–OFDM radar. Based on the max–min method, the robust waveform optimisation problem is constructed under the criterion of maximising the worst-case output SINR, namely, signal–interference–noise ratio, with constraints of constant modulus and target estimation errors to enhance the robustness of STAP's detection performance to target uncertainty. To handle the obtained non-linear and complicated issue, an approach based on diagonal loading (DL) is presented. By employing DL method, the optimisation issue can be relaxed to semidefinite programming one, and thus it can be tackled very efficiently. When compared with uncorrelated signals, the state-of-the-art robust and non-robust waveform design methods for MIMO–STAP, numerical simulations reveal that the developed approach can enhance the robustness of the detection performance of STAP significantly.
- Author(s): Qiang Wu ; Jiansheng Zheng ; Zhicheng Dong ; Mingkun Su ; Hexi Liang ; Ping Zhang
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 1028 –1037
- DOI: 10.1049/iet-rsn.2018.5175
- Type: Article
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The authors aim at providing an interference detection algorithm for global navigation satellite system (GNSS) receivers based on the adaptive subspace tracking technique and receiver autonomous integrity monitoring (RAIM). A complete framework, including an estimator used to determine the number of interference sources and a method for detecting the interference frequency, is presented in the narrowband interference environment. The estimator, applying both the eigenvalues’ statistic characteristics of sample covariance matrix and the noise level of GNSS receiver, is more accurate than the conventional information theoretic criteria with simulation verification. Furthermore, the proposed subspace tracking algorithm outperforms the current frequency detection algorithms in time–frequency domain, such as short-time Fourier transform and smooth pseudo-Wigner-Ville distribution. The theoretical analysis is verified by the real experiments under a GPS L1 scenario.
- Author(s): Ting Cheng ; Shuyi Li ; Jie Zhang
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 1038 –1045
- DOI: 10.1049/iet-rsn.2018.5153
- Type: Article
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1038
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Co-located multiple input multiple output (MIMO) radar is one kind of new style radar, whose transmitting waveforms of each sub-array are orthogonal to each other. Compared with phased array radar, its beam width is wider. Therefore, different targets may be illuminated simultaneously with one beam in co-located MIMO radar. An adaptive resource management in tracking for co-located MIMO radar is proposed, where the sub-array number, the illuminated targets set and the transmitting waveform of the system can be controlled. The optimal parameters are chosen according to a cost function that takes both the desired tracking precision and consumed energy into consideration. Simulation results demonstrate the effectiveness of the algorithm. Using the algorithm, co-located MIMO radar can achieve the desired tracking precision with less cost compared with phased array radar.
- Author(s): Mingyang Wang ; Guolong Cui ; Xiaobo Yang ; Lingjiang Kong
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 1046 –1051
- DOI: 10.1049/iet-rsn.2018.5054
- Type: Article
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This study proposes a new radar-based human body and limb motion recognition method that exploited the temporal sequentiality of the motions. A stacked gated recurrent units network (SGRUN) is adopted to extract the dynamic sequential human motion patterns. Since the time-varying Doppler and micro-Doppler signatures can commendably represent such motion patterns, the spectrogram is utilised as the input sequence of the SGRUN. Numerical experiments verify that an SGRUN with two 34-neuron gated recurrent unit layers well classifies and recognises six distinct human body and limb motion types.
- Author(s): Naglaa El Agroudy ; Mohammed El-Shennawy ; Niko Joram ; Frank Ellinger
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 1052 –1057
- DOI: 10.1049/iet-rsn.2018.5050
- Type: Article
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This study presents a novel frequency modulated continuous wave (FMCW) radar system based on sub-harmonic generation, where a 24 GHz frequency divider-by-10 is used as an active reflector tag. A practical prototype is designed and fabricated on a GF45nm-Silicon on Insulator (SOI) technology for the 24 GHz building blocks, while a GF0.18 µm 7WL Bipolar Complementary Metal Oxide Semiconductor (BiCMOS) technology was used for the 2.4 GHz receiver and baseband. System measurement results show that as opposed to conventional primary radars, the proposed system is immune to strong multi-path interferences resulting from direct reflections of the interrogating signal. The system achieves a ranging precision of 3.7 mm with loop measurements. Moreover, when measured in an indoor environment, the ranging results show a ranging precision and accuracy of 5.8 and 22.3 cm, respectively, which outperform other FMCW radars in the literature.
- Author(s): Jiaxun Tu ; Xingqun Zhan ; Xin Zhang ; Zhenjun Zhang ; Shuai Jing
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 1058 –1065
- DOI: 10.1049/iet-rsn.2018.5151
- Type: Article
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Single-antenna global navigation satellite system (GNSS) spoofing, where all spoofing signals are broadcast by the same antenna, is a great threat to mass market location-based services. This study proposes an anti-spoofing technique based on Doppler frequency difference (DFD) monitoring against single-antenna spoofing, which requires only a standalone receiver with a single antenna. When the receiver moves randomly, the DFD between two authentic satellite signals is non-linear in time domain, whereas between two single-antenna spoofing signals is linear. This study deduces the DFD model and converts the problem of spoofing detection into a sequence linearity detection problem. The hypothesis based on DFD is given, and the statistic is constructed by the method of sequence block processing. This technique has low complexity because it only requires the knowledge of the Doppler frequency without additional information. The detection performance is verified by simulations and real data experiments. The simulation results show that the detection probability can exceed 99.99% easily at 0.001% false alarm probability when the receiver's motion state changes sufficiently. The real data experiments show that the proposed technique can effectively detect GNSS spoofing and distinguish spoofing signals from authentic signals.
- Author(s): Jianhe Lin ; Xiaolei Lv ; Rui Li
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 9, p. 1066 –1076
- DOI: 10.1049/iet-rsn.2018.5053
- Type: Article
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The requirements of the correction of motion errors and high accurate registration are difficult to satisfy for the independence of the aperture paths in airborne repeat-track interferometry. Here, according to the principle of the independence between the imaging scene and synthetic aperture radar (SAR) viewing geometry, the authors propose a new SAR imaging approach based on the idea of object orientation and back-projection (BP), where the complex motion compensation is effectively avoided and the image formation and registration are achieved simultaneously with high accuracy. In contrast to the standard BP algorithm, it greatly reduces the difficulty of registration brought by the irregular deviations. Moreover, it further successfully overcomes the influence introduced by the centre-beam approximation compared with frequency-domain algorithms. Experimental results both on simulated and actual SAR data are used to validate the proposed algorithm.
Radial basis function network-based available measurement classification of interferometric radar altimeter for terrain-aided navigation
Adaptive hybrid method for low-angle target tracking in multipath
Method for InSAR/INS navigation system based on interferogram matching
Linear multitarget integrated probabilistic data association for multiple detection target tracking
Frequency diverse array radar signal and data processing
Velocity estimation of moving targets for spaceborne multichannel synthetic aperture radar systems based on equivalent along-track interferometry technique
First-order ocean surface cross-section for shipborne HFSWR incorporating a horizontal oscillation motion model
Distributed implementation of Kalman object tracker with discrete asynchronous measurements
Fractional sparse energy representation method for ISAR imaging
Distributed target tracking in sensor networks using multi-step consensus
Location reconstructions of attributed SCs by monopulse radar
Comb waveform optimisation with low peak-to-average power ratio via alternating projection
Robust waveform design for MIMO–OFDM-based STAP in the presence of target uncertainty
Interference detection algorithm based on adaptive subspace tracking and RAIM for GNSS receiver
Adaptive resource management in multiple targets tracking for co-located multiple input multiple output radar
Human body and limb motion recognition via stacked gated recurrent units network
Design of a 24 GHz FMCW radar system based on sub-harmonic generation
Low-complexity GNSS anti-spoofing technique based on Doppler frequency difference monitoring
Automatic registered back-projection approach based on object orientation for airborne repeat-track interferometric SAR
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