IET Radar, Sonar & Navigation
Volume 12, Issue 2, February 2018
Volumes & issues:
Volume 12, Issue 2
February 2018
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- Author(s): Sophie Jordan ; Julian Moore ; Sierra Hovet ; John Box ; Jason Perry ; Kevin Kirsche ; Dexter Lewis ; Zion Tsz Ho Tse
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 151 –164
- DOI: 10.1049/iet-rsn.2017.0251
- Type: Article
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Visual condition inspections serve as the basis for determining the need and schedule for service tasks such as maintenance and remediation projects to preserve the proper functioning of power facilities and infrastructure. An increasing accumulation of service projects has recently surfaced due to the lengthy, labour-intensive and subjective qualities of the current method for inspection. These processes are also costly due to the temporary closure of the infrastructure as well as the requirement of special inspection equipment. Unmanned aerial vehicles (UAVs), commonly known as drones, offer potential as a useful tool for infrastructure inspections. UAVs provide visual assessments of structures while eliminating the need for manual inspections. Thus, aerial systems have the potential to reduce the cost of inspections as well as limit the disruption of the public while allowing engineers to have a better three-dimensional understanding of the system. However, the implementation of UAV inspection includes several difficulties such as flight stability, control accuracy, and safety. This study summarises the context for UAV inspection of power facilities and structures. Technologies to address the hindrances preventing UAV integration into the current practice are reviewed. Existing challenges and future work in research for UAV inspections are also presented.
- Author(s): Abdul Basit ; Wasim Khan ; Shafqatullah Khan ; Ijaz Mansoor Qureshi
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 165 –175
- DOI: 10.1049/iet-rsn.2017.0207
- Type: Article
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Electronic beam steering with greater efficiency is a vibrant feature of a phased array antenna, but for all the range cells, it is fixed at a specific angle. To mitigate this problem, frequency diverse array (FDA) antenna was proposed. This study presents a review on the development of FDA technology in radar and navigation applications. FDA is different from a conventional phased array antenna radar in a sense that it uses a small frequency offset across the array, which helps to generate a range, angle and time-dependent beam pattern. This pattern assures the energy transmission towards the desired angle and range cell. In addition, this study also focuses the research on getting range-angle uncoupled beam patterns along with diverse hybrid cognitive FDA design, available in the literature, for improved radar performance.
State-of-the-art technologies for UAV inspections
Development of frequency diverse array radar technology: a review
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- Author(s): Amar Mezache ; Amel Gouri ; Houcine Oudira
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 176 –185
- DOI: 10.1049/iet-rsn.2017.0234
- Type: Article
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Compound Gaussian inverse Gaussian (CGIG) distribution with thermal noise is well suited for sea clutter. The compact expression of higher order moments estimator (HOME) for CGIG clutter plus noise parameters is derived. When non-integer order moments (NIOM) are considered, numerical integration based on ‘Legendre’ and ‘Laguerre’ polynomials of Gauss quadrature method is employed. This estimator is referred to as constrained NIOM estimator (NIOME)-based method. Using the two first intensity moments, a constrained maximum likelihood estimator (CMLE) is formed by minimising the negative log likelihood function in one variable to obtain the shape parameter. For comparison purposes, computer simulations are presented with known and unknown clutter-to-noise ratio (CNR). In the case of known CNR, the method of moments provides a good fit as well as the NIOME and the CMLE methods. For unknown CNR, regardless the computing time, the HOME method is less accurate than the others. The constrained NIOME method requires numerical optimisation with acceptable calculation time. In most cases, the CMLE approach is accurate, but relatively slow due to the calculation of numerical integration of likelihood functions.
- Author(s): Mohammad Ali Alirezapouri ; Hamid Khaloozadeh ; Ahmadreza Vali ; Mohammad Reza Arvan
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 186 –194
- DOI: 10.1049/iet-rsn.2017.0293
- Type: Article
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The stochastic models developed for the manoeuvring target tracking (MTT) problem do not exhibit good performance owing to the lack of sufficient information about uncertainties. Moreover, each of the MTT models can be used for limited target manoeuvres. An ‘unknown but bounded’ (UBB)-based non-linear dynamic model for modelling time-dependent acceleration and model uncertainties is proposed for addressing the aforementioned problems. In the UBB approach, uncertainties and target manoeuvre are modelled using information about their upper bounds only. The extended set membership filter can be used to estimate the target states and manoeuvre with this new dynamic model. In order to examine the stability of the proposed method, the input to state stability of the estimation error is analysed. Very good performance is achieved by the proposed dynamic model without precise information about the model uncertainties. The proposed MTT algorithm can be used to track both non-manoeuvring and manoeuvring targets. The theoretical development is verified using simulations and the results are compared with those of other MTT methods. These comparisons demonstrate that the performance of the proposed method is better.
- Author(s): Eduardo Santos and Simon Haykin
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 195 –201
- DOI: 10.1049/iet-rsn.2017.0162
- Type: Article
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A modified version of the probabilistic data association (PDA) is proposed for target tracking under measurement uncertainty conditions. This method uses the likelihood of each validated measurement, and selects the best k candidates to be integrated with the PDA. Different computer simulations with a single target under dense-cluttered environment are presented. Comparison to the standard PDA shows a track loss reduction with the proposed method.
- Author(s): Peng-Lang Shui ; Han Yu ; Li-Xiang Shi ; Chun-Jiao Yang
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 202 –208
- DOI: 10.1049/iet-rsn.2017.0174
- Type: Article
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Compound-Gaussian model with inverse Gamma distributed texture is a powerful tool to characterise heavy-tailed sea clutter. The parameters of the model need to be estimated in advance or online to assist the optimum detection. Moment-based estimators are suitable for a limited range of shape parameter, the maximum likelihood (ML) estimator lacks an explicit expression and fast iterative solution, and the method of log-cumulants (MoLC) can work in all cases but is not good for large shape parameters. Moreover, their performance is sensitive to outliers in samples. Explicit bipercentile estimators are proposed to estimate the scale and shape parameters, which are computationally efficient and outliers robust. Without outliers in samples, the bipercentile estimators are comparable with the moment-based estimators and MoLC estimator in performance except when the number of samples is very small. With outliers in samples, the bipercentile estimators are much better than the moment-based and ML estimators. Moreover, the ability of the bipercentile estimators is verified by measured sea clutter data.
- Author(s): Feiya Zhu ; Yunhua Zhang ; Dong Li
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 209 –217
- DOI: 10.1049/iet-rsn.2017.0158
- Type: Article
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Information loss and proliferation of parameters (PoP) in polarimetric synthetic aperture radar (PolSAR) eigenvalue/eigenvector-based target decomposition had not been well treated until Paladini et al. recently devised a lossless and sufficient decomposition of the coherency matrix under circular polarisation basis, and a classification scheme based on the decomposed parameters was also proposed to validate the decomposed parameters. Inspired by the Paladini incoherent target decomposition, a new lossless and sufficient eigenvalue/eigenvector-based decomposition of the coherency matrix under Pauli basis is proposed. Compared to the coherency matrix under circular basis, the coherency matrix under Pauli basis is more frequently used because it is more convenient for interpreting the polarimetric scattering mechanism. The proposed decomposition not only deals with these two problems (information loss and PoP) well but also avoids the possible ambiguity of the α angle of the Paladini decomposition. In addition, both the two decompositions are serial or multiplicative decomposition, while other common target decompositions are parallel or additive decompositions. A further modified fine classification scheme is carried out to validate the decomposed parameters. Real PolSAR data are processed to validate the proposed decomposition.
- Author(s): Wenxiu Chang ; Jingpei Ru ; Lifei Deng
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 218 –226
- DOI: 10.1049/iet-rsn.2017.0187
- Type: Article
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In this study, the problem of Stokes parameters and direction-of-arrival estimation of polarised sources is addressed based on the block-sparsity reconstruction, in case of an unknown number of sources. Since Stokes parameters have four components, the block-sparsity model of polarised sources is introduced by employing the difference coarray of the coprime array with cross-dipole sensors. In case of an unknown number of sources, a novel estimate approach is proposed by combining the block orthogonal matching pursuit (BOMP) algorithm with the deterministic maximum likelihood (DML). In the proposed approach, the DML test step and refining grid step are added in each iteration of BOMP to identify the number of sources and to reduce the estimation error incurred by the grid mismatch. This approach has low computational complexity and is suitable for both the completely polarised and partially polarised sources. Simulations are used to verify the performance of the proposed approach.
- Author(s): Leilei Xu ; Shenghua Zhou ; Hongwei Liu ; Huikai Zang ; Lin Ma
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 227 –238
- DOI: 10.1049/iet-rsn.2017.0340
- Type: Article
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Distributed multiple-input–multiple-output radar usually needs to transmit nearly orthogonal waveforms, but the constant-modulus requirement from engineering applications often makes sidelobe levels difficult to suppress. In this study, the authors resort to two approaches to further suppress the sidelobe levels, i.e. orthogonal phase-coded waveforms with expanded mainlobe (OPCWEM) and its mismatched filters design. Specifically, they first propose a minimisation criterion to design nearly OPCWEM, which is a non-convex optimisation problem and solved by a least-pth minimax algorithm. Next, they design mismatched filters with given OPCWEM, which is formulated as a convex optimisation problem with min–max criterion and solved by a convex optimisation algorithm. Numerical results validate the effectiveness of the two approaches and the Doppler sensitivity is also analysed.
- Author(s): Juan Wang ; Tong Wang ; Jianxin Wu
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 239 –243
- DOI: 10.1049/iet-rsn.2017.0294
- Type: Article
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In order to avoid straddling loss, airborne phased array scanning radar transmits beams with small step angle, and then the same target can be detected again and again in multiple adjacent beams through azimuth scanning. Therefore, considering its long-range surveillance and high revisit rate, the authors may assume that the azimuth angle of the same target almost keeps unchanged during multiple beams. Furthermore, they can also model the target complex amplitude from each beam as an unknown deterministic signal with amplitude and phase difference that accounts for the antenna pattern and sampling starting time. A direction-of-arrival estimation algorithm that utilises multiple beams to obtain an accurate target angle is proposed. The signal model that jointly considers received data from multiple adjacent beams is introduced, and the maximum likelihood (ML) estimation of target angle in noise and jamming sceneries is obtained. The performance of proposed method is investigated through Monte-Carlo simulations and compared with both the Cramer–Rao lower bound and with conventional ML technique that utilises one beam. Simulation results validate the effectiveness of the presented algorithm.
- Author(s): Juan Zhang ; Yong Li ; Junping Yin
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 244 –249
- DOI: 10.1049/iet-rsn.2017.0265
- Type: Article
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Signal modulation classification is an important research subject in both military and civilian field. This study proposed a novel blind modulation classification method based on the time–frequency distribution and convolutional neural network (CNN). This is the first attempt to treat the time–frequency map as a picture and use an outstanding (CNN-based) algorithm in computer vision area for signal recognition. The combination offers a novel feature extraction strategy, to some extent, which also conforms to intuition. Simulation results show that the method proposed in this study is efficient and robust and enables a high degree of automation for extracting features, training weights and making decisions. Additionally, a remarkable performance emerges with small samples and repeated training, which distinguishes this method from many other classification methods.
- Author(s): Mohammad Samizadeh Nikoo and Fereidoon Behnia
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 250 –259
- DOI: 10.1049/iet-rsn.2017.0348
- Type: Article
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Passive localisation of non-cooperative targets through their electromagnetic emissions is an attractive issue. This localisation task can be carried out using multitude of receiver sites being linked together. This multiplicity, however, brings about difficulties in organising and coordinating the sites. One can even claim that the method is no longer passive considering the necessary communication links between the sites. On the other hand, single-site localisation methods basically overcome these difficulties eliminating the need for inter-site communications. In this study, a single-site localisation method is presented and analysed. This method is applicable to scenarios with a large known object which plays the role of an electromagnetic wave scatterer. The single receiver site receives both direct and scattered waves through two different antenna systems and analyses them to localise the target. Electromagnetic simulation using the finite-difference time-domain method was applied to the problem showing good agreement with the theoretical results. The present study also investigates the effects of noise on the accuracy of localisation. Some of the important practical considerations of the method, like the electromagnetic modelling of the dominant scatterer, are also discussed.
- Author(s): Xinglin Shen ; Zhiyong Song ; Hongqi Fan ; Qiang Fu
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 260 –267
- DOI: 10.1049/iet-rsn.2017.0201
- Type: Article
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When a target generates multiple detections, standard tracking algorithms are not applicable. Unlike extended target tracking, which has received considerable attention, studies on generalised multiple-detection tracking (MDT) are still scarce. MDT algorithms proposed in recent years suffer from high computational complexity. In this work, based on distance partitioning, the authors propose a generalised distance partitioning (GD partitioning) algorithm to reduce the number of partitions, and thus decrease the computational complexity of MDT filters. In the algorithm, after defining a multi-detection distance and calculating the corresponding distance threshold, the authors calculate the original partition of measurement set by using distance partitioning. Subsequently, on the basis of original partition, they can obtain informative subsets to replace all subsets in a multiple-detection Bernoulli filter, as well as a collection of partitions to replace all partitions in multiple-detection probability hypothesis density filter. Simulations show that the algorithm can notably reduce the number of subsets and partitions. Thus, by means of a partitioning algorithm, computational complexity of random finite set-based MDT filters is decreased successfully, which implies that a GD partitioning algorithm may play an important part in real-time MDT systems.
- Author(s): Mohammad T. Alkhodary and Ali H. Muqaibel
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 268 –275
- DOI: 10.1049/iet-rsn.2017.0143
- Type: Article
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Ultra-wideband (UWB) radar imaging can provide high-resolution images of obscured objects using radio-frequency signals. Due to its vast applications, UWB radar imaging received considerable attention in the past decade. Compressive sensing (CS) has been used as a viable solution for the larger data required by radar imaging. The advances of CS-based UWB-radar imaging is burdened by the complexity of the reconstruction algorithms and their weak noise immunity. Exploiting the structure of the basis-matrix, a low-complexity Bayesian-based estimation algorithm is proposed. The algorithm takes advantage of the radar-return statistic to find an approximate minimum mean-square error estimate of the radar image. The low complexity is achieved by utilising the block-matrix-inversion formula to execute the algorithm in an order-recursive manner. Further simplification is achieved by using exponential-sum formula to find the correlation between the columns of the basis-matrix. The proposed algorithm is evaluated over experimental and simulated data. The results show faster processing time compared to other known algorithms, with comparable reconstruction quality.
- Author(s): Rameez Ahmed Malik ; Mohammad Yousaf Khan ; Ghulam Jaffer ; Nazish Rubab
- Source: IET Radar, Sonar & Navigation, Volume 12, Issue 2, p. 276 –285
- DOI: 10.1049/iet-rsn.2017.0318
- Type: Article
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Current navigation satellite systems (Global Positioning System (GPS), GLObal'naya NAvigatsionnaya Sputnikovaya Sistema (GLONASS) and BeiDou-2) have enabled quality of life improvements on a global scale. The applications include in the fields of transportation, military, aviation and security etc. Annual business market value of Global Navigation Satellite System user equipment and related components has been estimated at billions of US dollars. To reap the benefits maximally, various countries are developing their Regional Navigation Satellite Systems (RNSSs). Independent RNSS guarantees uninterrupted and reliable services with an advantage of the customised coverage. This study presents the design of two constellation models, including a Highly Elliptical Orbit/Geostationary Orbit (HEO/GEO) and a Geostationary Orbit/Inclined Geosynchronous (GEO/IGS) constellation for Pakistan's regional navigation system. The performance analysis of the navigation ability of designed constellations is carried out by analysing various parameters such as number of satellites, Dilution of Precision and navigation accuracy in a constrained environment and comparing these parameters with the GPS using dynamic simulations. Navigation link budget of both constellations is theoretically calculated, verified and compared with that of the GPS. Parametric analysis proposes that HEO/GEO and GEO/IGS orbit-based constellations can be adopted as replacement of the GPS for independent navigation within Pakistan.
Parameter estimation of CGIG clutter plus noise using constrained NIOME and MLE approaches
Set value-based dynamic model development for non-linear manoeuvring target tracking problem in the presence of unknown but bounded disturbances
Data association for target tracking rooted in maximum-likelihood values
Explicit bipercentile parameter estimation of compound-Gaussian clutter with inverse gamma distributed texture
Eigenvalue/eigenvector-based serial decomposition of the polarimetric synthetic aperture radar coherency matrix
Stokes parameters and DOA estimation of polarised sources with unknown number of sources
Distributed multiple-input–multiple-output radar waveform and mismatched filter design with expanded mainlobe
Improved target direction-of-arrival estimation using multiple adjacent beams for airborne phased array scanning radar
Modulation classification method for frequency modulation signals based on the time–frequency distribution and CNN
Single-site source localisation using scattering data
Generalised distance partitioning for multiple-detection tracking filter based on random finite set
Low complexity sparse Bayesian estimation for UWB radar imaging
Cost-effective and novel regional navigation system using HEO/GEO and GEO/IGS Constellations
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