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Multiresolution acquisition scheme for the physical layer design of a direct sequence spread spectrum transequatorial HF ionospheric data link

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IET COMMUNICATIONS 2017年第7期11卷 1165-1172页

作者： Alsina-Pages, Rosa Ma Claudi Socoro, Joan Salvador, Marti Hervas, Marcos La Salle Univ Ramon Llull GTM Grp Recerca Tecnol Media C Quatre Camins 30 Barcelona 08022 Spain

This study presents the final implementation of a multiresolution acquisition structure, designed and tested for a long-distance ionospheric High Frequency link from Antarctica to Spain. It completes the receiver's physical layer design for this link of 12,760 km, improving the performance of the communications system. The goals of this proposal are to achieve a faster convergence, as well as a more robust and stable acquisition and demodulation. The multiresolution structure is based on least mean square adaptive filters. Acquisition is achieved when a filter converges to a decimated version of the Pseudo-Noise sequence. Convergence parameters have been adjusted for best performance in the long-haul time variant ionospheric channel. The information about channel's multipath dispersion is used to improve the direct sequence spread spectrum demodulation at the receiver. The results presented in this study are obtained from real data transmitted through the ionospheric Antarctic channel in the austral summer of 2008 and show the improvements in terms of stability, robustness and Bit Error Rate in the receiver. These improvements led us to choose this multiresolution acquisition structure for the receiver of the Antarctic HF system.

关键词： adaptive filters multipath channels long-haul time variant ionospheric channel bit error rate Modulation and coding methods code division multiple access communication system ionospheric Antarctic channel convergence parameters Spain Multiple access communication least mean square adaptive filters filtering methods in signal processing receiver physical layer design channel multipath dispersion least squares approximations radio links demodulation direct sequence spread spectrum demodulation PN sequence multiresolution acquisition scheme Interpolation and function approximation (numerical analysis) BER Radio links and equipment direct sequence spread spectrum transequatorial HF ionospheric data link signal resolution spread spectrum communication multiresolution structure

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Effective statistical-based and dynamic fingerprint preprocessing technique

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IET BIOMETRICS 2017年第1期6卷 9-18页

作者： Iloanusi, Ogechukwu N. Univ Nigeria Dept Elect Engn Fac Engn Nsukka 410001 Enugu State Nigeria

Challenges to contextual filtering techniques include difficulties in estimating orientation field in poor quality images and subsequently failure to extract ridges reliably in large regions of low quality. This study proposes a statistical-based and dynamic fingerprint preprocessing technique for adaptive contrast enhancement and binarisation of fair and poor qualities plain and rolled fingerprints with large regions of low quality, prior to orientation field estimation. The algorithm effectively enhances smudged and faded ridges uniformly in recoverable regions, based on values of statistical variables computed locally in each region. The preprocessing algorithm employs a locally adaptive thresholding approach resulting in enhanced binarised images. The performance of the proposed algorithm was determined by carrying out biometric verification evaluation using a popular commercial biometric matching software, on databases of fingerprints in their original forms, as well as same fingerprints enhanced with the proposed algorithm. Experiments show that fingerprints are uniformly enhanced and binarised;and smudged or faded ridges in recoverable regions made visible. Fingerprint verification evaluation on preprocessed fingerprints resulted in lower error rates in 12 databases. These results show that the proposed algorithm significantly improves recognition.

关键词： locally adaptive thresholding Other topics in statistics fingerprint identification image matching adaptive contrast enhancement biometric verification evaluation Image recognition image segmentation statistical analysis commercial biometric matching software plain fingerprints orientation field estimation contextual filtering techniques dynamic fingerprint preprocessing technique rolled fingerprints statistical-based fingerprint preprocessing technique Computer vision and image processing techniques filtering methods in signal processing image enhancement recoverable regions enhanced binarised images image filtering statistical variables preprocessing algorithm faded ridges smudged ridges

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Non-fragile H_∞ filtering for large-scale power systems with sensor networks

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IET GENERATION TRANSMISSION & DISTRIBUTION 2017年第4期11卷 968-977页

作者： Zhang, Liangliang Zhang, Hongbin Ding, Xuan 2006 Xiyuan AveWi-Hi Tech Zone Chengdu Sichuan Peoples R China Univ Elect Sci & Technol China Sch Elect Engn Chengdu Peoples R China

In this study, the authors investigate the non-fragile H-infinity filtering for large-scale power systems with sensor networks to estimate the state of each subsystem and send the states to different sites. First, for the purpose of enhancing monitoring efficiency, each sensor measures the corresponding subsystem, which can avoid the paralysis of the entire monitoring system caused by the damage of a sensor. Second, they construct the non-fragile filter to adapt the uncertain environment. Sufficient conditions are obtained to ensure that the filtering error system is asymptotically stable with a prescribed H-infinity performance level based on the robust control approach. The filter parameters are determined by solving a set of linear matrix inequalities. A simulation example, which shows the efficiency of the proposed methods is included in this study.

关键词： power system measurement nonfragile H∞ filtering large-scale power systems sufficient conditions Control of electric power systems filtering methods in signal processing Power system management, operation and economics linear matrix inequalities sensor networks uncertain environment Wireless sensor networks filtering error system asymptotic stability monitoring efficiency enhancement filter parameter determination Algebra robust control Power system measurement and metering uncertain systems Stability in control theory Sensing devices and transducers wireless sensor networks H∞ filters power system interconnection

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Geometric barycenters for covariance estimation in compound-Gaussian clutter

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IET RADAR SONAR AND NAVIGATION 2017年第3期11卷 404-409页

作者： Cui, Guolong Li, Na Pallotta, Luca Foglia, Goffredo Kong, Lingjiang Univ Elect Sci & Technol China Sch Elect Engn Chengdu 611731 Peoples R China CNIT Viale GP Usberti181-A I-43124 Parma Italy Udr Univ Federico II Via Claudio 21 I-80125 Naples Italy Elettronica SpA Via Tiburtina Km 13-7 I-00131 Rome Italy

The authors consider the problem of covariance matrix estimation in heterogeneous environments for radar signal processing applications, where the secondary data exhibit heterogeneity in local power and share the same covariance structure. Without resorting to the complete statistical characterisation of the sample support, a class of estimators, each of them defined as the geometric barycenter of a set of basic covariances estimates (obtained from the available secondary data) with a specific distance employed, is proposed. The basic estimates are obtained by exploiting the characteristics of positive-definite matrix space and a condition number upper bound constraint. Finally, they evaluate the detection capabilities of an adaptive normalised matched filter with the proposed estimators in the presence of compound-Gaussian disturbance comparing it with existing alternatives.

关键词： radar signal processing adaptive normalised matched filter compound-Gaussian disturbance condition number upper bound constraint adaptive filters positive-definite matrix space covariance matrix estimation matched filters Algebra Radar equipment, systems and applications geometric barycenters signal detection detection capability covariance matrices filtering methods in signal processing Gaussian processes compound-Gaussian clutter radar clutter radar signal processing applications radar detection statistical characterisation heterogeneous environments Other topics in statistics

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Trajectory estimation for ballistic missile in boost stage using robust filtering

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IET RADAR SONAR AND NAVIGATION 2017年第3期11卷 513-519页

作者： Wang, Xiaogang Qin, Wutao Bai, Yuliang Cui, Naigang Harbin Inst Technol Harbin Peoples R China

This study proposes a new estimation method, referred as the high-degree cubature Huber-based filtering (HCHF). The novel algorithm makes use of the fifth-degree cubature rule to numerically compute Gaussian-weighted integrals, which, with a set of non-linear state equations, are used to compute weighted means and covariance required for measurement update. The measurement update is designed based on the Huber technique which is a combined minimum of l(1) and l(2) norm estimation. Therefore, the HCHF could exhibit robustness when the measurement noise is highly non-Gaussian. The method is applied for tracking ballistic missile in presence of non-Gaussian noise in satellite line-of-sight measurements. The tracking performance is compared with that of extended Kalman filtering and conventional cubature Kalman filtering. The simulation results verified the effectiveness of the proposed non-linear filtering.

关键词： fifth-degree cubature rule measurement update nonlinear equations missiles nonlinear filters satellite line-of-sight measurements Other topics in statistics trajectory estimation l1 norm estimation tracking performance high-degree cubature Huber-based filtering filtering methods in signal processing nonlinear filtering covariance computation Gaussian-weighted integrals boost stage Mathematical analysis Gaussian processes HCHF robust filtering ballistic missile tracking weighted means computation measurement noise nonlinear state equations Military radar, detection and tracking systems nonGaussian noise l2 norm estimation target tracking covariance analysis

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Particle filter-based dual estimation for synchronous generators

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IET GENERATION TRANSMISSION & DISTRIBUTION 2017年第7期11卷 1701-1708页

作者： Cui, Yinan Kavasseri, Rajesh North Dakota State Univ Dept Elect & Comp Engn 1411 Centennial Blvd Fargo ND 58108 USA

This study proposes a particle filter (PF)-based dual estimation method for tracking the dynamic states of a synchronous generator. The authors consider the situation where the field voltage measurements are not readily available. The PF is modified to treat the field voltage as an unknown input which is sequentially estimated along with the other dynamic states. To exploit the tracking results from the estimator, the authors consider the application of use the estimated field voltage to identify internal failures in the excitation subsystem. The proposed method is tested on a 10-machine, 39-bus system to assess selectivity between estimation for regular external disturbances and both physical failure, and modelling abnormality within excitation system. The presented studies show that the proposed method (i) provides reasonable tracking results for the dynamic states and the field voltage simultaneously, (ii) rapidly tracks minor excitation loss due to exciter internal failure while maintaining selectivity and (iii) is robust to measurement noise.

关键词： regular external disturbances 39-bus system particle filter-based dual estimation method state estimation synchronous generators internal failure identification Reliability Synchronous machines excitation system failure analysis filtering methods in signal processing excitation subsystem measurement noise minor excitation loss tracking particle filtering (numerical methods) PF-based dual estimation method abnormality modelling

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Robust algorithm for multiview registration

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IET COMPUTER VISION 2017年第1期11卷 96-103页

作者： Pankaj, Dhanya S. Nidamanuri, Rama Rao Indian Inst Space Sci & Technol Dept Earth & Space Sci Thiruvananthapuram Kerala India

Multiview registration is an important stage in three-dimensional modelling pipeline. Motion averaging is an efficient approach for multiview registration which utilises the redundancy in overlap among the scans. The averaging of the underlying relative motions is performed in the corresponding Lie-algebra elements of the SE(3) transformation matrices. However, this method is non-robust and affected by the presence of outliers in the set of relative motions. The authors present a graph-based approach to filter out the outliers before performing averaging of motions. The relative motions are assigned weights based on their agreement with global motions and other relative motions. The results indicate that the authors' approach can efficiently filter out the outliers and can thus introduce robustness to multiview registration using motion averaging.

关键词： image registration outlier filtering Combinatorial mathematics three-dimensional modelling pipeline image scan redundancy graph-based approach matrix algebra SE(3) transformation matrices graph theory motion averaging Algebra Optical, image and video signal processing Computer vision and image processing techniques filtering methods in signal processing image motion analysis image filtering lie-algebra element overlap redundancy multiview registration robust algorithm

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Tracking with MIMO sonar systems: applications to harbour surveillance

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IET RADAR SONAR AND NAVIGATION 2017年第4期11卷 629-639页

作者： Pailhas, Yan Houssineau, Jeremie Petillot, Yvan Rene Clark, Daniel Edward Heriot Watt Univ Sch Engn & Phys Sci Edinburgh Midlothian Scotland

Multiple-input multiple-output (MIMO) sonar systems offer new perspectives for area surveillance especially in complex environments where strong multipath and dense clutter can become very challenging. This study proposes a MIMO sonar system based scheme to tackle the difficult problem of harbour surveillance. An emphasis is put on recognition and tracking on low-profile mid-water targets. First, a MIMO simulator which can compute synthetic raw data for any transmitter/receiver pair in a multipath, cluttered and dynamic environment is presented. The study then proposes two radically different methods for the underwater target tracking problem in complex environment: a digital tracker and an analogue tracker. On the digital side, an implementation of the recently developed hypothesised filter for independent stochastic populations is presented. This filter enables robust multi-object tracking as well as track classification capabilities without the use of heuristics. An analogue filter based on acoustical time reversal techniques is also introduced. This filter directly uses the returned acoustic field from the scene to focus the sound on the expected target position, hence improving the signal-to-noise ratio on the target in complex environments and taking full advantage of the MIMO architecture.

关键词： sonar tracking surveillance strong multipath clutter signal-to-noise ratio underwater target tracking problem digital tracker multiple-input multiple-output sonar systems classification capability tracking analogue tracker MIMO simulator clutter low-profile mid-water target recognition low-profile mid-water target tracking MIMO sonar systems independent stochastic populations sonar target recognition acoustical time reversal techniques Sonar and acoustic radar filtering methods in signal processing autonomous underwater vehicles tracking filters hypothesised filter acoustic field dense clutter transmitter-receiver pair tracking filter harbour surveillance analogue filter target tracking object tracking signal classification robust multiobject tracking

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Integrated particle smoothing for target tracking in clutter

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IET RADAR SONAR AND NAVIGATION 2017年第4期11卷 551-562页

作者： Shi, Yi Fang Chong, Sa Yong Song, Taek Lyul Hanyang Univ Dept Elect Syst Engn Ansan South Korea

The integrated particle filter (IPF) is an algorithm for single-target tracking in clutter, which incorporates the probability of target existence (PTE) into the traditional particle filter as a track quality measure for false track discrimination (FTD). This study investigates two IPF-based fixed-interval smoothing algorithms: the IP smoothing (IPS) algorithm and the IP-Rauch-Tung- Striebel backward smoothing (IP-RTSBS) algorithm, both of which are capable of trajectory estimation and FTD. The IPS algorithm fuses the propagations for each pair of forward IPF and backward IPF particles to obtain the smoothing propagation that is used to update the track state by applying all available measurements in the current scan. The IP-RTSBS algorithm employs the forward filtering backward smoothing approach to smooth the trajectory state, which is then applied to the RTS smoothing methodology to obtain the smoothing propagation used to update the PTE. As a result, both FTD and trajectory estimation are improved. The smoothing benefits of the two algorithms are validated in the simulations, where a sliding batch mode with overlapping measurements is utilised to limit the smoothing lag.

关键词： single-target tracking Electromagnetic compatibility and interference IP-RTSBS algorithm track quality measure FTD IPS algorithm clutter Digital signal processing integrated particle filter probability-of-target existence false track discrimination sliding batch mode trajectory estimation particle filtering (numerical methods) IP-Rauch-Tung-Striebel backward smoothing algorithm integrated particle smoothing filtering methods in signal processing IP smoothing algorithm smoothing propagation IPF-based fixed-interval smoothing algorithms signal processing theory smoothing methods forward filtering backward smoothing approach electromagnetic wave propagation Electromagnetic wave propagation target tracking Monte Carlo methods RTS smoothing methodology

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Robustness versus accuracy: multipath effects on land mobile satellite navigation

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IET RADAR SONAR AND NAVIGATION 2017年第3期11卷 520-527页

作者： Steingass, Alexander Krach, Bernhard Crisci, Massimo German Aerosp Ctr DLR Inst Commun & Nav Muenchnerstr 20 D-82234 Wessling Germany European Space Agcy Radio Nav Syst & Tech Sect Keplerlaan 1 NL-2200 AG Noordwijk Netherlands

Knowledge of performance for different signal options in difficult environments is vital for improving modern satellite navigation systems. Currently, the accuracy of the different transmission signals in realistic multipath environments is still not known in current literature. In this study, different classical and advanced signals have been simulated using an urban multipath channel model standardised by the International Telecommunication Union. For the given multipath channel, signal and receiver effects have been investigated. The performance of GPS C/A and GALILEO open service signals has been compared. Additional simulation of wideband navigation signals lead to the uncovering of an important conflict between robustness and accuracy in terms of signal bandwidth. This conflict is signal inherent and not associated to a particular receiver. As a result of this finding, an improved satellite signal extension for robust urban navigation has been proposed. On the receiver side, pure line-of-sight (LOS) conditions have been identified in which a novel particle filter-based receiver shows a comparable performance as a classical delay locked loop (DLL). In a mixture of LOS and shadowing conditions the particle receiver clearly outperformed the classical DLL. For the classical DLL, critical scenarios have been identified that are often causing a loss of lock.

关键词： transmission signal shadowing condition Satellite communication systems mobile satellite communication classical delay locked loop multipath channels particle filter-based receiver line-of-sight condition multipath environment Mobile radio systems classical DLL wireless channels GPS C-A open service signal performance particle receiver particle filtering (numerical methods) LOS condition filtering methods in signal processing radio receivers land mobile radio land mobile satellite navigation GALILEO open service signal performance receiver effects Global Positioning System International Telecommunication Union multipath effects modern satellite navigation system improvement wideband navigation signal simulation signal effects urban multipath channel model

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