Online ISSN
1751-8792
Print ISSN
1751-8784
IET Radar, Sonar & Navigation
Volume 5, Issue 2, February 2011
Volumes & issues:
Volume 5, Issue 2
February 2011
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- Author(s): P. Lei ; J. Wang ; J. Sun
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 93 –102
- DOI: 10.1049/iet-rsn.2009.0266
- Type: Article
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p.
93
–102
(10)
Micro-Doppler features have intrinsic relations with the physical properties of objects, which provide great potential for use in the target discrimination. A model and theoretical analysis of micro-Doppler based on inertial parameters for aerospace rigid targets are presented. According to the attitude kinematics in space, mathematical formulas of the micro-Doppler model based on inertial parameters are derived without the limitation of micro-motion types. Moments of inertia and initial rotational angular velocities are used to analyse their impact on micro-motions and micro-Doppler of free rigid targets. After the simulation of radar echoes from objects with various micro-motions, the joint time–frequency analysis is then utilised to demonstrate the time-varying micro-Doppler features and confirm the effectiveness of the model and theoretical analysis. The proposed method highlights the relationship between the model and the attributes of objects and gets rid of the restriction on the specified target shapes, which illustrates more explicit physical meaning and flexibility in the application. - Author(s): F. Nunziata ; M. Migliaccio ; A. Gambardella
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 103 –110
- DOI: 10.1049/iet-rsn.2010.0092
- Type: Article
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p.
103
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In this study fully polarimetric synthetic aperture radar (SAR) measurements are employed for sea oil slick observation. The co-polarised signature is read in terms of sea surface scattering mechanism with and without surface slicks and it is shown to be sensitive to the presence of sea oil slicks. A model, which relates the pedestal of the polarisation signature to the presence of surface slicks, is developed and successfully tested on L-band ALOS-PALSAR, C-band RADARSAT-2 and C-band SIR-C/X-SAR full-polarimetric SAR data. Experiment results show that polarisation signature, and its pedestal height, can be successfully exploited for both observing sea oil slicks and distinguishing them from weak-damping properties look-alikes. - Author(s): B. Gallardo-Hernando ; J.M. Muñoz-Ferreras ; F. Pérez-Martínez ; F. Aguado-Encabo
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 111 –117
- DOI: 10.1049/iet-rsn.2009.0296
- Type: Article
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111
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The use of wind energy is gaining importance because of its many advantages. Nations worldwide are promoting the installation of wind farms to produce electricity in an attempt to tackle climate change and increasing oil costs. However, wind turbines can generate undesired signals that disturb the performance of radar systems. In particular, this is an issue for weather radar networks that see wind turbines as clutter, since they have a strong influence on meteorological outputs such as the estimation of rain intensity or wind velocity. This study develops a simulated scenario and a radar signal model that justify collection of live data from the Spanish Weather Radar Network. Simulated and real data are discussed for both the spotlight and exploration modes. As an application example, a simple algorithm has been developed to estimate wind direction in the immediate vicinity of wind turbines. In this context, it is clear that some meteorological information may be extracted from the wind turbine clutter itself. - Author(s): R. Chen ; Y.F. Cao ; H. Sun
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 118 –127
- DOI: 10.1049/iet-rsn.2009.0294
- Type: Article
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118
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Content-based image retrieval (CBIR) provides an effective way to address the increasing need for intelligent data access to synthetic aperture radar (SAR) image repositories. In CBIR, a critical component is relevance feedback (RF), which is used to bridge the ‘semantic gap’. This study proposes a new RF method with active sample-selecting and manifold learning for CBIR of SAR images. In this method, the authors adopt a modified maximum margin projection with a new neighbourhood estimation criterion to discover both the geometrical structure and discriminant structure of the underlying data manifold. In order to achieve a satisfactory performance with limited feedback samples, the authors also propose an active sample selection strategy with which the diversity of feedback samples can be increased while the redundancy is decreased. The authors test our method on a TerraSAR-X image database and compare it with four other state-of-the-art RF methods. The superiority and validity of the authors’ method is proved by the retrieval results and the computing cost is acceptable for image retrieval applications. - Author(s): W. Liu ; C.R. Zhai ; X.Q. Zhan ; Y.H. Zhang
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 128 –136
- DOI: 10.1049/iet-rsn.2009.0241
- Type: Article
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128
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The increasing number of new global navigation satellite systems (GNSS) signals leads to more interference effects on existing and upcoming navigation signals in the same frequency band. GNSS radio frequency compatibility has become a matter of great concern for the system providers and user communities. This study describes a comprehensive methodology for radio frequency compatibility assessment, and analyses the intersystem interference among several GNSS systems. Firstly, the methodology is presented, considering the geometry-dependent and time-varying terms such as space constellation, signal modulation, emission power level, space loss, satellite antenna gain and user receiver characteristic. Then, the intersystem interference is computed for signals where GPS, Galileo, Compass and SBAS systems are sharing the same frequency band. The analysis results show that interference effects on GNSS user receiver from the above-mentioned systems are acceptable. The introduction of Compass system can provide a sound basis for compatibility with GPS and Galileo. - Author(s): J.Y. Huang ; Q. Wan ; P. Wang
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 137 –143
- DOI: 10.1049/iet-rsn.2010.0061
- Type: Article
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137
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Localisation of mobile station (MS) has now gained considerable attention. It is not possible to further reduce the root mean square error using the existing location methods without additional information. This study proposes a method to improve the accuracy of mobile location using statistical characteristics of MS position as prior information. In this technique, the Chan-Ho method is extended from the maximum likelihood estimator (MLE) to the minimum mean square error estimator (MMSEE). The Cramer-Rao lower bound and theoretical variance of the proposed method are derived. The theoretical proof and simulations show that the proposed MMSEE has the better performance than the MLE. - Author(s): R. Vicen-Bueno ; R. Carrasco-Álvarez ; M.P. Jarabo-Amores ; J.C. Nieto-Borge ; M. Rosa-Zurera
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 144 –154
- DOI: 10.1049/iet-rsn.2010.0001
- Type: Article
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144
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This study presents a novel way for detecting ships in sea clutter. For this purpose, the information contained in the Radar images obtained by an incoherent X-band maritime Radar is used. The ship detection is solved by feedforward artificial neural networks, such as the multilayer perceptrons (MLPs). In a first approach, the MLP processes the information extracted from the Radar images using the commonly used horizontal and vertical selection templates. But, if a suitable combination of these selection templates is done, better detection performances are achieved. So, two improved selection templates are proposed, which are based on cross and plus shapes. All these templates are also applied in a commonly used detector taken as reference, the CA-CFAR detector. Its performance is compared with the one achieved by the proposed detector. This comparison shows how the MLP-based detector outperforms the CA-CFAR detector in all the cases under study. The results are presented in terms of objective (probabilities of false alarm and detection) and subjective estimations of their performances. The improved MLP-based detector also presents low computational cost and high robustness in its performance against changes in the sea conditions and ship properties. - Author(s): D.J. Rabideau
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 155 –162
- DOI: 10.1049/iet-rsn.2010.0034
- Type: Article
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The authors describe a process for designing low-cost, light-weight antenna apertures for use in multiple-input multiple-output (MIMO) radars. In a MIMO radar system, two or more transmitters emit independent waveforms, with the resulting reflections received by an array of receivers. Recently, MIMO radar has become a subject of great interest. In part, this interest is due to the potential for MIMO techniques to reduce radar weight and cost, while maintaining performance (as compared with conventional radar approaches). However, the size of these reductions has not yet been quantified. Here, the authors describe a process for designing optimal radar apertures. This process treats the design problem as one of minimising an objective function under performance constraints. The objective function is based upon a first-order model for the relationship between cost (or weight) and performance, and is derived for systems employing active, element-digitised arrays. A systematic process for optimising the aperture's design with respect to this objective function is presented, and equations describing the optimal aperture are derived. These equations provide insight into the optimal relationship between various aperture characteristics, such as the number of transmitters, number of receivers, module power level and virtual array length. - Author(s): N. Sandirasegaram and C. Liu
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 163 –171
- DOI: 10.1049/iet-rsn.2009.0014
- Type: Article
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In recent years, large numbers of radar images are collected but there is neither time nor enough manpower to go through each collected image. Researchers in the automatic target recognition (ATR) field have developed automated algorithms and tools to analyse each image and obtain higher recognition rate and fewer false alarms but there is still a need for improvement in these aspects. In this study, we have investigated various polarimetric and non-polarimetric techniques and recommended the best ATR approach among those analysed for higher recognition rate and least false alarm rate. The experimental results show that self-organising map (SOM) feature extraction technique with a two-dimensional Fourier transform (2DFFT) algorithm has a better classification rate and a lower false alarm rate. The classifier used here was AND Corporation's holographic neural technology (HNeT) classifier. The SOM technique using |HH|, |HV| and |VV| achieved 98.9% correct classification over the detected targets and reduced the false alarm rate to 8.2%. An ATR system trained with both target and not-a-target class data produced a lower false alarm rate compared with ATR systems trained with target samples alone. This study will help in selection of appropriate methods for future ATR system implementations. In addition, it will assist image analysts (IAs) in choosing appropriate techniques and training datasets to perform their operational tasks. - Author(s): R. Tao ; Y. Feng ; Y. Wang
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 172 –181
- DOI: 10.1049/iet-rsn.2009.0311
- Type: Article
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Classification and identification of moving vessels by extracting particular features of the underwater radiated noise generated by the propellers for use within a port area are an attractive topic for a port underwater surveillance system. The authors first present a chirp-periodic signal model for the envelope of accelerating propeller noise, then derive the maximum-likelihood estimator (MLE) for the evaluation of acceleration and finally propose a novel algorithm for the extraction of acceleration feature on modulated noise (EAFOMN) of the propellers. In addition, a series of experiments were performed for an accelerating propeller in a large cavitation tunnel. The results of the tests show that the actual signal features of accelerating propeller noise is consistent with the presented theoretical analysis, and the proposed algorithm is efficient for passively extracting acceleration of propeller rotation speed. - Author(s): S. Samadi ; M. Çetin ; M.A. Masnadi-Shirazi
- Source: IET Radar, Sonar & Navigation, Volume 5, Issue 2, p. 182 –193
- DOI: 10.1049/iet-rsn.2009.0235
- Type: Article
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p.
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There is increasing interest in using synthetic aperture radar (SAR) images in automated target recognition and decision-making tasks. The success of such tasks depends on how well the reconstructed SAR images exhibit certain features of the underlying scene. Based on the observation that typical underlying scenes usually exhibit sparsity in terms of such features, this paper presents an image formation method that formulates the SAR imaging problem as a sparse signal representation problem. For problems of complex-valued nature, such as SAR, a key challenge is how to choose the dictionary and the representation scheme for effective sparse representation. Since features of the SAR reflectivity magnitude are usually of interest, the approach is designed to sparsely represent the magnitude of the complex-valued scattered field. This turns the image reconstruction problem into a joint optimisation problem over the representation of magnitude and phase of the underlying field reflectivities. The authors develop the mathematical framework for this method and propose an iterative solution for the corresponding joint optimisation problem. The experimental results demonstrate the superiority of this method over previous approaches in terms of both producing high-quality SAR images and exhibiting robustness to uncertain or limited data.
Analysis of radar micro-Doppler signatures from rigid targets in space based on inertial parameters
Pedestal height for sea oil slick observation
Wind turbine clutter observations and theoretical validation for meteorological radar applications
Active sample-selecting and manifold learning-based relevance feedback method for synthetic aperture radar image retrieval
Assessment and analysis of radio frequency compatibility among several global navigation satellite systems
Minimum mean square error estimator for mobile location using time-difference-of-arrival measurements
Ship detection by different data selection templates and multilayer perceptrons from incoherent maritime radar data
Multiple-input multiple-output radar aperture optimisation
Analysis of polarimetric techniques using high-resolution polarimetry data in an automatic target recognition context
Theoretical and experimental study of a signal feature extraction algorithm for measuring propeller acceleration in a port surveillance system
Sparse representation-based synthetic aperture radar imaging
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