1,721,244 research outputs found
Integrated MIMO Passive Radar Target Detection
No full textIntegrated passive radar (IPR) can be regarded as next-generation passive radar technology, which aims to integrate communication and radar systems. Unlike conventional passive radar, which does not prioritize communication-centric radar technology, IPR technology places a higher priority on incorporating specific radar constraints to develop waveforms that are better suited for radar applications. This paper deals with the problem of distributed MIMO IPR target detection under uncalibrated surveillance/reference receivers. We focus on a communication-centric radar system consisting of several opportunity transmitters non-overlapping in frequency with the same bandwidth and several spatially separated receivers. Five new detectors are devised according to the likelihood ratio test (LRT), Rao, Wald, Gradient, and Durbin criteria. Although it is shown that these detectors are asymptotically equivalent, they provide different performances in the presence of noisy reference channels. The invariance principle is applied in this paper to show that all uncertainties affecting threshold setting can be unified in the direct-path signal power-to-noise power ratio (DNR) of the reference channels. To ensure effective detection threshold setting regardless of the DNR values in the reference channels, we introduce a novel strategy to adjust the level of the proposed detectors rather than their sizes. Then, we examine false alarm regulations and the detection performance of the fixed-level proposed detectors to demonstrate their effectiveness compared to several existing detectors. Thus, we create a unified framework for uncalibrated MIMO IPR target detection in the presence of noisy reference channels
GamiDOC: The Importance of Designing Gamification in a Proper Way
No full textGamification, commonly described as the use of game design elements in non-game contexts, is frequently adopted to enhance users' motivation, engagement, and happiness while supporting them in reaching different objectives, related to learning activities and behavioral changes. Despite being a widely used approach, several studies show that the final outcomes following gamification use are not always positive. To face this problem, we developed a tool called GamiDOC composed of different features aimed at facing the existing problems in the gameful systems design process and, at the same time, guiding designers and practitioners in the design and evaluation of gamified solutions. In this paper, we present the elements that make gameful systems design a challenging process, the state of the art in gamification design, and the issues that are still open in the design of gameful systems. Finally, we provide a detailed description of GamiDOC and why the tool stands as a valuable solution to guide users across all the stages of gameful systems design, development, and evaluation. Finally, we present a usability evaluation of GamiDOC and a use-case scenario
Performance comparison of mean-level CFAR detectors in homogeneous and non-homogeneous Weibull clutter for MIMO radars
Full text linkIn this paper, we analyze and compare the performance of the CA-CFAR, GO-CFAR and the SO-CFAR detectors in homogeneous and non-homogeneous Weibull background with known shape parameter for Multi-Input Multi-Output radars with widely separated antennas. The non-homogeneity is represented by the presence of interfering targets and a clutter edge in the reference window. We derive closed-form expressions of the probability of false alarm of the three detectors in homogeneous environment. Detector performance in non-homogeneous environment is investigated by means of Monte Carlo simulations. The numerical results show that the best performance is obtained by the SO-CFAR in the case of a high number of interferences, whereas the GO-CFAR has the best false-alarm regulation when the number of cells contaminated by clutter exceeds half the number of reference cells
Distributed MIMO Passive Radar Target Detection: Holy Trinity, Durbin, and Gradient Tests
No full textThis paper addresses the problem of target detection in a two-channel distributed MIMO passive radar (PR). In this scenario, multiple distributed transmitters emit signals that are received by the two-channel distributed receivers, one channel for surveillance and the other for reference. Both receiver channels are utilized to formulate the target detection problem as a binary composite hypothesis testing issue. To tackle this, we develop five detectors based on the generalized likelihood ratio test (GLRT), Rao, Wald, Gradient, and Durbin criteria. This framework for two-channel distributed MIMO PR target detection takes into account noisy reference channels. The invariance principle is employed here to show that all uncertainties affecting threshold setting can be consolidated into the direct-path signal power-to-noise ratio (DNR) in the reference channels. We also introduce the concept of “level-of-test,” which allows us to effectively adjust the detection thresholds irrespective of the DNR values of the reference channels. Among the proposed detectors, the Rao-based test exhibits superior and robust performance. Furthermore, the results demonstrate that the proposed detectors outperform the existing alternatives
Cross-Channel Interference in Multi-User Radar Systems
No full textIn this paper we evaluate the impact of the presence of interfering radar on the target direction of arrival (DOA) monopulse estimation performed by the reference radar. The importance of the use of codes in multi-user radar system is highlighted in a simple scenario of two cooperating radars. © 2007 IEEE
Semiparametric stochastic CRB for DOA estimation in elliptical data model
No full textThis paper aims at presenting a numerical investigation of the statistical efficiency of the MUSIC (with different covariance matrix estimates) and the IAA-APES Direction of Arrivals (DOAs) estimation algorithms under a general Complex Elliptically Symmetric (CES) distributed measurement model. Specifically, the density generator of the CES-distributed data snapshots is considered as an additional, infinite-dimensional, nuisance parameter. To assess the efficiency in the considered semiparametric setting, the Semiparametric Stochastic Cramér-Rao Bound (SSCRB) is adopted as lower bound for the Mean Square Error (MSE) of the DOA estimators
Non-stationarity analysis of real X-Band clutter data at different resolutions
No full textThis work deals with the problem of providing a statistical model of the backscattering from marine surface for low-grazing angle and high resolution radar systems. Based on the electromagnetic two-scale model, we analyzed both the amplitude and frequency modulations induced on the small-scale Bragg resonant waves by the large-scale surface tilt and advection, due to the swell presence. Evidence of marine clutter non-stationarity and the relationship between the variations of clutter texture, Doppler centroid and bandwidth have been investigated by processing measured data, recorded by the IPIX radar of McMaster University in Grimsby, Ontario, Canada. Our results demonstrate that sea/lake clutter at different range resolutions is non-stationary and is better modeled by a hybrid AM/FM modulated process. © 2006 IEEE
Radar detection and preclassification based on multiple hypothesis
No full textThis work presents a single-scan-processing approach to the problem of detecting and preclassifying a radar target that may belong to different target classes. The proposed method is based on a hybrid of the maximum a posteriori (MAP) and Neyman-Pearson (NP) criteria and guarantees the desired constant false alarm rate (CFAR) behavior. The targets are modeled as subspace random signals having zero mean and given covariance matrix. Different target classes are discriminated based on their different signal subspaces, which are specified by their corresponding projection matrices. Performance is investigated by means of numerical analysis and Monte Carlo simulation in terms of probability of false alarm, detection and classification; the extra signal-to-noise power ratio (SNR) necessary to classify once target detection has occurred is also derived. © 2004 IEEE
GamiDOC: The Importance of Designing Gamification in a Proper Way
No full textGamification, commonly described as the use of game design elements in non-game contexts, is frequently adopted to enhance users' motivation, engagement, and happiness while supporting them in reaching different objectives, related to learning activities and behavioral changes. Despite being a widely used approach, several studies show that the final outcomes following gamification use are not always positive. To face this problem, we developed a tool called GamiDOC composed of different features aimed at facing the existing problems in the gameful systems design process and, at the same time, guiding designers and practitioners in the design and evaluation of gamified solutions. In this paper, we present the elements that make gameful systems design a challenging process, the state of the art in gamification design, and the issues that are still open in the design of gameful systems. Finally, we provide a detailed description of GamiDOC and why the tool stands as a valuable solution to guide users across all the stages of gameful systems design, development, and evaluation. Finally, we present a usability evaluation of GamiDOC and a use-case scenario
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