In this paper we investigate and study the performance of a high resolution cell-average constant false alarm rate (CA-CFAR) radar of a Swerling II target embedded in sea clutter plus additive Gaussian thermal noise. The sea clutter is... more
In this paper we investigate and study the performance of a high resolution cell-average constant false alarm rate (CA-CFAR) radar of a Swerling II target embedded in sea clutter plus additive Gaussian thermal noise. The sea clutter is modelled as NG-distribution. Closed form expressions for probabilities of false alarm and detection are derived. Also, Monte Carlo simulations are carried out to assess the system performance both theoretically and by simulations. (4 pages)
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This paper is a contribution for the suppression of interferences in monostatic airborne radar detection. We propose to consider the projection approximation subspace tracking (PAST) and orthonormal PAST (OPAST) algorithms for the... more
This paper is a contribution for the suppression of interferences in monostatic airborne radar detection. We propose to consider the projection approximation subspace tracking (PAST) and orthonormal PAST (OPAST) algorithms for the reduction of the rank. Simulation results are presented and the performance of space-time adaptive processing (STAP) is discussed with a comparative study to the principal components (PC) method. Performance curves show that PAST and OPAST do indeed allow good detection of slow moving targets even with low rank covariance matrix. In order to achieve good detection performance in the case of Doppler ambiguous environment, we propose a novel idea using the rich properties of chaos. It resides in changing the PRF in a chaotic manner. Results show that this solves well the problem of ambiguities while using a reduced rank STAP. Furthermore, we also show using a chaotic staggered PRF, the recursive algorithms give better results than the methods based on eigenv...
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... Reference Selected Bibliography 532 532 Chapter 10 Detection and Parameter Estimation 533 10.1 Introduction 533 Binary Detection 534 10.2.1 Simple Binary Detection 534 10.2.2 General Binary Detection 543 M-ary Detection 556 10.3.1... more
... Reference Selected Bibliography 532 532 Chapter 10 Detection and Parameter Estimation 533 10.1 Introduction 533 Binary Detection 534 10.2.1 Simple Binary Detection 534 10.2.2 General Binary Detection 543 M-ary Detection 556 10.3.1 Correlation Receiver 557 10.3.2 ...
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: In radar signal detection, the problem is to automatically detect a target in a nonstationary noise and clutter background while maintaining a constant probability of false-alarm. Classical detection using a matched filter receiver and... more
: In radar signal detection, the problem is to automatically detect a target in a nonstationary noise and clutter background while maintaining a constant probability of false-alarm. Classical detection using a matched filter receiver and a fixed threshold is not applicable due to the nonstationary nature of the background noise. Therefore, adaptive threshold techniques are needed to maintain a constant false-alarm rate(CFAR). One approach to adaptive detection in nonstationary noise and clutter background is to compare the processed target signal to an adaptive threshold. In the cell-averaging CFAR processing, an estimate of the background noise from the leading and the lagging reference windows is used to set the adaptive threshold. A threshold multiplier(or scaling factor)is used to scale the threshold to achieve the desired probability of false-alarm. In the first part of this report, we have proposed two modified cell-averaging detectors for multiple target situations. The first...
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: In radar signal detection, the problem is to automatically detect a target in a nonstationary noise and clutter background while maintaining a constant probability of false-alarm. Classical detection using a matched filter receiver and... more
: In radar signal detection, the problem is to automatically detect a target in a nonstationary noise and clutter background while maintaining a constant probability of false-alarm. Classical detection using a matched filter receiver and a fixed threshold is not applicable due to the nonstationary nature of the background noise. Therefore, adaptive threshold techniques are needed to maintain a constant false-alarm rate(CFAR). One approach to adaptive detection in nonstationary noise and clutter background is to compare the processed target signal to an adaptive threshold. In the cell-averaging CFAR processing, an estimate of the background noise from the leading and the lagging reference windows is used to set the adaptive threshold. A threshold multiplier(or scaling factor)is used to scale the threshold to achieve the desired probability of false-alarm. In the first part of this report, we have proposed two modified cell-averaging detectors for multiple target situations. The first...
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In this paper, we consider an adaptive single dwell serial search system of pseudo-noise (PN) sequence s for direct sequences spread-spectrum (DS-SS) systems in no fading additive white Gaussian noise channels. Since the received signal... more
In this paper, we consider an adaptive single dwell serial search system of pseudo-noise (PN) sequence s for direct sequences spread-spectrum (DS-SS) systems in no fading additive white Gaussian noise channels. Since the received signal levels in mobile communications are unknown and location varying, the acquisition schemes for pseudo-n oise (PN) sequences with fixed thresholds may cause too many false alarms. Therefore, adaptively varying thresh old schemes are proposed through the use of a constant false alarm rate (CFAR) algorithm. From the simulation results, w e observe that the DS/CDMA systems with CFAR processor outperforms the conventional scheme with fixed threshold.
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The effect of the PRF on the performances of the reduced rank STAP is discussed. The numerical evaluation is based on three different models of changing the PRF, namely quadratic, pseudorandom and chaotic with two methods of reduction of... more
The effect of the PRF on the performances of the reduced rank STAP is discussed. The numerical evaluation is based on three different models of changing the PRF, namely quadratic, pseudorandom and chaotic with two methods of reduction of the rank: Principle Components (PC) and Signal to Interference Noise Ratio (SINR metric). Rank reduction reduces the computing time and cost. The simulation results show that the change of PRF solves well the problem of ambiguities while using a reduced rank of covariance matrix of the environment. Also, a comparative study shows that the chaotic change is better and this is due to the simplicity of the generation of the impulses on one hand while basing itself on simple electronic circuits, such as the circuit of Chua, and on the other hand, the possibility of taking a large variety of PRFs at the same time. In fact, we use the properties of a chaotic system, to sweep all the space.
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We propose to upgrade the performance of a class of random access protocols for wireless digital networks with smart antennas operating in the presence of Rayleigh slowly fading multipath transmission channels. The capture model assumed... more
We propose to upgrade the performance of a class of random access protocols for wireless digital networks with smart antennas operating in the presence of Rayleigh slowly fading multipath transmission channels. The capture model assumed is a threshold model based on the signal to noise ratio, while the MAC protocol deployed isthe two-cell random access algorithm, in a network environment where nodesare equipped with adaptive array smart antennas. The deployed protocol relies on the ability of the antenna to deploy Direction of Arrival (DoA) algorithms, to identify the direction of transmitters and to subsequently beam-form accordingly for Signalto Interference and Noise Ratio (SINR) maximization. The performance of the protocol is evaluated using analytical modeling as well as Monte Carlo simulations usingMATLAB, where we demonstrate the benefits of using smart antennas.
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ABSTRACT The problem of adaptive CFAR regulation in a pulse-to-pulse partially Rayleigh correlated clutter is addressed. The clutter is modeled as a first-order Markov Gaussian process and its covariance matrix is assumed to be known. The... more
ABSTRACT The problem of adaptive CFAR regulation in a pulse-to-pulse partially Rayleigh correlated clutter is addressed. The clutter is modeled as a first-order Markov Gaussian process and its covariance matrix is assumed to be known. The theorem of residues is used to derive an exact expression for the probability of false alarm Pfa for the mean level (ML) detector. We show that it depends on the degree f pulse-to-pulse correlation of the clutter samples.
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ABSTRACT In automatic radar detection, performance of time diversity systems is proved to be sensitive to how the multiple-pulse sample echoes, from commonly encountered nohomogeneities, are accumulated within the same receiver. Based... more
ABSTRACT In automatic radar detection, performance of time diversity systems is proved to be sensitive to how the multiple-pulse sample echoes, from commonly encountered nohomogeneities, are accumulated within the same receiver. Based upon the ldquonon conventional time diversity systemrdquo(NCTDS), we derive exact expressions for the probabilities of false alarm and detection of a pulse-to pulse partially correlated chi-square target with 2K degrees of freedom for the trimmed mean constant false alarm rate (TM-CFAR) detector. Because of the complex mathematics induced by the ldquoconventional time diversity systemrdquo (CTDS), detection performance of this system is carried out using Monte Carlo simulations. The extensive simulation results show that, while the NCTDS achieves a better nonuniform clutter resilience than the CTDS, the latter outperforms the former in multiple target situations. Hence, when both nonhomogeneities are concomitantly present, the two systems performances become nearly similar.
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ABSTRACT
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ABSTRACT In this paper, we propose an adaptive non-coherent serial pseudo-noise (PN) acquisition scheme for code division multiple access (CDMA) communication systems. Acquisition systems based on a fixed threshold may not be able to... more
ABSTRACT In this paper, we propose an adaptive non-coherent serial pseudo-noise (PN) acquisition scheme for code division multiple access (CDMA) communication systems. Acquisition systems based on a fixed threshold may not be able to adapt to varying mobile communication environments leading to a high false alarm rate and/or a low detection probability. Accordingly, an adaptively varying threshold scheme based on artificial neural networks, namely the artificial neural networks constant false alarm rate (ANN-CFAR) algorithm for the serial system under consideration to improve the detection performance. The performance of the proposed system in terms of probability of detection, false alarm rate and mean acquisition time in a nonhomogenous Gaussian channel is studied and compared with those of the conventional adaptive acquisition scheme based on CA-CFAR and OS-CFAR detectors.
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Non-Rayleigh clutter statistics result when sea or ground clutter are viewed with resolution radars (pulse widh<0.5μs) at low grazing angle... more
Non-Rayleigh clutter statistics result when sea or ground clutter are viewed with resolution radars (pulse widh<0.5μs) at low grazing angle (ϕ<5°). In this paper, we consider the problem of Clutter Map Constant False Alarm Rate detection (CMAP-CFAR) in Weibull distribution with a shape parameter known. The target is assumed to be fluctuating according to Swerling I model. Closed-form expressions for
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A distributed constant false alarm rate (CFAR) detector with data fusion when a clutter power transition and partially correlated Rayleigh targets are present in the range resolution cells is discussed. It is shown that by appropriately... more
A distributed constant false alarm rate (CFAR) detector with data fusion when a clutter power transition and partially correlated Rayleigh targets are present in the range resolution cells is discussed. It is shown that by appropriately selecting the fusion rule at the data fusion center, the detection performance may be less sensitive to the degree of correlation among the received pulses. Analytical expressions for the overall probability of detection and the overall probability of false alarm for a general target correlation model and any M-out-of-L fusion rule are derived.
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A challenging problem in radar signal processing is to achieve reliable target detection in the presence of interferences. In this paper, we propose a novel algorithm for automatic censoring of radar interfering targets in log-normal... more
A challenging problem in radar signal processing is to achieve reliable target detection in the presence of interferences. In this paper, we propose a novel algorithm for automatic censoring of radar interfering targets in log-normal clutter. The proposed algorithm, termed the forward automatic censored cell averaging detector (F-ACCAD), consists of two steps: removing the corrupted reference cells (censoring) and the
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In radar signal detection, the problem is to automatically detect a target in a nonstationary noise and clutter background while maintaining a constant probability of false-alarm. Classical detection using a matched filter receiver and a... more
In radar signal detection, the problem is to automatically detect a target in a nonstationary noise and clutter background while maintaining a constant probability of false-alarm. Classical detection using a matched filter receiver and a fixed threshold is not applicable due to the nonstationary nature of the background noise. Therefore, adaptive threshold techniques are needed to maintain a constant false-alarm rate (CFAR). One approach to adaptive detection in nonstationary noise and clutter background is to compare the processed target signal to an adaptive threshold. In the cell-averaging CFAR processing, an estimate of the background noise from the leading and the lagging reference windows is used to set the adaptive threshold. A threshold multiplier (or scaling factor) is used to scale the threshold to achieve the desired probability of false-alarm. Two modified cell-averaging detectors for multiple target situations are proposed. The theory of distributed CFAR detection with data fusion is developed. Two topologies, namely, a parallel and a tandem topology are investigated. The overall systems are optimized so that the probability of detection is maximum while CFAR is achieved.
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ABSTRACT
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In this paper, we consider the analysis of the acquisition process for a hybrid double-dwell system with antenna diversity for DS-CDMA (direct sequence-code division multiple access) using an adaptive threshold. Acquisition systems with a... more
In this paper, we consider the analysis of the acquisition process for a hybrid double-dwell system with antenna diversity for DS-CDMA (direct sequence-code division multiple access) using an adaptive threshold. Acquisition systems with a fixed threshold value are unable to adapt to fast varying mobile communications environments and may result in a high false alarm rate, and/or low detection probability. Therefore, we propose an adaptively varying threshold scheme through the use of a cell- averaging constant false alarm rate (CA-CFAR) algorithm, which is well known in the field of radar detection. We derive exact expressions for the probabilities of detection and false alarm in Rayleigh fading channels. The mean acquisition time of the system under consideration is also derived. The performance of the system is analyzed and compared to that of a hybrid single dwell system. Keywords—Adaptive threshold, hybrid double-dwell system, CA-CFAR algorithm, DS-CDMA. I. INTRODUCTION PREAD sp...
A new robust order statistic-based CFAR scheme, the moving ordered statistics (MOS) CFAR detector, is proposed. The MOS-CFAR detector effectively estimates the noise level in nonhomogeneous backgrounds by using the spatial subspace... more
A new robust order statistic-based CFAR scheme, the moving ordered statistics (MOS) CFAR detector, is proposed. The MOS-CFAR detector effectively estimates the noise level in nonhomogeneous backgrounds by using the spatial subspace concept and the order statistics estimation method. Like the OS-CFAR detector, the MOS-CFAR processor selects one of the reference cells as the estimate of the background noise power. However, the rank of the selected sample is a variable and varies depending on the different background noise distributions in the reference cells. The detection performances of the MOS-CFAR processor is investigated and compared with other well known CFAR detectors by means of simulations. The results show that the proposed MOS-CFAR detector is superior to the other schemes in regulating the false alarm rate in nonhomogeneous backgrounds
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Image registration plays a critically important role in remote sensing applications. Due to the large volumes of remote-sensing data available today, automated registration of multitemporal and/or multisensor images is highly desired. In... more
Image registration plays a critically important role in remote sensing applications. Due to the large volumes of remote-sensing data available today, automated registration of multitemporal and/or multisensor images is highly desired. In this work, a new automatic approach for elastic image registration of remotely sensed images is proposed. The critical elements for an automated image registration procedure are explored. The elements include control-point (CP) extraction, CP matching, and transformation parameters estimation. In the proposed algorithm, a new CPs extractor has been developed. This technique exploits the nonsubsampled contourlet transform (NSCT) to automatically extract a set of CPs where misalignment between images can be expected to appear. The proposed algorithm has been successfully applied to register multitemporal ALSAT-1 images from urban and agricultural areas. The experimental results demonstrate the robustness, efficiency and accuracy of the proposed algori...
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A distributed version of a signal detection problem of practical relevance is considered. It deals with the detection of a target in a statistically nonstationary background noise (thermal noise plus cutter). In this situation, classical... more
A distributed version of a signal detection problem of practical relevance is considered. It deals with the detection of a target in a statistically nonstationary background noise (thermal noise plus cutter). In this situation, classical detection with a fixed threshold cannot be used because the false-alarm probability may increase intolerably. Therefore, adaptive threshold techniques are needed to maintain a constant
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This paper proposes an adaptive pseudonoise (PN) code acquisition system that adopts smart antennas and a cell averaging constant false alarm rate (CA-CFAR) processor to achieve reliable PN code acquisition in the presence of fading and... more
This paper proposes an adaptive pseudonoise (PN) code acquisition system that adopts smart antennas and a cell averaging constant false alarm rate (CA-CFAR) processor to achieve reliable PN code acquisition in the presence of fading and interference. Hence, the decision threshold is adjusted according to the varying environment in order to improve the detection performance. The performance of the proposed system has been assessed theoretically by deriving closed form expressions for the probability of detection and probability of false alarm. The mean acquisition time is also obtained, and simulation results have been presented to verify the derived theoretical analysis.
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ABSTRACT In this paper, we propose an automatic censoring detector using binary clutter map estimation, for multiple target situations and compound dominated-clutters. The proposed censoring procedure dynamically discards the unwanted... more
ABSTRACT In this paper, we propose an automatic censoring detector using binary clutter map estimation, for multiple target situations and compound dominated-clutters. The proposed censoring procedure dynamically discards the unwanted samples by implementing an adaptive pre-thresholding, for the incoming clutter echoes. Thus, the obtained decisions are sent serially into a shift register to form the binary clutter map (BCM) estimation. Finally, the logical states of the clutter map register are used to yield the background level estimation. To show the robustness of the clutter map-based detection scheme, the effects of speckle correlation and interfering targets on the censoring efficiency are analyzed.
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Multipath detection is very important for the proper operation of wideband communication systems. Conventional detectors using constant threshold result in suboptimal performance since they either fail to detect a multipath component or... more
Multipath detection is very important for the proper operation of wideband communication systems. Conventional detectors using constant threshold result in suboptimal performance since they either fail to detect a multipath component or provide a wrong path to the receiver. In this paper, two adaptive constant false alarm rate (CFAR) multipath detectors are proposed: cell-averaging CA-CFAR and order-statistics OS-CFAR. An experimental
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ABSTRACT In this paper, we study the problem of automatic target detection in Weibull clutter and multiple target situations, without any prior knowledge of neither the non-stationary clutter statistics in which the radar operates nor the... more
ABSTRACT In this paper, we study the problem of automatic target detection in Weibull clutter and multiple target situations, without any prior knowledge of neither the non-stationary clutter statistics in which the radar operates nor the number of outliers that may be present in the reference window. In doing this, we develop the Forward/Backward Order Statistic Automatic Censoring and Detection Constant False Censoring and Alarm Rates Detectors based upon the Weber-Haykin adaptive threshold (WH-based F/B-OSACD-CFCAR). These detectors select repeatedly a suitable set of ranked cells among reference cells surrounding the cell under test to estimate the unknown background level and set the adaptive threshold, accordingly. The censoring and detection performances are evaluated by means of Monte Carlo simulations.
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In this paper, we investigate the use of two iterative algorithms for the suppression of interferences and thus, the detection of slow targets in monostatic airborne radar. The conventional space-time adaptive processing (STAP) such as... more
In this paper, we investigate the use of two iterative algorithms for the suppression of interferences and thus, the detection of slow targets in monostatic airborne radar. The conventional space-time adaptive processing (STAP) such as the sample matrix inversion (SMI) or the Principal Components (PC) methods are computationally costly and require the estimation of the clutter covariance matrix from secondary
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... MLE-Based Order Statistic Automatic CFCAR Detection in Weibull Background Souâd Chabbi,Toufik Laroussi, and Mourad Barkat, Fellow IEEE I ACTEA 2009 July 15-17, 2009 Zouk Mosbeh, Lebanon 978-1-4244-3834-1/09/$25.00 © 2009 IEEE 541 Page... more
... MLE-Based Order Statistic Automatic CFCAR Detection in Weibull Background Souâd Chabbi,Toufik Laroussi, and Mourad Barkat, Fellow IEEE I ACTEA 2009 July 15-17, 2009 Zouk Mosbeh, Lebanon 978-1-4244-3834-1/09/$25.00 © 2009 IEEE 541 Page 2. Fig. ...
Research Interests: Statistics, Monte Carlo Simulation, Probability, Monte Carlo Simulations, Monte Carlo Methods, and 10 morePrior Knowledge, Detectors, Maximum Likelihood Estimation, Computational, Target Detection, Weibull distribution, Adaptive Thresholding, Detection Algorithm, maximum likelihood estimate, and Order statistic
In this paper, we first present the principles of STAP and discuss the properties of optimum detector, as well as problems associated with estimating the adaptive weights such as ambiguities and the high computational cost. The... more
In this paper, we first present the principles of STAP and discuss the properties of optimum detector, as well as problems associated with estimating the adaptive weights such as ambiguities and the high computational cost. The performances are evaluated highlighting the influence of radar parameters on the detection of slow targets. To resolve problem of high computational cost of optimal
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... Chahira Serief*, Mourad Barkat**, and Youcef Bentoutou* * National Center of Space Techniques (CNTS), 01 Avenue de la Palestine, Arzew, 31200 ... [3] AL Cunha, J. Zhou, and MN Do, “The Nonsubsampled Contourlet Transform: Theory,... more
... Chahira Serief*, Mourad Barkat**, and Youcef Bentoutou* * National Center of Space Techniques (CNTS), 01 Avenue de la Palestine, Arzew, 31200 ... [3] AL Cunha, J. Zhou, and MN Do, “The Nonsubsampled Contourlet Transform: Theory, Design, and Applications,” IEEE Trans. ...