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Aerospace and Electronic Systems, IEEE Transactions on

Issue 3 • Date July 2005

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  • IEEE Transactions on Aerospace and Electronic Systems - Table of contents

    Publication Year: 2005 , Page(s): 0_1
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  • IEEE copyright transfer form

    Publication Year: 2005 , Page(s): 02
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  • From the editors

    Publication Year: 2005 , Page(s): 769
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  • Nonlinear adaptive spacecraft attitude control using solar radiation pressure

    Publication Year: 2005 , Page(s): 770 - 779
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB) |  | HTML iconHTML  

    Spacecraft and interplanetary probes orbiting at high altitudes experience forces due to solar radiation pressure, which can be used for maneuvering. The question of large angle pitch attitude maneuvers of satellites using solar radiation torque is considered. For pitch axis maneuver, two highly reflective control surfaces are used to generate radiation moment. The solar radiation moment is a complex nonlinear function of the attitude and parameters of the satellite, the orbital parameters, and the deflection angles of the reflective control surfaces. It is assumed that the parameters of the satellite model are unknown. Based on a backstepping design technique, a nonlinear adaptive control law is derived for the control of the pitch angle. In the closed-loop system, the pitch angle asymptotically tracks prescribed reference trajectories. Simulation results are presented to show that the adaptive control system accomplishes attitude control of the satellite in spite of the parameter uncertainties in the system. View full abstract»

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  • Two-step optimal estimator for three dimensional target tracking

    Publication Year: 2005 , Page(s): 780 - 793
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (819 KB) |  | HTML iconHTML  

    This study presents an adaptation of a novel estimation methodology to the general nonlinear three-dimensional problem of tracking a maneuvering target. The two-step optimal estimator (TSE) suggests an attractive alternative to the standard extended Kalman filter (EKF). A superior performance is accomplished by dividing the estimation problem into two steps: a linear first step and a nonlinear second step. The target tracking performance of the TSE is shown to be better than an EKF implemented in either inertial or modified spherical coordinates. In the passive case, where bearing/elevation angles only are measured, the TSE yields excellent range and target acceleration estimates. In the active case, where range measurement is available as well, a homing missile employing closed-loop optimal guidance based on the TSE state estimates obtains smaller miss distances than with either versions of the EKF. View full abstract»

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  • Temporally staggered sensors in multi-sensor target tracking systems

    Publication Year: 2005 , Page(s): 794 - 808
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (853 KB) |  | HTML iconHTML  

    For a multi-sensor target tracking system, the effects of temporally staggered sensors on system performance are investigated and compared with those of synchronous sensors. To capture system performance over time, a new metric, the average estimation error variance (AEV), is proposed. For a system that has N sensors with equal measurement noise variance, numerical results show that the optimal staggering pattern is to use N uniformly staggered sensors. We have also shown analytically that the AEV of the system with N uniformly staggered sensors is always smaller than that of the system with N synchronous sensors. For sensors with different measurement noise variances, the optimal staggering pattern can be found numerically. Practical guidelines on selecting the optimal staggering pattern have been presented for different target tracking scenarios. Due to its simplicity, uniform staggering can be used as an alternative scheme with relatively small performance degradation. View full abstract»

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  • Emitter number estimation from pulse trains using the GIC

    Publication Year: 2005 , Page(s): 809 - 818
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (361 KB) |  | HTML iconHTML  

    An information theoretic criterion based approach for estimating the number of emitters from a set of interleaved pulse trains is proposed. In the approach, a new pulse signal model is formulated to handle large number of pulses. The approach is based on the application of the general information criteria (GIC) and has the advantage of not requiring any threshold setting procedures. When compared with classical information theoretic criterion based approaches, the GIC-based approach is more flexible, and it does not involve any computationally sophisticated maximum likelihood estimator. Computer simulations are used to demonstrate the effectiveness of the proposed approach. View full abstract»

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  • Line-of-sight-pointing for satellites in high altitude inclined elliptic orbits

    Publication Year: 2005 , Page(s): 819 - 829
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (726 KB) |  | HTML iconHTML  

    With a growing demand for space communications and resulting overcrowding of geostationary orbit (GEO), the importance of high altitude inclined elliptic orbits is gaining impetus. However, the satellites in these orbits suffer from a severe problem of apparent periodic angular drift around their line-of-sight. This paper addresses this problem and proposes a cost effective method based on tether to continually tilt the satellites in order to compensate for longitudinal and lateral drifts relative to the ground station. The proposed system comprises two satellites connected by a flexible tether at a point on each satellite with offsets. A control strategy is developed for tether offset variations that ensures judiciously controlled changes in the satellite orientations. The numerical simulation of the governing nonlinear equations of motion establishes the feasibility of the concept. A high degree of line-of-sight pointing of dual satellites as well as the simplicity of the proposed control mechanism makes the concept particularly attractive for future space applications. View full abstract»

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  • Analytic study of Doppler-based handover management in LEO satellite systems

    Publication Year: 2005 , Page(s): 830 - 839
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (443 KB) |  | HTML iconHTML  

    The problem of dynamic handover management in low Earth orbit (LEO) satellite systems is addressed. Particularly, an analytical study of a newly proposed method for handover management, called dynamic Doppler-based handover prioritization scheme (DDBHP), is presented. DDBHP utilizes Doppler shift monitoring of each communicating user terminal onboard the satellite and geometric characteristics to accurately predict the handover load. As a result, handover requests are more effectively managed, resulting in an improved performance in terms of blocking and forced termination probabilities. Moreover, by supporting guaranteed handovers, DDBHP can be used to provide QoS to users of future broadband satellite networks. An extensive mathematical model that justifies Doppler shift monitoring is presented along with a detailed queueing model used not only to evaluate DDBHP performance but also to provide a methodology for associating DDBHP operational parameters with desired performance. Comparison of analytical and simulation results validate the proposed model. View full abstract»

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  • Applications of level crossing theory to target intervisibility: to be seen or not to be seen?

    Publication Year: 2005 , Page(s): 840 - 852
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1908 KB) |  | HTML iconHTML  

    Here we discuss intervisibility (the existence of an unobstructed line of sight (LOS) between two points) accounting for the vertical and horizontal errors in the estimated locations of both points as well as elevation errors in the database of the terrain that could obstruct the LOS between these points. The errors are first simply treated as a "white" noise sequence: we assume no correlation between the intervisibility at two different times, and the probability of an instantaneous intervisibility event is in this case developed. This is useful; but perhaps of greater concern is whether or not a target remains visible long enough and/or often enough that its motion can be tracked? Consequently, we present a second treatment in which the errors are stochastic processes of a certain bandwidth, and both the probability density function (pdf) of an intervisibility interval and the average number of intervisibility intervals over a certain time period are developed. View full abstract»

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  • Multiple-model estimation with variable structure- part VI: expected-mode augmentation

    Publication Year: 2005 , Page(s): 853 - 867
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (844 KB) |  | HTML iconHTML  

    A new class of variable-structure (VS) algorithms for multiple-model (MM) estimation is presented, referred to as expected-mode augmentation (EMA). In the EMA approach, the original set of models is augmented by a variable set of models intended to match the expected value of the unknown true mode. These models are generated adaptively in real time as (globally or locally) probabilistically weighted sums of mode estimates over the model set. This makes it possible to cover a large continuous mode space by a relatively small number of models at a given accuracy level. The paper presents new theoretical results for model-set design, a general formulation of the EMA approach, along with theoretical analysis and justification, and three algorithms for its practical implementation. The performance of the proposed EMA algorithms is evaluated via simulation of a generic maneuvering target tracking problem. View full abstract»

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  • Tracking with classification-aided multiframe data association

    Publication Year: 2005 , Page(s): 868 - 878
    Cited by:  Papers (30)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (842 KB) |  | HTML iconHTML  

    In most conventional tracking systems, only the target kinematic information from, for example, a radar or sonar or an electro-optical sensor, is used in measurement-to-track association. Target class information, which is typically used in postprocessing, can also be used to improve data association to give better tracking accuracy. The use of target class information in data association can improve discrimination by yielding purer tracks and preserving their continuity. In this paper, we present the simultaneous use of target classification information and target kinematic information for target tracking. The approach presented integrates target class information into the data association process using the 2-D (one track list and one measurement list) as well as multiframe (one track list and multiple measurement lists) assignments. The multiframe association likelihood is developed to include the classification results based on the "confusion matrix" that specifies the accuracy of the target classifier. The objective is to improve association results using class information when the kinematic likelihoods are similar for different targets, i.e., there is ambiguity in using kinematic information alone. Performance comparisons with and without the use of class information in data association are presented on a ground target tracking problem. Simulation results quantify the benefits of classification-aided data association for improved target tracking, especially in the presence of association uncertainty in the kinematic measurements. Also, the benefit of 5-D (or multiframe) association versus 2-D association is investigated for different quality classifiers. The main contribution of this paper is the development of the methodology to incorporate exactly the classification information into multidimensional (multiframe) association. View full abstract»

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  • Digital channelized receiver based on time-frequency analysis for signal interception

    Publication Year: 2005 , Page(s): 879 - 898
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1592 KB) |  | HTML iconHTML  

    A digital channelized receiver is presented for the interception of a wide variety of signals of complex structure, including those with low probability of interception. The receiver is designed from the perspective of the time-frequency analysis. It uses an extended time-frequency representation based on the noncoherent integration of the short-time Fourier transform (STFT) on which the detection system and the encoder work. The encoder includes robust frequency estimation, automatic modulation recognition, and clustering, to handle broadband and simultaneous signals and to prevent out-of-channel detections (a typical phenomenon in channelized receivers). The receiver has been evaluated for a wide range of signals and shows a good performance in terms of detection, estimation, and processing of simultaneous signals. Signals collected from real-life systems and synthetic signals have been utilized. View full abstract»

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  • Multisensor multitarget bias estimation for general asynchronous sensors

    Publication Year: 2005 , Page(s): 899 - 921
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2961 KB) |  | HTML iconHTML  

    A novel solution is provided for the bias estimation problem in multiple asynchronous sensors using common targets of opportunity. The decoupling between the target state estimation and the sensor bias estimation is achieved without ignoring or approximating the crosscovariance between the state estimate and the bias estimate. The target data reported by the sensors are usually not time-coincident or synchronous due to the different data rates. Since the bias estimation requires time-coincident target data from different sensors, a novel scheme is used to transform the measurements from the different times of the sensors into pseudomeasurements of the sensor biases with additive noises that are zero-mean, white, and with easily calculated covariances. These results allow bias estimation as well as the evaluation of the Cramer-Rao lower bound (CRLB) on the covariance of the bias estimate, i.e., the quantification of the available information about the biases in any scenario. Monte Carlo simulation results show that the new method is statistically efficient, i.e., it meets the CRLB. The use of this technique for scale and sensor location biases in addition to the usual additive biases is also presented. View full abstract»

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  • Adaptive imaging for forward-looking ground penetrating radar

    Publication Year: 2005 , Page(s): 922 - 936
    Cited by:  Papers (5)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2572 KB) |  | HTML iconHTML  

    Most of the current forward-looking ground-penetrating radar (FLGPR) systems use conventional delay-and-sum (DAS) based methods to form radar images for detection of the target (such as a landmine). However, DAS is a data-independent approach which is known to suffer from low resolution and poor interference and clutter rejection capability. We present a data-adaptive imaging approach for FLGPR image formation based on APES (amplitude and phase estimation) and rank-deficient RCB (robust Capon beamforming). Due to the data-adaptive nature of both APES and RCB, our approach has better resolution and much better interference and clutter rejection capability than the standard DAS-based imaging methods. The excellent performance of the proposed method is demonstrated using experimental data collected via two FLGPR systems recently developed by PSI (Planning Systems, Inc.) and SRI (Stanford Research Institute). View full abstract»

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  • Track-before-detect procedures for early detection of moving target from airborne radars

    Publication Year: 2005 , Page(s): 937 - 954
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1042 KB) |  | HTML iconHTML  

    In this paper we present a family of track-before-detect (TBD) procedures for early detection of moving targets from airborne radars. Upon a sectorization of the coverage area, the received echoes are jointly processed in the azimuth-range-Doppler domain and in the time domain through a Viterbi-like algorithm that exploits the physically admissible target transitions between successive illuminations, in order to collect all of the energy back-scattered during the time on target (TOT). A reduced-complexity implementation is derived assuming, at the design stage, that the target does not change resolution cell during the TOT in each scan. The constant false alarm rate (CFAR) constraint is also englobed in the proposed procedures as well as the possibility of working with quantized data. Simulation results show that the proposed algorithms have good detection and tracking capabilities even for high target velocities and low quantization rates. View full abstract»

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  • W-band airborne interrupted frequency modulated CW imaging radar

    Publication Year: 2005 , Page(s): 955 - 972
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3321 KB) |  | HTML iconHTML  

    A 94 GHz imaging radar-based on the interrupted FMCW (FMICW) principles, with its associated gimbals for stabilization and scanning has been developed as an airborne test-bed to evaluate radar-aided navigation and guidance algorithms. Preliminary results from helicopter-based flight tests show sufficient contrast between selected features (including runways) and their surroundings for both computer- and human-pilot-based guidance. Feature extraction and matching algorithms have shown this system to be more accurate than GPS. View full abstract»

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  • Adaptive learning approach to landmine detection

    Publication Year: 2005 , Page(s): 973 - 985
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2659 KB) |  | HTML iconHTML  

    We consider landmine detection using forward-looking ground penetrating radar (FLGPR). The two main challenging tasks include extracting intricate structures of target signals and adapting a classifier to the surrounding environment through learning. Through the time-frequency (TF) analysis, we find that the most discriminant information is TF localized. This observation motivates us to use the over-complete wavelet packet transform (WPT) to sparsely represent signals with the discriminant information encoded into several bases. Then the sequential floating forward selection method is used to extract these components and thereby a neural network (NNW) classifier is designed. To further improve the classification performance and deal with the problem of detecting mines in an unconstraint environment, the AdaBoost algorithm is used. We integrate the feature selection process into the original AdaBoost algorithm. In each iteration, AdaBoost identifies the hard-to-learn examples and a new set of features which provide the specific discriminant information for these hard samples is extracted adaptively and a new classifier is trained. Experimental results based on measured data are presented, showing that a significant improvement on the classification performance can be achieved. View full abstract»

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  • IMM estimator versus optimal estimator for hybrid systems

    Publication Year: 2005 , Page(s): 986 - 991
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (409 KB) |  | HTML iconHTML  

    The special feature of the interacting multiple model (TMM) estimator that distinguishes it from other suboptimal multiple model (MM) estimators is the "mixing/interaction" between its "mode-matched" base state filtering modules at the beginning of each cycle. This note shows that the same feature is exactly what it has in common with the optimal estimator for hybrid (MM) systems and this can be seen as the main reason for its success. View full abstract»

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  • Time windowing for highly focused ISAR image reconstruction

    Publication Year: 2005 , Page(s): 992 - 1007
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3008 KB) |  | HTML iconHTML  

    In several applications long recorded live inverse synthetic aperture radar (ISAR) data are used to obtain one or more ISAR images. In order to reconstruct a well-focused ISAR image, a suitable selection of the echoes to be coherently processed must be provided. Such a selection can be made by defining a time window. We propose a technique for the automatic selection of the position and length of the time window that provides the ISAR image with the highest focus. The technique, namely the maximum contrast based automatic time window selection (MC-ATWS), is based on the definition of image contrast (IC). Due to the fact that the IC is a measure of the image focus, the time window is selected by maximizing the IC. The technique effectiveness is tested by using simulated and real data. View full abstract»

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  • Novel hybrid 12-pulse boost-type rectifier with controlled output voltage

    Publication Year: 2005 , Page(s): 1008 - 1018
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2403 KB) |  | HTML iconHTML  

    Novel hybrid 12-pulse line interphase transformer (LIT) rectifier systems with integrated single-switch or two-switch boost-type output stage that ensure a constant output voltage independent of mains and load conditions are proposed for supplying actuators of future more electric aircraft. The principle of operation, the dimensioning, and the system control are discussed. The theoretical considerations are experimentally confirmed for a 10 kW laboratory prototype. Finally, the single-and the two-switch system are comparatively evaluated concerning the level of input current ripple, power factor, and overall efficiency. View full abstract»

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  • Power tracking for nonlinear PV sources with coupled inductor SEPIC converter

    Publication Year: 2005 , Page(s): 1019 - 1029
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (451 KB) |  | HTML iconHTML  

    The photovoltaic (PV) generator exhibits a nonlinear i-v characteristic and its maximum power (MP) point varies with solar insolation. In this paper, a V2-based MP point tracking (MPPT) scheme is developed using a buck-boost transformation topology. Although several buck-boost transformation topologies are available we have considered here a coupled inductor SEPIC converter for experimentation. To achieve almost ripple-free array current we have used ripple steering phenomena with the help of integrated inductor. This integrated inductor not only reduces the magnetic core requirements but also improves converter performance. Mathematical models are formulated and tracking algorithm is evolved. A combined PV system simulation model is developed in the SIMULINK. For a given solar insolation, the tracking algorithm changes the duty ratio of the converter such that the solar cell array (SCA) voltage equals the voltage corresponding to the MP point. This is done by the tracking algorithm, which mainly computes the power proportional to square of terminal voltage and changes the duty ratio of the converter so that this power is maximum. The proposed algorithm is implemented in real-time with the help of Analog Device ADMC-401 DSP evaluation module. The tracking program is developed to perform experimental investigations using analog-to-digital converter (ADC) interrupt. Using this processor we are able to track the MP within 200 ms. The proposed peak power tracking effectiveness is demonstrated through simulation and experimental results. View full abstract»

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  • EM-ML algorithm for track initialization using possibly noninformative data

    Publication Year: 2005 , Page(s): 1030 - 1048
    Cited by:  Papers (4)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1294 KB) |  | HTML iconHTML  

    Initializing and maintaining a track for a low observable (LO) (low SNR, low target detection probability and high false alarm rate) target can be very challenging because of the low information content of measurements. In addition, in some scenarios, target-originated measurements might not be present in many consecutive scans because of mispointing, target maneuvers, or erroneous preprocessing. That is, one might have a set of noninformative scans that could result in poor track initialization and maintenance. In this paper an algorithm based on the expectation-maximization (EM) algorithm combined with maximum likelihood (ML) estimation is presented for tracking slowly maneuvering targets in heavy clutter and possibly noninformative scans. The adaptive sliding-window EM-ML approach, which operates in batch mode, tries to reject or weight down noninformative scans using the Q-function in the M-step of the EM algorithm. It is shown that target features in the form of, for example, amplitude information (AI), can also be used to improve the estimates. In addition, performance bounds based on the supplemented EM (SEM) technique are also presented. The effectiveness of new algorithm is first demonstrated on a 78-frame long wave infrared (LWIR) data sequence consisting of an Fl Mirage fighter jet in heavy clutter. Previously, this scenario has been used as a benchmark for evaluating the performance of other track initialization algorithms. The new EM-ML estimator confirms the track by frame 20 while the ML-PDA (maximum likelihood estimator combined with probabilistic data association) algorithm, the IMM-MHT (interacting multiple model estimator combined with multiple hypothesis tracking) and the EVIM-PDA estimator previously required 28, 38, and 39 frames, respectively. The benefits of the new algorithm in terms of accuracy, early detection, and computational load are illustrated using simulated scenarios as well. View full abstract»

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  • Universal equations for radar target detection

    Publication Year: 2005 , Page(s): 1049 - 1052
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (302 KB) |  | HTML iconHTML  

    Two equations express detection probability and detectability factor for all Swerling targets and for partially correlated intermediate cases. View full abstract»

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  • Improved motion-mode estimation

    Publication Year: 2005 , Page(s): 1052 - 1056
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (222 KB) |  | HTML iconHTML  

    Hybrid trackers incorporating a non-Markov modal model have been proposed. However, these algorithms use a restricted measurement set to identify the modal state. It is shown here that a renewal process model, along with broader measurement fusion, enhances modal classification in such estimators. View full abstract»

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Aims & Scope

IEEE Transactions on Aerospace and Electronic Systems focuses on the equipment, procedures, and techniques applicable to the organization, installation, and operation of functional systems designed to meet the high performance requirements of earth and space systems.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Lance Kaplan
Army Research Laboratory