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Aerospace and Electronic Systems, IEEE Transactions on

Issue 3 • Date July 2013

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  • Table of Contents

    Publication Year: 2013 , Page(s): c1
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  • Cover 2

    Publication Year: 2013 , Page(s): c2
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  • From the Editor-In-Chief

    Publication Year: 2013 , Page(s): 1
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  • Change Detection Analysis of Humans Moving Behind Walls

    Publication Year: 2013 , Page(s): 1410 - 1425
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5545 KB) |  | HTML iconHTML  

    In this paper, we consider the problem of detection of humans behind walls and inside enclosed structures using radars. We use change detection techniques to mitigate the heavy clutter caused by strong reflections from exterior and interior walls. To improve spatial resolution, we apply multiple-input multiple-output (MIMO) configurations to moving target indication (MTI). We examine change detection formulation and performance when clutter removal is performed pre- and postbeamforming. Using signal multiplexing from two transmitters and several receiver positions, we show that the virtual array (coarray) implementing the prebeamforming change detection MIMO scheme permits enhanced clutter rejection and improvement in imaging resolution of moving targets without increasing the physical aperture. Laboratory experiments are conducted to validate the proposed approaches with targets walking behind walls. View full abstract»

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  • Nearly Orthogonal Waveforms for MIMO FMCW Radar

    Publication Year: 2013 , Page(s): 1426 - 1437
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5094 KB) |  | HTML iconHTML  

    Herein is proposed a set of nearly orthogonal waveforms based on offset linear frequency modulated (LFM) signals for multiple-input, multiple-output frequency modulated continuous wave (MIMO FMCW) radar operation. The orthogonality of sounding signals is a critical point for many multi-channel radar applications because the interference between signals can significantly limit the radar's ability for observation of weak targets in the presence of strong targets and clutter. High orthogonality for the proposed waveforms can be obtained by using de-ramping processing in the MIMO FMCW radar receiver. The experimental results presented demonstrate that a high orthogonality level is achievable for a specific multi-channel FMCW radar. View full abstract»

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  • NLOS Identification and Mitigation for Mobile Tracking

    Publication Year: 2013 , Page(s): 1438 - 1452
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4899 KB) |  | HTML iconHTML  

    A non-line-of-sight (NLOS) mitigation approach is presented for network-based mobile tracking. A distance smoothing method is proposed, which uses online line-of-sight (LOS) and NLOS identification. A technique is proposed to integrate distance, mobile velocity, and heading estimates for position determination through Kalman filtering. Hypothesis testing analysis is performed to provide a guideline for selecting the threshold values. Simulation results demonstrate that the proposed approach significantly improves position accuracy as compared with the existing algorithms. View full abstract»

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  • Real-Time UWB-OFDM Radar-Based Navigation in Unknown Terrain

    Publication Year: 2013 , Page(s): 1453 - 1466
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6264 KB) |  | HTML iconHTML  

    We present a signal processing algorithm and simulation study for aerial navigation with an ultrawideband orthogonal frequency division multiplexed (UWB-OFDM) radar in Global Positioning System (GPS)-denied environments. Stationary scatterers are detected and tracked using an M/N detector and modified global nearest neighbor (GNN) tracker. The radar measurements to the scatterers are combined with inertial navigation system (INS) measurements in an extended Kalman filter (EKF) to compute the aircraft position. The estimation error of the proposed algorithm is analyzed through computer-based simulations with/without radar measurements from the scatterers and with varying signal-to-noise ratio (SNR). View full abstract»

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  • An Autonomous Star Recognition Algorithm with Optimized Database

    Publication Year: 2013 , Page(s): 1467 - 1475
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2141 KB) |  | HTML iconHTML  

    A novel star pattern recognition algorithm is presented for satellite attitude determination in the "lost in space" mode. The proposed method improves the speed in searching a large star catalogue by arranging it using a search tree data structure. The algorithm also processes the star image at grid level instead of pixel level to further improve the processing time. The experimental results show that the proposed approach significantly reduces the average run-time by 50% as compared with the conventional methods while still achieving slightly better star recognition accuracy at 95.07%. View full abstract»

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  • Probability Hypothesis Density-Based Multitarget Tracking for Proximity Sensor Networks

    Publication Year: 2013 , Page(s): 1476 - 1496
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (10366 KB) |  | HTML iconHTML  

    An investigation of the feasibility of a mesh network of proximity sensors to track targets is presented. In such a network the sensors report binary detection/nondetection measurements for the targets within proximity. A new probability hypothesis density (PHD) filter and its particle implementation for multiple-target tracking in a proximity sensor network are proposed. The performance and robustness of the new method are evaluated over simulated matching and mismatching cases for the sensor models. The simulations demonstrate the utility of the PHD filter to both track the number of targets and their locations. View full abstract»

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  • Comparison Framework of FPGA-Based GNSS Signals Acquisition Architectures

    Publication Year: 2013 , Page(s): 1497 - 1518
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3037 KB) |  | HTML iconHTML  

    The acquisition of Global Navigation Satellite Systems (GNSS) signals using code division multiple access (CDMA) can be performed through classical correlation or using a Fourier transform. These methods are well known, but what is missing is a comparison of their performance for a given hardware area or target. The work reported here presents this comparison for field-programmable gate arrays (FPGAs), describing the different parameters involved in the acquisition, detailing some optimized implementations where hardware elements are duplicated, and estimating and discussing the performances. The influence of the Doppler effect on the code is also discussed as it plays an important role, particularly for new signals using a high chipping rate. View full abstract»

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  • A Computationally Efficient CFAR Algorithm Based on a Goodness-of-Fit Test for Piecewise Homogeneous Environments

    Publication Year: 2013 , Page(s): 1519 - 1535
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (9522 KB) |  | HTML iconHTML  

    A new constant false alarm rate (CFAR) detection algorithm operating in nonhomogeneous clutter is proposed. The proposed CFAR algorithm, cell-under-test (CUT) inclusive (CI) CFAR, utilizes a goodness-of-fit test for determining and combining homogeneous windows, which results in a higher detection performance. The CI-CFAR algorithm layout and analytical properties for the ideal case are investigated. In comparison with the traditional cell-averaging (CA) CFAR and order-statistic (OS) CFAR, it is demonstrated that CI-CFAR outperforms both in most situations. View full abstract»

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  • A Quantitative Analysis of a Novel SEU-Resistant SHA-2 and HMAC Architecture for Space Missions Security

    Publication Year: 2013 , Page(s): 1536 - 1554
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3196 KB) |  | HTML iconHTML  

    The increasing demand for more secure operation of space missions has led to emergence of cryptographic mechanisms aboard spacecrafts. However, cryptographic applications are extremely sensitive to bit-flips caused by radiation-induced single event upsets (SEUs). A traditional approach to mitigate SEUs in space applications has been the triple modular redundancy (TMR). However, such technique incurs large overheads in implementation area and power. An efficient approach to achieve fault tolerance in the secure hash standard (SHS) and in the keyed-hash message authentication code (HMAC) is introduced. When compared with TMR the proposed scheme not only achieves higher resistance against SEUs, but it also reduces implementation area requirements and power consumption. Results obtained through field-programmable gate array (FPGA) implementation show that HMAC/SHA-512 (secure hash algorithm) utilizes, on average, 53% less area and less power compared with the traditional TMR technique. Furthermore, the memory and registers of the HMAC/SHA-512 module are approximately 171 and 491 times more resistant against SEUs than TMR. This research is crucial for enabling the efficient employment of security mechanisms onboard space systems. View full abstract»

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  • Comparative Studies of GPS Multipath Mitigation Methods Performance

    Publication Year: 2013 , Page(s): 1555 - 1568
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6283 KB) |  | HTML iconHTML  

    Coupled amplitude delay lock loops (CADLL) is a recently proposed multipath estimation and mitigation technique based on joint estimation of line-of-sight (LOS) and multipath signal amplitude, code phase, and carrier phase. The CADLL performance is evaluated against two widely known multipath mitigation methods: the high-resolution correlator (HRC), representative of the correlators combination methods, and the multipath mitigation technique (MMT), representative of multipath estimation methods. Multiple tests emulating various scenarios are performed to demonstrate that CADLL always generates better results than the other two methods. Additionally, CADLL has better noise performance, can estimate multipath signals using shorter integration time, and is capable of tracking dynamic multipath signals. Simulation tests using a statistical urban multipath signal model prove that CADLL is effective in estimating and mitigating multipath in severe multipath environments. These simulation results are further validated using satellite signals generated by Spirent Global Navigation Satellite System (GNSS) 6700. View full abstract»

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  • Two-Layer Particle Filter for Multiple Target Detection and Tracking

    Publication Year: 2013 , Page(s): 1569 - 1588
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (6176 KB) |  | HTML iconHTML  

    The detection and tracking of an unknown number of targets using a Bayesian hierarchical model with target labels is presented. To approximate the posterior probability density function (PDF), we develop a two-layer particle filter (PF). One deals with track initiation, and the other deals with track maintenance. In addition the parallel partition (PP) method is proposed to sample the states of the surviving targets. View full abstract»

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  • Wind Turbine Radar Interference Studies by Polarimetric Measurements of a Scaled Model

    Publication Year: 2013 , Page(s): 1589 - 1600
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4683 KB) |  | HTML iconHTML  

    Wind turbines can cause interference to nearby radars due to strong backscattering. As a recently recognized type of radar interference, wind turbine radar signatures need to be fully studied. The scaled measurement of a wind turbine model has been proposed to characterize wind turbine radar signatures. The radar wind turbine testbed (RWT2) has been developed for such a purpose. Polarimetric radar signatures derived from measurements reveal unique features that can be exploited to help identify wind turbines from desired radar targets. View full abstract»

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  • Attitude Determination by Exploiting Geometric Distortions in Stereo Images of DMC Camera

    Publication Year: 2013 , Page(s): 1601 - 1625
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (9725 KB) |  | HTML iconHTML  

    A description is presented of a neoteric approach to determine the orientation of the spacecraft for any arbitrary attitude by exploiting the offsets in the Earth observational imagery from a pair of canted pushbroom sensors. Due to angular separation one of the imager projections is ahead of the other, which causes a delay in the imaging of the same ground features by the sensors. Thus, the angular separation creates perspective and temporal distortions in the imagery, which give rise to inter-image offsets in the overlapping region. A mathematical model is developed using the sensor configuration of the UK-DMC (disaster monitoring constellation) satellite to demonstrate how the offsets are introduced in the imagery and quantify that model with the aid of synthetic images. To determine the attitude from the image offsets, the attitude model is inverted. The accuracy of attitude estimates is highly dependent on the image texture, angular separation between the sensors, spacecraft attitude, and image registration method. With small along-track separation between the sensors, the registration time is very short, thus, changes in the inter-image offsets are not very rapid at small arbitrary rotations. However, with the increase in along-track separation between the sensors, the registration time increases, which allows changes in inter-image offsets to be discerned due to attitude variation and increases the sensitivity of the technique. But with large along-track separation, the attitude estimates are averaged over the registration time period. At small arbitrary rotations with half-a-degree angular separation between the sensors, this technique gives attitude accuracies of ±0.03°. As attitude estimates come directly from the payload rather than a dedicated sensor, this corresponds to significant savings in cost, mass, and volume, which are critical for small satellites. View full abstract»

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  • Sparse-Grid Quadrature $H_infty $ Filter for Discrete-Time Systems with Uncertain Noise Statistics

    Publication Year: 2013 , Page(s): 1626 - 1636
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4916 KB) |  | HTML iconHTML  

    In This paper H technique is combined with the recently developed sparse-grid quadrature (SGQ) filtering to improve the accuracy and robustness of the state estimation when the noise statistics is not known a priori. The proposed new SGQ H filter (SGQHF) is compared with other H filters via two numerical examples. It is shown that the SGQHF is more robust and accurate than the extended H filter, unscented H filter, and cubature H filter. In addition it maintains a close performance to the Gauss-Hermite quadrature (GHQ) H filter but is computationally much more efficient since it uses far fewer quadrature points. View full abstract»

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  • Optimal Placement of Heterogeneous Sensors for Targets with Gaussian Priors

    Publication Year: 2013 , Page(s): 1637 - 1653
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2077 KB) |  | HTML iconHTML  

    An optimal strategy for geometric sensor placement to enhance target tracking performance is developed. Recently, a considerable amount of work has been published on optimal conditions for single-update placement of homogeneous sensors (same type and same measurement quality) in which the targets are either assumed perfectly known or the target location uncertainty is averaged out via the expected value of the determinant of the Fisher information matrix (FIM). We derive conditions for optimal placement of heterogeneous sensors based on maximization of the information matrix to be updated by the heterogeneous sensors from an arbitrary Gaussian prior characterizing the uncertainty about the initial target location. The heterogeneous sensors can be of the same or different types (ranging sensors, bearing-only sensors, or both). The sensors can also make, over several time steps, multiple independent measurements of different qualities. Placement strategies are derived and their performance is illustrated via simulation examples. View full abstract»

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  • The Role of Pseudo Measurements in Equality-Constrained State Estimation

    Publication Year: 2013 , Page(s): 1654 - 1666
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3509 KB) |  | HTML iconHTML  

    The pseudo measurement method is a main approach to equality-constrained state estimation due to its simplicity. It is, however, not popular due to possible numerical problems and increased computational complexity. The work presented here further develops the pseudo measurement method. To avoid numerical problems resulting from singular measurement noise when a matrix inverse is used, the Moore-Penrose (MP) inverse is used instead. Also, to reduce the computational load without performance loss and to simplify the analysis of this type of estimation problem, two sequential forms are obtained. They differ only in the processing order of the physical measurement and the pseudo measurement (i.e., the equality constraint). Although form 1 is the same as some existing results, form 2 is new. This motivates the discussion of processing order for this type of estimation problem, especially in the extension to the nonlinear case. It is found that under certain conditions, the use of the pseudo measurement for filtering is redundant. This differs in effect from update by the physically error-free measurement. However, if there exists model mismatch, update by the pseudo measurement is necessary and helpful. Supporting numerical examples are provided. View full abstract»

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  • Input Ripple Current Characteristics of Aviation Static Inverter

    Publication Year: 2013 , Page(s): 1667 - 1676
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5506 KB) |  | HTML iconHTML  

    As a typical load of an aircraft power system, the aviation static inverter (ASI) brings about undesirable low-frequency ripple current on the aeronautic dc bus, which seriously deteriorates the power quality of aeronautic grid. Based on the double-Fourier switching function method, the input current of the inverter unit is analyzed. The corresponding expressions of the dc component, the second harmonic current, the mth harmonic current with regard to the carrier frequency, and the sideband harmonic current are given. In addition the equivalent circuit model of the second harmonic current that spreads to the high-voltage dc bus is derived. This model reveals the generation and propagation characteristics of the low-frequency input ripple current of ASI and its impact factors. Simulation and experimental results are shown to validate the theoretical analysis. View full abstract»

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  • LTP Aggregation of DTN Bundles in Space Communications

    Publication Year: 2013 , Page(s): 1677 - 1691
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3816 KB) |  | HTML iconHTML  

    Delay-/disruption-tolerant networking (DTN) offers a solution to highly stressed communications in space environments. Very little work has been done in investigating how to accommodate highly asymmetric space communication channels for high performance of DTN transmission in space. We study the effect of aggregation of data bundles in space communications characterized by asymmetric and low channel rates and intend to find the number of bundles which should be aggregated within a block for the best performance over highly asymmetric cislunar channel rates. A channel ratio (CR) threshold is derived considering the lengths of an aggregated data block and an acknowledgment (ACK) packet and channel rates, and it must be maintained to avoid delay of ACK transmission of DTN Licklider transmission protocol (LTP) due to space channel asymmetry. View full abstract»

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  • Systematic Bias Correction in Source Localization

    Publication Year: 2013 , Page(s): 1692 - 1709
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8385 KB) |  | HTML iconHTML  

    A novel analytical approach is proposed to approximate and correct the bias in localization problems in n-dimensional space (n = 2 or 3) with N (N >= n) independently usable measurements (such as distance, bearing, time difference of arrival (TDOA), etc.). Here, N is often but not always the same as the number of sensors. This new method mixes Taylor series and Jacobian matrices to determine the bias and leads in the case when N = n to an easily calculated analytical bias expression; however, when N is greater than n, the nature of the calculation is more complicated in that a further step is required. The proposed novel method is generic, which means that it can be applied to different types of measurements. To illustrate this approach we analyze the proposed method in three situations. Monte Carlo simulation results verify that, when the underlying geometry is a good geometry (which allows the location of the target to be obtained with acceptable mean square error (MSE)), the proposed approach can correct the bias effectively in space of dimension 2 or 3 with an arbitrary number of independent usable measurements. In addition the proposed method is applicable irrespective of the type of measurement (range, bearing, TDOA, etc.). View full abstract»

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  • Array Signal Processing via Sparsity-Inducing Representation of the Array Covariance Matrix

    Publication Year: 2013 , Page(s): 1710 - 1724
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2761 KB) |  | HTML iconHTML  

    A method named covariance matrix sparse representation (CMSR) is developed to detect the number and estimate the directions of multiple, simultaneous sources by decomposing the array output covariance matrix under sparsity constraint. In CMSR the covariance matrix elements are aligned to form a new vector, which is then represented on an overcomplete spatial dictionary, and the signal number and directions are finally derived from the representation result. A hard threshold, which is selected according to the perturbation of the covariance elements, is used to tolerate the fitting error between the actual and assumed models. A computation simplification technique is also presented for CMSR in special array geometries when more than one pair of sensors has equal distances, such as the uniform linear array (ULA). Moreover, CMSR is modified with a blind-calibration process under imperfect array calibration to enhance its adaptation to practical applications. Simulation results demonstrate the performance of CMSR. View full abstract»

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  • Data Fusion in MIMO DVB-T-Based Passive Coherent Location

    Publication Year: 2013 , Page(s): 1725 - 1737
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3735 KB) |  | HTML iconHTML  

    Efficient combination of MIMO (multiple-input multiple-output) and PCL (passive coherent location) ideas is expected to improve performance of localization schemes. While, in general, adding the number of transmit and receive antennas provides spatial diversity, it is possible to obtain similar effects by using multiple transmitters that are already transmitting standard signals (such as digital TV (DTV) transmission) in the environment (also known as illuminators of opportunity). However, in the case of passive schemes, it is not always possible to ensure that signals of different transmitters are orthogonal to each other. In such cases in which nonorthogonal transmitter signals are to be used, resolving signals of multiple transmitters reflected from multiple objects is not a trivial problem. One such scenario arises when transmitters of a single frequency network (SFN) are used. Consequently, in order to obtain the desired diversity gain and maintain the correct localization, it is necessary to develop proper techniques to assign each echo that arrives at the receivers to a given transmitter and a specific object that is to be localized. We propose a scheme that addresses the association problem in an efficient way. View full abstract»

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  • A New Method for Loran-C ASF Calculation over Irregular Terrain

    Publication Year: 2013 , Page(s): 1738 - 1744
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5113 KB) |  | HTML iconHTML  

    The finite-difference time-domain (FDTD) method is employed to improve the prediction accuracy of the Loran-C additional secondary factors (ASFs) over irregular terrains. The FDTD method is validated by comparing the results with the theoretical method with flat Earth formula, and then the ASFs are studied as functions of the mountain's slope gradient, height, and width, respectively. The cases with multiple mountains in the propagation paths are also studied. Numerical results show that when the gradient of the mountain is low, the FDTD and integral equation methods both perform well. However, when the gradient of the mountain is rather high, before the mountain area, the FDTD method predicts the ASFs oscillation caused by the reflected and scattered wave from the terrains, whereas the integral equation method is not applicable. Therefore, the FDTD method is better than the integral equation method in predicting Loran-C signals propagating over the region with serious irregularities. The measured ASFs of Loran signals are taken along two real paths between Pucheng and Qinling Mountains in Shaanxi Province, China. It is found that most of the measured and FDTD results have good agreement while some still have certain errors due to the model approximation measured. The ASFs change rapidly in the region with serious irregularities. 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.

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Meet Our Editors

Editor-in-Chief
Lance Kaplan
Army Research Laboratory