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Aerospace and Electronic Systems, IEEE Transactions on

Issue 2 • Date April 2004

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Displaying Results 1 - 25 of 36
  • Real-time translational control of a MEMS comb resonator

    Page(s): 567 - 575
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2161 KB) |  | HTML iconHTML  

    Closed-loop control has been successfully applied to a microelectromechanical systems (MEMS) lateral comb resonator device in real-time to perform impulse disturbance damping and sinusoidal position control, enabled by the use of a through-wafer optical microprobe to obtain position feedback. This result leverages the application of lifetime, in-situ control of MEMS in order to provide quality assurance of microsystems in safety critical applications. A position feedback signal produced by a through-wafer optical microprobe has been used for comb resonator system model identification by two independent methods to accurately determine the effective mass, damping, and spring constant values of the device. After accurate determination of system parameters, closed-loop impulse disturbance damping and proportional-integral-differential (PID) translational control were applied. Closed-loop control results presented indicate controllability of such microstructures and response times on the order of the natural frequency of the device. View full abstract»

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  • Polarization diversity detection of distributed targets in compound-Gaussian clutter

    Page(s): 755 - 765
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (397 KB)  

    We deal with the problem of polarimetric detection of compound-Gaussian clutter with unknown distributed targets in covariance matrix. Since no uniformly most powerful (UMP) detector exists for the problem at hand, we devise and assess two classes of suboptimum receivers. The former contains two detectors, designed according to the Wald and the generalized likelihood ratio tests, which resort to secondary data, free of signal components and with the same covariance structure of the cells under test, for estimating the clutter spectral properties. The latter contains a detector which achieves adaptivity without exploiting the training set All the decision rules ensure the constant false alarm rate (CFAR) property with respect to the texture statistics but they are not theoretically CFAR with respect to the disturbance covariance matrix. Finally, we present simulation results, based also on real clutter data, showing that the Wald test receiver achieves in general a better detection performance and a stronger robustness than its counterparts. View full abstract»

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  • Exact multisensor dynamic bias estimation with local tracks

    Page(s): 576 - 590
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (791 KB) |  | HTML iconHTML  

    An exact solution is provided for the multiple sensor bias estimation problem based on local tracks. It is shown that the sensor bias estimates can be obtained dynamically using the outputs of the local (biased) state estimators. This is accomplished by manipulating the local state estimates such that they yield pseudomeasurements of the sensor biases with additive noises that are zero-mean, white, and with easily calculated covariances. These results allow evaluation of the Cramer-Rao lower bound (CRLB) on the covariance of the sensor bias estimates, i.e., a quantification of the available information about the sensor biases in any scenario. Monte Carlo simulations show that this method has significant improvement in performance with reduced rms errors of 70% compared with commonly used decoupled Kalman filter. Furthermore, the new method is shown to be statistically efficient, i.e., it meets the CRLB. The extension of the new technique for dynamically varying sensor biases is also presented. View full abstract»

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  • Design of multi-sensor attitude determination systems

    Page(s): 627 - 649
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1757 KB) |  | HTML iconHTML  

    The design of inexpensive multi-sensor attitude determination systems is discussed. The systems discussed fuse information from a triad of solid state rate gyros with an aiding system mechanized using GPS or magnetometers and accelerometers. Euler angle and quaternion-based sensor fusion algorithms are developed. Methods for gain scheduling and estimator pole placement are presented. Using simulation and flight test results, it is shown that quaternion-based algorithms simplify gain scheduling and improve transient response. View full abstract»

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  • Fuzzy corrections in a GPS/INS hybrid navigation system

    Page(s): 591 - 600
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (841 KB) |  | HTML iconHTML  

    A new concept regarding GPS/INS integration, based on artificial intelligence, i.e. adaptive neuro-fuzzy inference system (ANFIS) is presented. The GPS is used as reference during the time it is available. The data from GPS and inertial navigation system (INS) are used to build a structured knowledge base consisting of behavior of the INS in some special scenarios of vehicle motion. With the same data, the proposed fuzzy system is trained to obtain the corrected navigation data. In the absence of the GPS information, the system will perform its task only with the data from INS and with the fuzzy correction algorithm. This paper shows, using Matlab simulations, that as long as the GPS unavailability time is no longer than the previous training time and for the scenarios a priori defined, the accuracy of trained ANFIS, in absence of data from a reference navigation system, is better than the accuracy of stand-alone INS. The flexibility of model is also analyzed. View full abstract»

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  • From the editors

    Page(s): 385
    Save to Project icon | Request Permissions | PDF file iconPDF (191 KB)  
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  • On joint track initiation and parameter estimation under measurement origin uncertainty

    Page(s): 675 - 694
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (898 KB) |  | HTML iconHTML  

    The problem of joint detection and estimation for track initiation under measurement origin uncertainty is studied. The two well-known approaches, namely the maximum likelihood estimator with probabilistic data association (ML-PDA) and the multiple hypotheses tracking (MHT) via multiframe assignment, are characterized as special cases of the generalized likelihood ratio test (GLRT) and their performance limits indicated. A new detection scheme based on the optimal gating is proposed and the associated parameter estimation scheme modified within the ML-PDA framework. A simplified example shows the effectiveness of the new algorithm in detection performance under heavy clutter. Extension of the results to state estimation with measurement origin uncertainty is also discussed with emphasis on joint detection and recursive state estimation. View full abstract»

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  • Ground-multi path mitigation via polarization steering of GPS signal

    Page(s): 536 - 552
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1611 KB) |  | HTML iconHTML  

    Multipath (MP) is the dominant error source in Global Positioning System (GPS) code-based position solutions requiring high accuracy. A technique is introduced here to mitigate error due to ground-reflected MP signals. The technique uses two orthogonal dipoles to capture the direct GPS signal and the ground-reflected GPS signal. Adjusting the amplitude and phase of the received voltage between the two dipoles can reduce the impact of MP error. Theoretical derivations of this technique are performed for a GPS signal upon reflection from dry soil, seawater, and fresh water. The theoretical results are verified with a real world experiment on the aforementioned surfaces. GPS pseudo-range (PR) and carrier-to-noise ratio (C/No) measurements for specific satellites are used to verify the predicted theoretical results. View full abstract»

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  • ZCS-PWM boost rectifier with high power factor and low conduction losses

    Page(s): 650 - 660
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1134 KB) |  | HTML iconHTML  

    A new single-phase high power factor rectifier is proposed, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current-switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the switches and zero-voltage-switching (ZVS) in the diodes. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM switch model is used to predict the system performance. A prototype rated at 1 kW, operating 60 kHz, with an input ac voltage of 220 Vrms and an output voltage 400 Vdc has been implemented in laboratory. An efficiency of 97.2% and power factor near 0.99 has been measured. The analysis and design of the control circuitry are also presented. View full abstract»

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  • Tolerance design of controllers for switching regulators

    Page(s): 661 - 674
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (897 KB) |  | HTML iconHTML  

    An evolutionary approach to worst case tolerance design is introduced here, with a focus on feedback compensation networks for dc-dc switching converters. Assumed that varying parameters values are uniformly distributed and uncorrelated, as provided by the worst case approach, the proposed algorithm, of general applicability, seeks for the set of nominal values and tolerances of the circuit parameters ensuring that the design constraints are met and that a user-defined circuit performance index assumes its optimal value. Design constraints, are fixed in the frequency domain, in terms of acceptability ranges of loop gain crossover frequency and phase margin, to guarantee closed loop stability and the desired dynamic performance. Resistive and capacitive compensation network's parameters values are chosen within a suitable database of couples nominal value/tolerance available on the market, while the nominal values and tolerances of the parameters of the power stage are fixed. Referring to a buck dc-dc switching regulator, two widely used different compensation network topologies are compared in terms of reliability, robustness, and cost of components. Simulation results show the wide usefulness of the proposed method in supporting designer decisions. View full abstract»

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  • Design considerations for a real-time random-noise tracking radar

    Page(s): 434 - 445
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (883 KB) |  | HTML iconHTML  

    Random-noise radar has been applied successfully to range measurement, velocity estimation and terrain/target imaging. For applications involving stationary targets, long integration times and process averaging are easily tolerated. In situations where the target or radar platform moves at high speed, the impact of this relative motion on system design should be considered. This work addresses the statistical performance of a generic random-noise radar receiver and examines the inter-relationships between design parameters and performance tradeoffs. Complementing this examination, a random-noise monopulse system is also investigated as a possible architecture for real-time angle estimation. Simulations and numerical illustrations provide the basis of processor design and performance prediction. View full abstract»

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  • Space vector modulation strategy for an eight-switch three-phase NPC converter

    Page(s): 553 - 566
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1044 KB) |  | HTML iconHTML  

    A three-phase neutral point clamped (NPC) converter is presented for power factor correction and dc-link voltage regulation. A simplified space vector pulsewidth modulation scheme (SVPWM) is adopted to track line current commands. Using a simplified SVPWM algorithm, the calculated time for the time duration of voltage vector is reduced. The adopted NPC converter has less power switches compared with the conventional three-level NPC converter. Only eight power switches and four clamping diodes with voltage stress of half the dc bus voltage are used in the circuit configuration. Based on the proposed control algorithm, a reference voltage vector is generated on the ac terminal for drawing the sinusoidal line currents with unity power factor. Computer simulation and experimental results based on a laboratory prototype are presented to verify the validity and effectiveness of the proposed control strategy. View full abstract»

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  • Flight-test results of an integrated wideband-only airport pseudolite for the category II/III local area augmentation system

    Page(s): 734 - 741
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    The results of a flight test are presented that successfully demonstrate the integration of a wideband-only airport pseudolite (WBAPL) into a prototype local area augmentation system (LAAS). An analysis of the error performance exhibited by the prototype LAAS, with and without the inclusion of the WBAPL in the system, is presented. The inclusion of the WBAPL is shown to not only increase the availability of the system, but also to improve its error performance. The improvement in performance is seen to be most pronounced when a reduced GPS SV set is available, a state that would otherwise result in the unavailability of LAAS. This is the first demonstration of simultaneous increase in availability and accuracy from the inclusion or a WBAPL into a prototype LAAS. View full abstract»

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  • Waveform fusion in sonar signal processing

    Page(s): 462 - 477
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1033 KB) |  | HTML iconHTML  

    In active sonar systems, proper selection of the transmitted waveform is critical for target detection and parameter estimation, especially with the existence of clutter (reverberation). Two commonly used waveforms (constant frequency (CF) and linear frequency modulated (LFM)) are studied. Their characteristics are complementary both with respect to their accuracies and their sensitivity to the blind zero-Doppler ridge. Several fusion schemes of the two kinds of waveforms are explored and fusion results are studied both analytically and from simulation. It is concluded that fusion of the information of different waveforms can be not only more robust, but in some cases outright preferable, in term of detection probability and estimation accuracy. View full abstract»

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  • Multisensor resource deployment using posterior Cramer-Rao bounds

    Page(s): 399 - 416
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (958 KB) |  | HTML iconHTML  

    The development of a general framework for the systematic management of multiple sensors in target tracking in the presence of clutter is described. The basis of the technique is to quantify, and subsequently control, the accuracy of target state estimation. The posterior Cramer-Rao lower bound (PCRLB) provides the means of achieving this aim by enabling us to determine a bound on the performance of all unbiased estimators of the unknown target state. The general approach is then to use optimization techniques to control the measurement process in order to achieve accurate target state estimation. We are concerned primarily with the deployment and utilization of limited sensor resources. We also allow for measurement origin uncertainty, with sensor measurements either target-generated or false alarms. An example in which the aim is to track a submarine by deploying a series of constant false-alarm rate passive sonobuoys is presented. We show that by making some standard assumptions, the effect of the measurement origin uncertainty can be expressed as a state-dependent information reduction factor which can be calculated off-line. This enables the Fisher information matrix (FIM) to be calculated quickly, allowing Cramer-Rao bounds to be utilized for real-time, dynamic sensor management. The sensor management framework is shown to determine deployment strategies that enable the target to be accurately localized, and at the same time efficiently utilize the limited sensor resources. View full abstract»

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  • Binary integration with a cascaded detection scheme

    Page(s): 751 - 755
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (306 KB)  

    Methods for evaluating the probability of detection for binary integration have been extended to the case of a cascaded detection scheme where the inputs to the binary detector are no longer single pulse outputs but the outputs of a noncoherent integration detector. Swerling II and IV expressions are easily generalized by simply redefining the p term in the cumulative binomial probability to represent the probability of detection associated with the noncoherent detector output. The Swerling I and III cases are somewhat more complicated. For these latter cases we have developed a numerical technique that we have named "piecewise linear integration". With this technique we have the means to evaluate the relevant detection probabilities, and we can compare two alternative ways of Implementing RF diversity for the cascaded detector above. View full abstract»

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  • In-orbit demonstration of rendezvous laser radar for unmanned autonomous rendezvous docking

    Page(s): 617 - 626
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1513 KB) |  | HTML iconHTML  

    The National Space Development Agency of Japan (NASDA) performed unmanned autonomous rendezvous docking (RVD) experiments using the Engineering Test Satellite VII (ETS-VII) in 1998 and 1999. In these experiments, a rendezvous laser radar (RVR) was used as the primary navigation sensor during the final approach phase (relative distances from 500 m to 2 m). The RVR functioned properly, and its characteristics, which are measurement accuracy, optical propagation, and acquisition/tracking, satisfied the requirements. The experimental results show that RVR is effective for autonomous rendezvous docking. View full abstract»

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  • Multibaseline ATI-SAR for robust ocean surface velocity estimation

    Page(s): 417 - 433
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (807 KB) |  | HTML iconHTML  

    An open problem of along-track interferometry (ATI) for synthetic aperture radar (SAR) sensing of ocean surface currents is the need of ancillary wind information for inversion of Doppler centroid measurements, that have to be compensated for the propagation velocity of advancing and/or receding Bragg scatterers. We propose three classes of estimators which exploit multibaseline (MB) ATI acquisition and Doppler resolution for robust data inversion under different degrees of a priori information about the wind direction and the value of the characteristic Bragg frequency. Performance analysis and comparison with conventional ATI show that the proposed MB estimators can produce accurate velocity estimates in the absence of detailed ancillary data. View full abstract»

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  • Equal allocation scheduling for data intensive applications

    Page(s): 695 - 705
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (651 KB) |  | HTML iconHTML  

    A new analytical model for equal allocation of divisible computation and communication load is developed. Equal allocation of load is attractive in multiple processor systems when real time information on processor and link capacity that is necessary for optimal scheduling is not available. The model includes a detailed accounting of solution reporting time. Equal allocation scheduling is compared with sequential scheduling and a new type of multi-installment scheduling. Aerospace applications include the processing of satellite imagery, radar, and sensor networks. View full abstract»

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  • Observability of an integrated GPS/INS during maneuvers

    Page(s): 526 - 535
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (733 KB) |  | HTML iconHTML  

    An observability analysis of a GPS/INS system during manoeuvers is presented based upon a perturbation model with respect to the Earth-centered-Earth-fixed (ECEF) coordinate system. Analysis is performed on two types of manoeuvers, linear acceleration and steady turn. These manoeuvers could be used for in-flight INS alignment using GPS. During the constant linear acceleration without rotation relative to the Earth, the linear system model is shown to be time-invariant. The observability analysis for the time invariant linear system model shows that linear acceleration does not change the number of observable modes but rather the structure of the observable space. For a nonconstant linear acceleration or a steady turn, the perturbation linear system becomes time varying. For this time-varying system, three types of observability are considered, complete, differential, and instantaneous observability. Instantaneous observability is the strongest properties and means that the state of the system at any time may be determined instantaneously from observation of the output and its derivatives. Instantaneous observability is important for fast in-flight INS alignment. It is shown that the number of instantaneously observable moded is increased by at least 2 during a maneuver. Hence, some linear combinations of the attitude angles become instantaneously observable. View full abstract»

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  • Search using multiple UAVs with flight time constraints

    Page(s): 491 - 509
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2799 KB) |  | HTML iconHTML  

    We consider a large scale system consisting of multiple unmanned aerial vehicles (UAVs) performing a search and surveillance task, based on the uncertainty map of an unknown region. The search algorithm is based on the k-shortest path algorithm that maximizes the effectiveness of the search in term of searching through the maximum uncertainty region, given a constraint on the endurance time of the UAV and on the location of the base station from which the UAVs operate. These constraints set apart this class of problems from the usual search and surveillance problems. We compare the performance of this algorithm with a random search and a greedy strategy search, We also implement the algorithm for the case of multiple UAVs searching an unknown region. The cases of delayed and partial information are also considered. Simulation results that demonstrate the efficacy of the technique are also presented. View full abstract»

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  • Recursive estimation of radar biases using electronic charts

    Page(s): 725 - 734
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1073 KB)  

    This work describes the application of the extended Kalman filter (EKF) to the estimation of range and bearing biases in marine radars by performing a map-matching between the data from hydrographic charts and the radar images. By defining at least two corresponding points from the radar image and the electronic charts, the technique provides a rapid and accurate calibration in range and bearing, giving also estimates for the speed, heading, latitude, and longitude of the ship. The method is tested with simulated data to check convergence and later with real data obtained from a navigation console installed on a patrol boat The technique does not require GPS nor speed information from the ship log unit, however it is shown that their inclusion can improve the estimation. View full abstract»

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  • Reduced state estimator for systems with parametric inputs

    Page(s): 446 - 461
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (752 KB) |  | HTML iconHTML  

    A reduced state estimator is derived for systems with bounded parameters as inputs. Optimal filter gains are derived for minimizing the total covariance of the estimation error due to measurement noise and parameter uncertainty. It is shown that these filter gains for a two-state system with a Gaussian parameter satisfy the Kalata relation in steady state. Equations are also derived for optimally filtering measurements in arbitrary time order. This reduced state estimator offers novelties over a traditional Kalman filter in its application to the class of problems considered. The total error covariance, which is minimized, makes no use of plant noise. Furthermore, the filter is easier to optimize in high dimensional and multiple sensor applications as well as in processing out-of-sequence measurements. View full abstract»

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  • Adaptive controller design for a linear motor control system

    Page(s): 601 - 616
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1004 KB) |  | HTML iconHTML  

    Three different adaptive controllers for a permanent magnet linear synchronous motor (PMLSM) position-control system are proposed. The proposed controllers include: a backstepping adaptive controller, a self-tuning adaptive controller, and a model reference adaptive controller. The detailed systematic controller design procedures are discussed. A PC-based position control system is implemented. Several experimental results including transient responses, load disturbance responses, and tracking responses of square-wave, sinusoidal-wave, and triangular-wave commands are discussed and compared. The proposed system has a good robustness performance even though the inertia of the system is increased to 10 times. The experimental results validate the theoretical analysis. View full abstract»

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  • Clutter map information for data association and track initialization

    Page(s): 387 - 398
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB) |  | HTML iconHTML  

    This paper considers the problem of forming and maintaining tracks when measurements have both uncertain origin and are corrupted by additive sensor noise. The spatial clutter measurement density is assumed nonhomogeneous and known. The PPDA-MAP algorithm provides a set of recursive formulae for data association and probability of target existence, thus enabling automatic track initiation, track maintenance, and track termination. New values for initial probability of target existence for IPDA-type algorithm are also derived. Simulation results compare the performance of IPDA-MAP with IPDA, IMM-PDA, IMM-PDA-MAP, EB-PDA and EB-PDA-MAP in a heavy and nonuniform clutter situation. 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