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Aerospace and Electronic Systems, IEEE Transactions on

Issue 1 • Date Jan. 1997

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Displaying Results 1 - 25 of 46
  • Target localization from bearings-only observations

    Publication Year: 1997 , Page(s): 2 - 10
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1082 KB)  

    Present a new method for the determination of the distance to a fixed or moving point (or target) from measurements of its direction (or bearing). The article makes none of the usual presumptions concerning random or systematic errors. Rather, it follows a new estimation principle that is designed to deal with both types of errors and allows one to make predictions regarding the "observability" of various aspects of the kinematic state of the target. Numerical examples for the sonar version of the problem are also included. View full abstract»

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  • Data fusion and tracking using HMMs in a distributed sensor network

    Publication Year: 1997 , Page(s): 11 - 28
    Cited by:  Papers (17)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3228 KB)  

    This work deals with the problem of multiple target tracking, from the measurements made on a field of passive sonars activated by an active sonar (multistatic network). The difficulties encountered then are of two kinds: each sensor alone does not provide full observability of a target, and multiple, possibly maneuvering targets moving in a cluttered environment must be dealt with. The algorithm presented here is based on a discrete Markovian modelization of the targets evolution in time. It starts with a fusion of the detections obtained at each measurement time. Tracking and target motion analysis (TMA) are next achieved thanks to dynamic programming (DP). This approach leads to multiple and maneuvering target tracking, with few assumptions; for instance, the use of deterministic target state models are avoided. Simulation results are presented and discussed. View full abstract»

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  • Battery charger design for the Columbus MTFF power system

    Publication Year: 1997 , Page(s): 29 - 37
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3661 KB)  

    A novel pulsewidth-modulated (PWM) dc-dc converter topology is proposed for the battery charge regulator (BCR) of the Columbus Man-Tended Free-Flyer (MTFF) power system. The system is a regulated bus system. Bus voltage control is implemented at the input of the BCR. The use of a conventional buck topology with PWM conductance control at the input results in a second-order behavior. A study of new PWM dc-dc converter topologies has been made to attain a suitable topology. The proposed converter topology is designed and a breadboard including the control loop has been built and tested. The experimental results show that the converter operates according to the design constraints. View full abstract»

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  • A suboptimal algorithm for modulation classification

    Publication Year: 1997 , Page(s): 38 - 45
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1844 KB)  

    In this paper we present a suboptimal algorithm for modulation classification to classify the general M-ary phase-shifted keying (MPSK) signal buried in additive white Gaussian noise (AWGN). We first derive the phase density functions of MPSK signals, then develop the required statistics for modulation classification and demonstrate a classifier for CW, binary phase-shifted keying (BPSK), quadrature phase-shifted keying (QPSK), and 8PSK. The structure of the proposed classifier is flexible and is easy to expand. The performance of classifier is evaluated in terms of the probability of successful classification. An example (BPSK/QPSK case) is provided to demonstrate the capabilities of the proposed classifier. The performance is evaluated through the theoretical approach and the Monte Carlo computer simulations and is compared with that previously published in 1992. It is shown that the performance of the proposed classifier is better. Further improvement in performance can be obtained by increasing the length of observation interval. View full abstract»

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  • Crosslink slot assignment in LEO networks

    Publication Year: 1997 , Page(s): 46 - 52
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3042 KB)  

    The problem of crosslink time slot assignment in low Earth orbiting (LEO) satellite networks is addressed. A crosslink channel connects two neighboring satellites through half-duplexed directional antennas. Coordination among the crosslinks between a satellite and all its neighbors in a dynamic LEO network is a delicate problem and rarely addressed in the literature. The problem is solved here using bipartite graphs. Two versions of slot assignment algorithm are given: distributed and centralized. View full abstract»

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  • Current-fed multiresonant isolated DC-DC converter

    Publication Year: 1997 , Page(s): 53 - 63
    Cited by:  Papers (3)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1796 KB)  

    A novel topology, current-fed multiresonant dc-dc converter (CF-MRC) was studied theoretically and experimentally. The new topology differs from previously described current-fed push-pull parallel-resonant topologies in the fact that the output is coupled to the current of the resonant inductor and in the addition of a second capacitor across the transformer. The main features of the proposed converter are an inherent protection against a short and open circuit at the output, a high voltage gain and zero voltage switching (ZVS) over a large range of output voltage. These characteristics make it a viable choice for applications, such as a high voltage capacitor charger, that require controllable current sourcing over a wide output voltage swing. View full abstract»

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  • Missile autopilot design via functional inversion and time-scaled transformation

    Publication Year: 1997 , Page(s): 64 - 76
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1698 KB)  

    This paper presents a new approach to acceleration control of STT (Skid-To-Turn) missiles. In the design and stability analysis of our autopilot, we assume perfect roll-stabilization but consider fully all other nonlinearities of the missile dynamics including the coupling effect due to bank angle. Our autopilot controller consists of a partial-linearizing controller and a dynamic compensator. The partial-linearizing controller along with a time scaled transformation can convert the nonlinear missile dynamics to the so-called normalized system which is completely independent of Mach number and almost independent of air density. The dynamic compensator is designed based on this normalized system. This normalized system greatly simplifies the design process of an autopilot controller regardless of flight conditions. Our autopilot controller can provide fast and exact set-point tracking performance but without the slow-varying conditions on angle of attack and side-slip angle required often in the prior works. View full abstract»

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  • Variable structure robust flight control system for the F-14

    Publication Year: 1997 , Page(s): 77 - 84
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1454 KB)  

    In this paper, a flight control law for a simplified F-14 aircraft model is designed based on variable structure control (VSC) theory. For m-input, q-output linear uncertain systems (q View full abstract»

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  • A new distributed constant false alarm rate detector

    Publication Year: 1997 , Page(s): 85 - 97
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2704 KB)  

    A new constant false alarm rate (CFAR) test termed signal-plus-order statistic CFAR (S+OS) using distributed sensors is developed. The sensor modeling assumes that the returns of the test cells of different sensors are all independent and identically distributed In the S+OS scheme, each sensor transmits its test sample and a designated order statistic of its surrounding observations to the fusion center. At the fusion center, the sum of the samples of the test cells is compared with a constant multiplied by a function of the order statistics. For a two-sensor network, the functions considered are the minimum of the order statistics (mOS) and the maximum of the order statistics (MOS). For detecting a Rayleigh fluctuating target in Gaussian noise, closed-form expressions for the false alarm and detection probabilities are obtained. The numerical results indicate that the performance of the MOS detector is very close to that of a centralized OS-CFAR and it performs considerably better than the OS-CFAR detector with the AND or the OR fusion rule. Extension to an N-sensor network is also considered, and general equations for the false alarm probabilities under homogeneous and nonhomogeneous background noise are presented. View full abstract»

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  • Dielectric lens antenna with scan reflector

    Publication Year: 1997 , Page(s): 98 - 101
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (964 KB)  

    A dielectric lens antenna with a scanning reflector that is coaxial to the lens is described, and its aberrations are analyzed. The result shows that aberrations of the system will deteriorate severely when a planar reflector is used, but the aberrations can be significantly reduced when a corrected phase reflector is used. View full abstract»

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  • Effects of polarization and resolution on SAR ATR

    Publication Year: 1997 , Page(s): 102 - 116
    Cited by:  Papers (49)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (14867 KB)  

    Lincoln Laboratory is investigating the detection and classification of stationary ground targets using high resolution, fully polarimetric, synthetic aperture radar (SAR) imagery. A study is summarized in which data collected by the Lincoln Laboratory 33 GHz SAR were used to perform a comprehensive comparison of automatic target recognition (ATR) performance for several polarization/resolution combinations. The Lincoln Laboratory baseline ATR algorithm suite was used, and was optimized for each polarization/resolution case. Both the HH polarization alone and the optimal combination of HH, HV, and VV were evaluated; the resolutions evaluated were 1 ft×1 ft and 1 m×1 m. The data set used for this study contained approximately 74 km2 of clutter (56 km2 of mixed clutter plus 18 km2 of highly cultural clutter) and 136 tactical target images (divided equally between tanks and howitzers). View full abstract»

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  • Eigen-decomposition techniques for Loran-C skywave estimation

    Publication Year: 1997 , Page(s): 117 - 125
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (958 KB)  

    Eigen-decomposition spectral analysis techniques are used to estimate the delays of Loran-C skywaves. Their performance is evaluated and compared with that of Fourier-based techniques. Results using off-air data are presented. This work establishes the basis on which to design a Loran-C receiver capable of adjusting its sampling point adaptively to the optimal value in a constantly changing skywave environment. Such receivers promise to improve significantly the accuracy and reliability of positioning under adverse operational conditions. View full abstract»

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  • Uncertainty ellipses and their application to interval estimation of emitter position

    Publication Year: 1997 , Page(s): 126 - 133
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1640 KB)  

    A method of interval estimation of position of an object emitting electromagnetic energy is presented. The problem is considered in cases of known and unknown errors of emitter position determination. Precise expressions concerning two-dimensional confidence regions for unknown position of the emitter have been obtained. Uncertainty regions defined as error ellipses and confidence ellipses have been determined. Qualitative and quantitative comparison of considered regions have been made. The presented approach and obtained results may be useful in electronic intelligence (ELINT) and electronic warfare (EW) applications, in radio navigation, ballistics, and in rescue operations at sea as well. View full abstract»

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  • High-efficiency Loran-C interference identification by synchronous sampling

    Publication Year: 1997 , Page(s): 134 - 141
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1388 KB)  

    A new technique is proposed for estimating the frequencies within carrier-wave interference (CWI) affecting Loran-C receivers. Its novelty lies in that interference samples are taken synchronously with the Loran-C pulses and ensemble-averaged in the time domain prior to conventional spectrum analysis. Each interferer is thus automatically weighted according to its effect on the phase tracking operation of the receiver. The new method substantially increases the efficiency with which the most insidious interferers may be pinpointed. It requires little additional computational power or memory in the receiver. View full abstract»

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  • CFE-SS approach for salient-pole synchronous generators under unbalances

    Publication Year: 1997 , Page(s): 142 - 162
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8835 KB)  

    A time-stepping coupled finite element-state space approach was developed for synchronous machine unbalanced impedance load and balanced/unbalanced rectifier load operation, in the natural time-domain ABC frame of reference. Synergism between the space and time harmonics was inherently included in the simulated results by use of this approach. It offers an effective and powerful tool for synchronous machine design before prototype construction. View full abstract»

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  • Analysis of a PWM-resonant converter

    Publication Year: 1997 , Page(s): 163 - 170
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2444 KB)  

    When a parallel resonant tank is excited by a bipolar current pulse train a sinusoidal voltage develops across the tank whose amplitude depends on the duty cycle of the pulse train. An isolated secondary can be derived by applying the tank voltage to an isolation transformer whose magnetizing inductance acts as the resonant inductor of the tank circuit. A dc output voltage is obtained after rectification and filtering of the sinusoidal secondary voltage and regulation is achieved by controlling the duty cycle of the pulse train. The sinusoidal nature of the voltage across the isolation transformer alleviates some of the noise problem associated with parasitic capacitances of an isolation transformer when operated with square voltage waveform. In this work the dc and small-signal analysis of the converter is given and an equivalent small-signal circuit model is derived. Experimental results which confirm the validity of the model are presented. View full abstract»

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  • Digital tracking filters with high order correlated measurement noise

    Publication Year: 1997 , Page(s): 171 - 177
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (569 KB)  

    The existing algorithms for the design of digital filters with colored measurement noise involve a restriction on the dimension of the measurement error model. Kalman filter equations and state space partition are used to formulate an optimal tracking filter without such restrictions. The input to the new filter are two consecutive measurements, and it is initialized by using the first available measurements and the error model correlation matrix. Several examples illustrate the filter formulation and initialization. View full abstract»

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  • Discrete-time observability and estimability analysis for bearings-only target motion analysis

    Publication Year: 1997 , Page(s): 178 - 201
    Cited by:  Papers (27)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2134 KB)  

    Observability in the context of bearings-only tracking (BOT) is still the subject of important literature. Different from previous approaches, where continuous-time analysis was considered, our approach relies on discrete-time analysis. It is then shown that this allows us to use directly and efficiently the simple formalisms of linear algebra. Using the direct approach, observability analysis is essentially reduced to basic considerations about subspace dimensions. Even if this approach is conceptually quite direct, it becomes more and more complex as the source-encounter scenario complexity increases. For complex scenarios, the dual approach may present some advantages essentially due to the direct use of multilinear algebra. New results about BOT observability for maneuvering sources are thus obtained. Observability analysis is then extended to unknown instants of source velocity changes. Even if observability analysis provides thorough insights about the algebraic structure of the BOT problem, the optimization of the observer maneuvers is essentially a control problem. Basic algebraic considerations prove that a relevant cost functional for this control problem is the determinant of the Fisher information matrix (FIM). So, a large part of this work is devoted to the analysis of this cost functional. Using multilinear algebra, general approximations of this functional are given. In order to involve only directly estimable parameters, the source bearing-rates are examined. Using these approximations, a general framework for optimizing the observer trajectory is derived which allow us to approximate the optimal sequence of controls. It is worth stressing that our approach does not require the knowledge of the source trajectory parameters and is still valid for a maneuvering source. View full abstract»

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  • A grid algorithm for autonomous star identification

    Publication Year: 1997 , Page(s): 202 - 213
    Cited by:  Papers (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2110 KB)  

    An autonomous star identification algorithm is described that is simple and requires less computer resources than other such algorithms. In simulations using an 8×8 degree field of view (FOV), the algorithm identifies the correct section of sky on 99.7% of the sensor orientations where spatial accuracy of the imaged star is 1 pixel (56.25 arc seconds) in standard deviation and the apparent brightness deviates by 0.4 units stellar magnitude. This compares very favorably with other algorithms in the literature. View full abstract»

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  • A strapdown inertial navigation system for the flat-Earth model

    Publication Year: 1997 , Page(s): 214 - 224
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (913 KB)  

    The development of a strapdown inertial navigation system (SINS) for aerodynamically controlled vehicles, which are limited to altitudes below 30 km (that is, a small distance compared with the Earth's radius of about 7000 km), or using the so-called flat-Earth model (FEM), is the principal objective of this work. In dealing with the FEM equations, the north, east, down (NED) frame on the surface of the Earth is taken as an inertial reference frame. Although, this frame is both accelerating and rotating, the accelerations associated with the Earth's rotation are negligible compared with the acceleration that can be produced by a maneuvering aircraft. Also, in this model, the gravity is taken as constant. In developing the SINS for the FEM, the aerodynamic force and moment have dominant roles, depending primarily on such variables as the angle of attack and sideslip, their derivatives, components of the angular velocity of the aircraft, and the control inputs. On the other hand, the SINS deals with such variables as the small-angle rotation vectors. Thus, it was necessary to link both set of variables as state variables of the strapdown FEM as is done in this work. The developed model is relevant for small (less than 200) angles of attack and sideslip. View full abstract»

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  • Performance of a two-layer LEO satellite communication network

    Publication Year: 1997 , Page(s): 225 - 231
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3007 KB)  

    A novel two-layer low Earth orbiting (LEO) satellite network is proposed. Comparing with a single layer global network, not only the system performance is improved but also the number of satellites can be reduced. The main ideas include (1) to raise the altitude of the original global network, and (2) to add several satellites at lower altitude to form a regional network to serve calls from the areas of heavy traffic. In order to fully utilize the benefits of the two-layer network, additional functions such as adjustable beam and dynamic channel management are added. Call blocking rate is derived. Numerical examples are provided to demonstrate several interesting phenomena. View full abstract»

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  • Tracking an incoming ballistic missile using an extended interval Kalman filter

    Publication Year: 1997 , Page(s): 232 - 240
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1570 KB)  

    The important tracking problem by radar of an incoming ballistic missile system, which contains uncertainty in modeling and noise in both dynamics and measurements, is studied. The classical extended Kalman filter (EKF) is no longer applicable to such an uncertain system, and so a new extended interval Kalman filter (EIKF) is developed for tracking the missile system. Computer simulation is presented to show the effectiveness of the EIKF algorithm for this uncertain and nonlinear ballistic missile tracking problem. View full abstract»

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  • Comparison of signal estimation using calibrated and uncalibrated arrays

    Publication Year: 1997 , Page(s): 241 - 249
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1373 KB)  

    We consider the problem of separating and estimating the waveform of superimposed signals received by an array of sensors. If the array is well calibrated it is possible to first estimate the directions of arrival (DOA) of the signals and then use this information to separate the signals. When the array is not calibrated, but the array elements have the same unknown gain pattern, up to an unknown multiplicative factor and the phases of the elements are arbitrary and unknown, it is possible to estimate the array steering vectors and then use this information for signal estimation. We compare the quality of the estimated signals in the calibrated case with the quality of the estimated signals in the uncalibrated case, in terms of the output signal-to-interference ratio (SIRO) and output signal-to-noise ratio (SNRO). View full abstract»

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  • Interval Kalman filtering

    Publication Year: 1997 , Page(s): 250 - 259
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1531 KB)  

    The classical Kalman filtering technique is extended to interval linear systems with the same statistical assumptions on noise, for which the classical technique is no longer applicable. Necessary interval analysis, particularly the notion of interval expectation, is reviewed and introduced. The interval Kalman filter (IKF) is then derived, which has the same structure as the classical algorithm, using no additional analysis or computation from such as H-mathematics. A suboptimal IKF is suggested next, for the purpose of real-time implementation. Finally, computer simulations are shown to compare the new interval Kalman filtering algorithm with the classical Kalman filtering scheme and some other existing robust Kalman filtering methods. View full abstract»

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  • Nonlinear filtering methods application in INS alignment

    Publication Year: 1997 , Page(s): 260 - 272
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2105 KB)  

    The problem of course alignment of inertial navigation systems is considered. Error equations of nonlinear character have been obtained at a considerable level of a priori course uncertainty. The algorithm for solving the problem of optimal estimation of the state vector described by nonlinear equations from linear measurements has been developed for the analysis of a potential alignment accuracy with the piecewise-Gaussian approximation of a posteriori density used. The results of the study of efficiency of various suboptimal alignment algorithms obtained by the use of the software developed are presented and discussed. 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