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Aerospace and Electronic Systems, IEEE Transactions on

Issue 1 • Date Jan. 1999

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Displaying Results 1 - 25 of 36
  • Comments on "Bearings-only and Doppler-bearing tracking using instrumental variables"

    Page(s): 370 - 371
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (166 KB)  

    The work carried out by Y.T. Chan and S.W. Rudnicki [ibid., vol. 28, pp. 1076-82, 1992] is very useful for studies in underwater target motion analysis. They presented a simple procedure so that the dimension of the target state vector need not be increased. While implementing their work, I tried to rederive the equations and found that there is a confusion in one of the equations, which I discuss here. View full abstract»

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  • Call for papers

    Page(s): 380
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    Freely Available from IEEE
  • Position fix from three GPS satellites and altitude: a direct method

    Page(s): 350 - 354
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    A method to find a direct solution to GPS equations given four pseudo-range measurements and satellite positions is given by L.O. Krause [1987]. This method is modified here to find a direct solution given three pseudo-ranges and satellite positions and altitude above the reference ellipsoid View full abstract»

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  • Multiparametric importance sampling for simulation of radar systems

    Page(s): 123 - 137
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    The performances of the importance sampling (IS) techniques are improved by using multiparametric distortions of the input random processes. The analysis of different constant false-alarm rate (CFAR) algorithms confirms the usefulness of this method. The potential of this new approach is fully exploited if optimization techniques are used to obtain the optimum distortions and to avoid bias in the estimates View full abstract»

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  • 3D guidance law modeling

    Page(s): 72 - 83
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1064 KB)  

    Proportional navigation (PN) guidance laws (GLs) have been widely used and studied in the guidance literature. But most of the guidance literature on PN has concentrated on the evaluation of empirical PNGLs or GLs obtained from very specific optimality considerations. The authors present a novel approach (called guidance laws modeling) to derive new GLs. They consider the basic requirements of capture and define a complete class of GLs that meet these requirements. It is shown that PN is a natural candidate in this class. The main consequence of this modeling process is the definition of two new GLs: one in 2D space and the other in 3D space. These new GLs can be interpreted as new generalizations of the true proportional navigation (TPN) GL. Moreover, it is shown that these generalizations allow the TPNGL to match the capturability performance of the pure proportional navigation (PPN) GL in terms of initial conditions which allow the guided object to reach its target View full abstract»

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  • Decimating pseudorandom noise receiver

    Page(s): 338 - 343
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    A pseudorandom noise (PN) coded CW radar with a novel decimating digital correlator is discussed. The motivation for using this decimation technique is to reduce the analog-to-digital (A/D) sampling rate and corresponding digital signal processing (DSP) rates. This provides the radar designer the ability to improve the range resolution of the radar beyond the current capabilities of A/D and DSP hardware. This new decimating digital correlation technique is based on existing theories of decimating PN sequences. The fundamental principles of this decimating digital correlator design are presented and simulation results are provided to demonstrate feasibility View full abstract»

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  • Super resolution SAR imaging via parametric spectral estimation methods

    Page(s): 267 - 281
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    Super resolution synthetic aperture radar (SAR) image formation via sophisticated parametric spectral estimation algorithms is considered. Parametric spectral estimation methods are devised based on parametric data models and are used to estimate the model parameters. Since SAR images rather than model parameters are often used in SAR applications, we use the parameter estimates obtained with the parametric methods to simulate data matrices of large dimensions and then use the fast Fourier transform (FFT) methods on them to generate SAR images with super resolution. Experimental examples using the MSTAR and Environmental Research Institute of Michigan (ERIM) data illustrate that robust spectral estimation algorithms can generate SAR images of higher resolution than the conventional FFT methods and enhance the dominant target features View full abstract»

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  • Transmitter model for the design of communication satellites

    Page(s): 31 - 42
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    The paper proposes a modeling approach for satellite communication systems able to relate analytically the on-board transmitter reliability to the effective isotropic radiated-power (EIRP) requirement. The latter, in fact, plays a key role in system design, yielding a direct impact on transmitter configuration and technological features. In addition, that requirement is directly related to the antenna characteristics and, hence, to the critical compromise between transmitter and antenna specifications. In this frame, the proposed model, which is based on an innovative design-oriented approach, is able to relate the antenna complexity to the transmitter reliability and, therefore, to the overall system reliability. The potential of the proposed approach is pointed our through the description of the analytical model and the achieved results View full abstract»

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  • Optimization of multiframe target detection schemes

    Page(s): 176 - 187
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    We optimize the performance of multiframe target detection (MFTD) schemes under extended Neyman-Pearson (NP) criteria. Beyond the per-track detection performance for a specific target path in conventional MFTD studies, we optimize the overall detection performance which is averaged over all the potential target paths. It is shown that the overall MFTD performance is limited by the mobility of a target and also that optimality of MFTD performance depends on how fully one ran exploit the information about the target dynamics. We assume a single target situation and then present systematic optimization by formulating the MFTD problems as binary composite hypotheses testing problems. The resulting optimal solutions suggest computationally efficient implementation algorithms which are similar to the Viterbi algorithm for trellis search. The optimal performances for some typical types of target dynamics are evaluated via Monte-Carlo simulation View full abstract»

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  • Dynamic modeling of flexible multibody structures

    Page(s): 148 - 156
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (652 KB)  

    This work is primarily concerned with the development of a mathematical formulation capable of treating the problems of maneuvering and control of flexible multibody structures. The analytical formulation is based upon equations of motion in terms of quasi-coordinates derived for each substructure independently. The individual substructures are made to act as a single structure by means of a consistent kinematical synthesis. In recognition of smaller elastic motions, a perturbation approach is developed whereby the rigid-body maneuvering of the system defines the zero-order kinematical dynamics, while the elastic motions and perturbations from the rigid-body maneuvering define the first-order kinematical synthesis. As a numerical example, the Planar Articulating Controls Experimental (PACE) test article is maneuvered according to a bang-bang control law by means of torque applied to the shoulder and the elbow. The numerical simulation shows a close match with the detailed modal survey View full abstract»

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  • Theoretical analysis of the sequential lobing technique

    Page(s): 282 - 293
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    A theoretical analysis of the sequential lobing technique for target angle tracking is presented. The signal power received by each antenna beam is assumed to pass through a logarithmic amplifier. A rigorous statistical approach is adopted in the analysis for both non-fluctuating and fluctuating targets. Closed form expressions are derived for the normalized mean error and rms error of the angle estimate for Swerling 0, I, II, and III targets. Results are compared with those obtained using a simplified approach for the non-fluctuating target View full abstract»

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  • Two-dimensional adaptive array for spatially separating and tracking uncorrelated sources

    Page(s): 93 - 101
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    A new structure for the separation and tracking of uncorrelated sources through the use of a 2-dimensional adaptive array is proposed and investigated. The structure consists of a matrix preprocessing beamformer designed to result in outputs which are due to individual sources in the steady state. The preprocessing weights of the beamformer are calculated using the estimated locations of the sources and are updated periodically. Continuous estimation of the source locations is accomplished by using the beamformer outputs to adaptively eliminate correlated components in a reference element of the array while the structure proposed may have rather erratic initial convergence behavior, it has the advantages of being simple to be implemented, fast in tracking, and well suited for applications in mobile communication systems for increasing system capacity View full abstract»

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  • Block floating point for radar data

    Page(s): 308 - 318
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (916 KB)  

    Integer, floating point, and block floating point (BFP) data formats are analyzed and compared in order to establish the mathematical tools for selection of an optimal format which fulfils the demands of high resolution radar (SAR) data to large dynamic range and adequate S/N. The analysis takes quantization noise and saturation distortion into account and concludes that it is preferred to use small blocks and a (new) modified BFP format applying fractional exponents. Data from the EMISAR radar system are applied to illustrate the merits of the different schemes View full abstract»

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  • Design and analysis of a regulated peak-power tracking system

    Page(s): 84 - 92
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    A regulated peak-power tracking (RPPT) system for space power application is proposed. Large-signal stability analysis is provided to understand the main four different modes of operations of the system, as well as the mode transitions. A simple and effective control scheme for the system is also proposed. Small-signal analysis is performed thereafter to provide design optimization, and the predictions are verified by computer simulations View full abstract»

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  • Multiple-model estimation with variable structure. IV. Design and evaluation of model-group switching algorithm

    Page(s): 242 - 254
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1204 KB)  

    For pt. III see ibid., vol. 35, pp. 225-41 (1999). A variable-structure multiple-model (VSMM) estimator, called model-group switching (MGS) algorithm, has been presented in Part III, which is the first VSMM estimator that is generally applicable to a large class of problem with hybrid (continuous and discrete) uncertainties. In this algorithm, the model-set is made adaptive by switching among a number of predetermined groups of models. It has the potential to be substantially more cost-effective than fixed-structure MM (FSMM) estimators, including the Interacting Multiple-Model (IMM) estimator. A number of issues of major importance in the application of this algorithm are investigated here, including the model-group adaptation logic and model-group design. The results of this study are implemented via a detailed design for a problem of tracking a maneuvering target using a time-varying set of models, each characterized by a representative value of the expected acceleration of the target. Simulation results are given to demonstrate the performance (based on more reasonable and complete measures than commonly used rms errors alone) and computational complexity of the MGS algorithm, relative to the fixed-structure IMM (FSIMM) estimator using all models, under carefully designed and fair random and deterministic scenarios View full abstract»

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  • Doppler ambiguity resolution using optimal multiple pulse repetition frequencies

    Page(s): 371 - 379
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    Ferrari, Berenguer, and Alengrin (ibid., vol. 33, pp. 738-51, 1997) proposed an algorithm for velocity ambiguity resolution in coherent pulsed Doppler radar using multiple pulse repetition frequencies (PRFs). In this algorithm, two step estimations (folded frequency and ambiguity order) for the Doppler frequency is used by choosing particular PRF values. The folded frequency is the fractional part of the Doppler frequency and is estimated by averaging the folded frequency estimates for each PRF. The ambiguity order is the integer part of the Doppler frequency and is estimated by using the quasi-maximum-likelihood criterion. The PRF are grouped into pairs and each pair PRF values are symmetric about 1. The folded frequency estimate for each pair is the circular mean of the two folded frequency estimates of the pair due to the symmetry property. We propose a new algorithm based on the optimal choice of the PRF values, where the PRF values are also grouped into pairs. In each pair PRF values, one is given and the other is optimally chosen. The optimality is built upon the minimal sidelobes of the maximum likelihood criterion. Numerical simulations are presented to illustrate the improved performance View full abstract»

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  • Neural and fuzzy reconstructors for the virtual flight data recorder

    Page(s): 61 - 71
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    The results are presented of a comparative study evaluating the performance of neural network (NN) and fuzzy logic reconstructors (FLRs) for the development of a virtual flight data recorder (VFDK). Typical flight data recorders (FDRS) on commercial airliners do not record the aircraft control surface deflections. These dynamic parameters are critical in the investigation of an accident or an uncommanded maneuver. The results are shown relative to a VFDR based on a neural network simulator (NNS) along with a neural network reconstructor (NNR) or a FLR The NNS is trained off-line, using available flight data for the particular aircraft, for the purpose of simulating any desired dynamic output recorded in current FDRs. The NNS is then interfaced with the NNR or with the FLR. The output of the two reconstructors are the control surface deflections which minimize a performance index based on the differences between the available data from the FDR and the output from the NNS. The study tested with night data from a B737-300 shows that both schemes, the one with the NNR and the one with the FLR, provide accurate reconstructions of the control surface deflections time histories View full abstract»

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  • Design and comparison of mode-set adaptive IMM algorithms for maneuvering target tracking

    Page(s): 343 - 350
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    The variable-structure multiple model (MM) state estimation approach is utilized for maneuvering aircraft (MA) radar tracking. Two adaptive time-varying mode-set interacting multiple model (IMM) tracking filters are designed and investigated: switching grid (SG) IMM and adaptive grid (AG) IMM algorithms, By Monte Carlo simulations the performances of the algorithms and the respective fixed grid (FG) IMM filter are evaluated and compared over different flight scenarios. It is shown that for the considered specific maneuvering target tracking problem, the SGIMM and AGIMM tracking filters significantly outperform the corresponding fixed structure version (the FGIMM filter) with respect to performance-to-computational load ratio View full abstract»

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  • Phase quantized SAR signal processing: theory and experiments

    Page(s): 201 - 214
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    A complete theory of synthetic aperture radar (SAR) processing from phase-only data is presented, for both analogue and coded raw signals and reference functions. Appropriate processing architectures are presented as well as quality indexes to judge performance of the selected coding. The analysis encompasses both images and interferometric fringes for interferometry SAR (IFSAR) application. Theoretical results are validated by a large number of experiments, comparing the performance of the suggested coding levels, and their combinations between raw and reference functions. Experiments are extended until the comparison of final digital elevation models View full abstract»

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  • SAR imaging of moving targets

    Page(s): 188 - 200
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    A method of forming synthetic aperture radar (SAR) images of moving targets without using any specific knowledge of the target motion is presented. The new method uses a unique processing kernel that involves a one-dimensional interpolation of the deramped phase history which we call keystone formatting. This preprocessing simultaneously eliminates the effects of linear range migration for all moving targets regardless of their unknown velocity. Step two of the moving target imaging technique involves a two-dimensional focusing of the movers to remove residual quadratic range migration errors. The third and last step removes cubic and higher order defocusing terms. This imaging technique is demonstrated using SAR data collected as part of DARPA's Moving Target Exploitation (MTE) program View full abstract»

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  • Multiple-model estimation with variable structure. III. Model-group switching algorithm

    Page(s): 225 - 241
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1528 KB)  

    A general multiple-model (MM) estimator with a variable structure (VSMM), railed model-group switching (MGS) algorithm, is presented. It assumes that the total set of models can be covered by a number of model groups, each representing a cluster of closely related system behavior patterns or structures, and a particular group is running at any given time determined by a hard decision. This algorithm is the first VSMM estimator that is generally applicable to a large class of problems with hybrid (continuous and discrete) uncertainties. It is also easily implementable. It is illustrated, via a simple fault detection and identification example, that the MGS algorithm provides a substantial reduction in computation while having identical performance with the fixed-structure Interacting Multiple-Model (FSIMM) estimator View full abstract»

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  • Solution to a multisensor tracking problem with sensor registration errors

    Page(s): 354 - 363
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    An on-line solution to the aircraft tracking problem with a distributed network of 3D sensors that are imperfectly registered is presented. Errors in the relative positions and orientations of the sensors are modelled and estimated by an extended Kalman filter [EKF], along with the track variables. This optimal solution, tractable for a limited number of targets, is compared through Monte-Carlo simulation with a suboptimal filter that neglects the sensor systematic errors. The registration errors substantially degrade the accuracy of the aircraft position estimates. The performance of the optimal filter depends on whether the registration errors are to be determined in an absolute or relative setting. When the sensor systematic errors are estimated relative to one of the sensors, the optimal filter performance is excellent. The simulation results are confirmed by a covariance analysis of the optimal filters View full abstract»

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  • Kalman filtering approach to multispectral/hyperspectral image classification

    Page(s): 319 - 330
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    Linear unmixing is a widely used remote sensing image processing technique for subpixel classification and detection where a scene pixel is generally modeled by a linear mixture of spectral signatures of materials present within the pixel. An approach, called linear unmixing Kalman filtering (LUKF), is presented, which incorporates the concept of linear unmixing into Kalman filtering so as to achieve signature abundance estimation, subpixel detection and classification for remotely sensed images. In this case, the linear mixture model used in linear unmixing is implemented as the measurement equation in Kalman filtering. The state equation which is required for Kalman filtering but absent in linear unmixing is then used to model the signature abundance. By utilizing these two equations the proposed LUKF not only can detect abrupt changes in various signature abundances within pixels, but also can detect and classify desired target signatures. The performance of effectiveness and robustness of the LUKF is demonstrated through simulated data and real scene images, Satellite Pour I'Observation de la Terra (SPOT) and Hyperspectral Digital Imagery Collection (HYDICE) data View full abstract»

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  • Radar synthetic vision system for adverse weather aircraft landing

    Page(s): 2 - 14
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2500 KB)  

    A synthetic vision system (SVS) is described for aid in landing aircraft in poor weather conditions. The system consists of a scanning millimeter wave radar, heads-up display and real-time signal processing hardware. A suite of fast image processing algorithms are used for enhancing and displaying of the imagery. The system has been tested in number of tower and flight demonstration during actual adverse weather conditions. The significance of the work is in both system demonstration of the overall concept and the novelty of its signal processing algorithms View full abstract»

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  • High resolution radar clutter statistics

    Page(s): 43 - 60
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    The generalized compound probability density function (GC-pdf) is presented for modeling high resolution radar clutter. In particular, the model is used to describe deviation of the speckle component from the Rayleigh to Weibull or other pdfs with longer tails. The GC-pdf is formed using the generalized gamma (GΓ) pdf to describe both the speckle and the modulation component of the radar clutter. The proposed model is analyzed and thermal noise is incorporated into it. The validation of the GC-pdf with real data is carried out employing the statistical moments as well as goodness-of-fit tests. A large variety of experimental data is used for this purpose. The GC-pdf outperforms the K-pdf in modeling high resolution radar clutter and reveals its structural characteristics 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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Editor-in-Chief
Lance Kaplan
Army Research Laboratory