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Aerospace and Electronic Systems, IEEE Transactions on

Issue 3 • Date May 1985

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Displaying Results 1 - 25 of 30
  • Table of contents

    Page(s): c1
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  • IEEE Aerospace and Electronic Systems Society

    Page(s): c2
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  • From the Editors

    Page(s): 273
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  • On the Orbit Determination Problem

    Page(s): 274 - 291
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    Various important aspects of the satellite orbit determination problem are critically discussed with a view to emphasizing the importance of a wise choice of suitable system models, coordinates sets, and estimators. We describe several aspects of the orbit determination process and also review much of the available literature on the application of Kalman-filter type algorithms to the problem of near-Earth, geosynchronous, and deep-space mission type orbit determination. Some features of on-board orbit determination are also addressed. It is believed that this review with a touch of tutorial will enable engineers and scientists to arrive at an orbit determination methodology (ODM) that will have attributes of good numerical stability, efficiency, and precision in orbit estimation. View full abstract»

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  • MMAE-Based Control with Space-Time Point Process Observations

    Page(s): 292 - 300
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    A multiple model adaptive estimator (MMAE) has been formulated to estimate the state of a dynamic system modeled by a linear stochastic differential equation, from which measurements, described as a noise-corrupted space-time point process functionally related to that state, are extracted. Assumed certainty equivalence is used to combine such an estimator with the LQ full-state feedback controller to synthesize a practical, implementable controller. Performance of the estimator and resultant controller characteristics are investigated via simulation as a function of approximation method used to limit the full-scale estimator to finite dimensionality and also as a function of important parameters defining the dynamics and observation processes. View full abstract»

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  • Small-Signal Model for the Series Resonant Converter

    Page(s): 301 - 319
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    The results of a previous discrete-time model of the series resonant dc-dc converter are reviewed and from these a small signal dynamic model is derived. This model is valid for low frequencies and is based on the modulation of the diode conduction angle for control. The basic converter is modeled separately from its output filter to facilitate the use of these results for design purposes. Experimental results are presented. View full abstract»

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  • Radiation-Supported Space Mirror: Overview of Concept

    Page(s): 320 - 330
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    A high-altitude communications reflector can be supported by radiation pressure beamed at it from below. Potential applications of such a communications device are reviewed. The supporting radiation can balance the weight of the mirror as well as inertial effects, including mirror drift toward the equator. Approximately polarized supporting radiation can rotate the mirror. The reflected signal may serve to monitor mirror orientation. Questions of stability are investigated when the mirror is made of fibers that can support only tension (not compression, shear, or bending.) If the supporting radiation beam is appropriately configured, the mirror can be stabilized with respect to vertical and horizontal displacements, libration, and distortion. View full abstract»

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  • Ground Radiation Pattern Generated by High-Altitude Reflectors

    Page(s): 331 - 337
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    A method is given to calculate the shape a high-altitude reflector must have to produce any intensity distribution inside the illuminated ground area. The method consists of setting up and solving a differential equation appropriate to the required ground intensity distribution. Cylindrical and spherical mirrors are discussed in detail, and mirror shapes for producing a particular type of uniform ground illumination are derived. These shapes approach paraboloids in the limit when the mirror altitude is much greater than the diameter of the illuminated area. View full abstract»

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  • Extensions to the Step Transform SAR Processing Technique

    Page(s): 338 - 344
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    In previous descriptions of the step transform SAR azimuth compression algorithm, it has been assumed that the azimuth signal is linear FM and is strictly confined within a single range cell. These conditions do not always hold. Under stringent imaging conditions range curvature occurs, i.e., a nonlinear range migration of the energy associated with a point target takes place. If the system must also operate at a high squint angle, the azimuth signal becomes nonlinear FM. This paper describes extensions to the basic step transform algorithm that allow these imaging situations to be accommodated. View full abstract»

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  • Automatic Solution of Nthorder Optimal Control Problems

    Page(s): 345 - 350
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    An automatic method for obtaining the numerical solution of a certain class of nth-order nonlinear optimal control problems is described. The derivatives required for the solution of the two-point boundary value problem are computed automatically. The user of the program need only input the Hamiltonian function by calling the appropriate Fortran subroutines. This paper extends the methods described by the authors in previous papers in that it increases the order of the system that can be handled by the program from second order to the general nth order. View full abstract»

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  • Algorithms for Improved, Heading Assisted, Maneuver Tracking

    Page(s): 351 - 359
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    The evolution of the SSR mode S system makes it possible to receive airborne measurements at the ground station. The possibility of using data-linked heading measurements to assist present trackers to track maneuvering aircraft is investigated. The quality to be expected from heading measurements is investigated from available on-board recordings. Maneuver detection and false measurement rejection schemes are developed, and finally suitable maneuver tracking filters are constructed and evaluated. View full abstract»

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  • The Performance of an LMS Adaptive Array with Frequency Hopped Signals

    Page(s): 360 - 371
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    The performance of an LMS adaptive array with a frequency hopped, spread spectrum desired signal and a CW interference signal is examined. It is shown that frequency hopping has several effects on an adaptive array. It causes the array to modulate both the amplitude and the phase of the received signal. Also, it causes the array output SINR (signal-to-interference-plus-noise ratio) to vary with time and thus increases the bit error probability for the received signal. Typical curves of the desired signal modulation and the time-varying SINR at the array output are presented. It is shown how the array performance depends on hopping frequency, frequency jump size, interference frequency, signal arrival angles, and signal powers. View full abstract»

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  • Spectral Analysis of Optimal and Suboptimal Gyro Monitoring Filters

    Page(s): 372 - 378
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    Gyro monitoring filters are used to estimate and correct gyro drift rates of local-level inertial navigation systems. Conventional gyro monitoring filters are usually designed based on a simplified model of gyro drift rate. Furthermore, the effectiveness of these filters-and of many filters of the "Kalman" type-is often measured in terms of the root mean square (rms) criterion in contrast to the spectral content criterion typical of classical Wiener filtering theory. This paper has two objectives: to propose a gyro monitoring filter which is based on a more detailed model of gyro drift rate; and to propose a method of filter performance evaluation which uses as criterion a measure of the spectral content of the error process. The proposed gyro monitoring filter is shown to have improved spectral contents resulting in superior navigation performance for the gyro error models used in the calculations (comparable to commercial-grade aircraft gyros). View full abstract»

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  • New Data Bus Interface Technique

    Page(s): 379 - 384
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    Data bus systems as defined in MIL-STD-1553B are widely used in aerospace instrumentation systems for digital data transmissions between units on the bus. Although the bus is protected against a short circuit which may occur in the remote unit electronics or transformer, it has no protection against a cable termination failure. Open or short failure along main bus cable results in failure of the entire bus system. A new data bus interface technique is described which is insensitive to cable termination failure. The central feature of this new interface circuit is that communication between main unit and remote units is not affected by the cable termination failure. In applications such as multistage missiles, no provisions need be made for retermination in the cable characteristic impedance after stage separation. The key to this new technique is a directional coupling transformer which is only slightly more complicated than standard interface transformers. Design equations for directional coupling transformer and experimental results of new data bus systems are presented. View full abstract»

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  • On Optimal Minimax Jamming and Detection of Radar Signals

    Page(s): 385 - 393
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    A game between an intelligent jammer J and decision maker DM is considered. DM seeks to detect a coherent slowly fading narrowband signal under a Neyman-Pearson criterion. His observations are corrupted with additive narrowband noise, the source of which is J's jamming with a power constraint, but otherwise almost arbitrary statistics. DM knows J's action but the converse is not true. When the number of samples increases asymptotically, a minimax solution for the game exists where the jamming is Gaussian, independent of the desired signal amplitude level and probability distribution. The same result also holds for detection of a nonrandom baseband signal. View full abstract»

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  • Adaptive Optical Target Detection Using Correlated Images

    Page(s): 394 - 405
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    A method for target detection that achieves clutter rejection by the use of multiple observations of the same target scene is developed. Multiple scene observations can be obtained by processing separate frequency bands of the same target scene or by recursively processing sequential observations in time. Optimal detection algorithms are developed, based on the assumption that the image intensity can be modeled as a variable mean spatial Gaussian process. Several fast detection algorithms are derived which make use of the fact that the covariance matrices of many optical and infrared (IR) images can be accurately approximated by diagonal matrices. These algorithms provide efficient solutions to the problem of processing multiple correlated scenes or multiple sequential imaging. Computer simulations based on actual optical and IR image data were used for checking the theoretical results. The new detection algorithms achieved performance improvement in detection signal-to-noise ratio of up to 10 dB over conventional target correlation methods. View full abstract»

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  • Information for authors

    Page(s): 406
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  • Particle Velocity Estimation Using Kalman Filtering

    Page(s): 407 - 419
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    The velocity of a moving particle can be estimated by using the least squares method (LSM), but the estimation accuracy is not high. Here, a Kalman filtering method (KFM) is applied to estimate this velocity. A Kalman filtering formulation of the moving particle velocity is described and has been realized on a digital computer. According to a vast number of printouts, the advantages of KFM over LSM are a short filtering stability time and a high filtering accuracy. View full abstract»

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  • Leasecraft Power System Leasecraft Power System

    Page(s): 420 - 426
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    Various building blocks of the Fairchild Leasecraft Power System are described in detail after a brief description of the evolution of the Leasecraft spacecraft. The principle of maximum power transfer from a solar cell array has been employed in the power system advantageously. Results of detailed tradeoff studies are presented which led to the selection of the decentralized regulation concept utilizing a nondissipative unregulated main (power) bus approach. Finally the main features of the Leasecraft Power System, i.e., flexibility, reliability, input and output electrical characteristics, etc. are presented. View full abstract»

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  • Tests of Direct-Sampling Coherent Detection with a Laboratory Analog-to-Digital Converter

    Page(s): 430 - 432
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    Phase accuracy and simplicity advantages of a direct-sampling coherent detection (DCD) system were demonstrated by computer simulation in earlier correspondence. This correspondence reviews the DCD approach and reports the results of experiments involving digitized samples of analog signals taken by a high-quality, off-the-shelf A/Dconverter. IF signals near 10, 20, and 30 MHz were sampled at 5 MHzresulting in rms DCD phase errors generally below 0.50 compared witherrors less than 0.20 computed in the earlier simulations. View full abstract»

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  • On the Ambiguity Function of Random Binary-Phase-Coded Waveforms

    Page(s): 432 - 436
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    The ambiguity function of truly random binary-phase-coded waveforms, as an approximation to those waveforms commonly employed in binary-modulated pseudonoise systems/encoded radar systems, is investigated. In a statistical sense, the ambiguity function is analytically derived in which the normally used deterministic cross-correlation process is replaced by its ensemble average. Various Doppler filter responses are presented and discussed. The results are compared with those obtained by transmitting an aperiodic maximum length pseudorandom sequence. It is shown that the ambiguity function of the latter case is closely represented by the ensemble-average response of the truly random binary signal. View full abstract»

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  • 1985 Pioneer Award

    Page(s): 437 - 439
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  • Synthetic Aperture Radars

    Page(s): 440 - 443
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    This is the 1984 Pioneer Award story-told in the author's own words. View full abstract»

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  • Call for Pioneer Award Nominations

    Page(s): 444
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Aims & Scope

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

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Lance Kaplan
Army Research Laboratory