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Aerospace and Electronic Systems, IEEE Transactions on

Issue 2 • Date March 1985

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Displaying Results 1 - 18 of 18
  • Table of contents

    Publication Year: 1985 , Page(s): c1
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  • IEEE Aerospace and Electronic Systems Society

    Publication Year: 1985 , Page(s): c2
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  • From the Editors

    Publication Year: 1985 , Page(s): 169
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  • Sets of One and Higher Dimensional Welti Codes and Complementary Codes

    Publication Year: 1985 , Page(s): 170 - 179
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1680 KB)  

    A Welti code is a binary sequence with an impulse-like autocorrelation function. A set of such codes may possess vanishing cross-correlation functions. The elements of Welti codes must be members of a set of at least two orthogonal vectors or subcodes. First, methods for synthesizing sets of one-dimensional Welti codes with vanishing cross-correlation functions, and conditions upon their existence are discussed. Then, construction methods of sets of two and higher dimensional Welti codes are presented. Based on these constructions, further sets of mutually orthogonal complementary codes in one or more dimensions can be derived. The use of such signals relates to various topics such as communication, radar and navigation systems, measuring and identification in one or higher dimensional systems, synchronization and spatial alignment, or coded aperture imaging. View full abstract»

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  • Adaptive Interpolated Time-Delay Estimation

    Publication Year: 1985 , Page(s): 180 - 199
    Cited by:  Papers (19)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3427 KB)  

    An adaptive delay-estimation (ADE) algorithm is proposed for the continuous tracking of time-delay. The method uses an adaptive delay line which is interpolated by a first-order filter. Two delay-line interpolating filters are considered, each having a single coefficient which is estimated in real time. The first implements linear interpolation, and the second interpolates using a first-order allpass filter. Since the ADE algorithm is derived from recursive Gauss-Newton optimization, it can be viewed as a recursive maximum likelihood (RML) algorithm for time-delay estimation. View full abstract»

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  • Observability Requirements for Three-Dimensional Tracking via Angle Measurements

    Publication Year: 1985 , Page(s): 200 - 207
    Cited by:  Papers (52)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1635 KB)  

    Observability requirements previously established for bearings-only tracking in two dimensions are extended to a class of three-dimensional estimation algorithms capable of processing any pairwise combination of azimuth bearing, conical bearing, and depth/elevation angle measurements. Although these algorithms are intrinsically nonlinear, it is shown that they can be analyzed in a linear framework without sacrificing mathematical rigor. A simplified observability criterion, applicable to both autonomous and nonautonomous linear systems, is presented and utilized to specify conditions on own-ship motion which are both necessary and sufficient for a unique tracking solution. Further analysis reveals that observability dependence on own-ship maneuvers for the three-dimensional algorithms considered here parallels the concomitant two-dimensional requirements. An interesting difference, however, is that under certain conditions, a unique tracking solution can be obtained in three dimensions for unaccelerated own-ship motion. View full abstract»

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  • The Shape of Doppler Spectra from Precipitation

    Publication Year: 1985 , Page(s): 208 - 219
    Cited by:  Papers (13)
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    From October 1982 through May 1983 an extensive weather clutter registration program was executed near the Dutch coast. Coherent echo series of 2 s were obtained from a cluster of adjacent antenna pencil beams every 10 or 15 min., mainly between 16:00 and 08:30 h and on the weekends. The beam cluster was pointed toward the intensity maximum of the clutter volume. The radar operated at 5650 MHz. Spectra with 10 Hz Doppler resolution have been computed by averaging over 19 discrete Fourier transforms of overlapping and tapered subseries of 200 echo vectors. To quantify the deviation from a Gaussian shape a spectral variability is defined which is computed for every estimated spectrum. It is found that the deviation from Gaussian is considerable in about one-fourth of the spectra. A selection of "typical worst case" spectra is presented. View full abstract»

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  • Fault Tolerant Computer System for the A129 Helicopter

    Publication Year: 1985 , Page(s): 220 - 229
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3007 KB)  

    The A129 integrated multiplex system (IMS) is a highly reliable computer system designed to implement automatic flight control, navigation, system monitoring, and other flight-critical and mission related tasks. The reliability of the IMS has been achieved through the development of hardware-implemented and software implemented fault-tolerance techniques which exploit several unique architectural and hardware characteristics. This paper describes the fault-tolerance design philosophy, the IMS architecture, the fault detection and fault recovery techniques, and the hardware and software structures. Also presented is a Markov reliability analysis which was used to quantify the reliability of the system. View full abstract»

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  • Optimum Magnetic Circuit Configurations for Permanent Magnet Aerospace Generators

    Publication Year: 1985 , Page(s): 230 - 255
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5140 KB)  

    In the design of high-speed low-power electrical generators for unmanned aircraft and spacecraft, maximization of specific output (power/weight) is of prime importance. Several magnetic circuit configurations (radial-field, axial-field, flux-squeezing, homopolar) have been proposed, and in this paper the relative merits of these configurations are subjected to a quantitative investigation over the speed range 10 000-100 000 rev/min and power range 250 W-10 kW. The advantages of incorporating new high energy-density magnetic materials are described. Part 1 deals with establishing an equivalent circuit for permanent-magnet generators. For each configuration the equivalent circuit parameters are related to the physical dimensions of the generator components and an optimization procedure produces a minimum volume design at discrete output powers and operating speeds. The technique is illustrated by a quantitative comparison of the specific outputs of conventional radial-field generators with samarium cobalt and alnico magnets. In Part II the specific outputs of conventional, flux-squeezing, and claw-rotor magnetic circuit configurations are compared. The flux-squeezing configuration is shown to produce the highest specifilc output for small sizes whereas the conventional configuration is best at large sizes. For all sizes the claw-rotor configuration is significantly inferior. In Part I1l the power densities available from axial-field and flux-switching magnetic circuit configurations are maximized, over the power range 0.25-10 kW and speed range 10 000-100 000 rpm, and compared to the results of Parts I & II. For the axial-field configuration the power density is always less than that of the conventional and flux-squeezing radial-field configurations. View full abstract»

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  • Call for Pioneer Award Nominations

    Publication Year: 1985 , Page(s): 256
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  • Automated VOR Ground Check Techniques

    Publication Year: 1985 , Page(s): 257 - 261
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (796 KB)  

    Field conversions of many conventional VOR and VORTAC facilities to remote maintenance monitoring, which includes provisions for automated VOR ground check procedures, has been under way in the United States since 1982. A question that has arisen as a result of this effort concerns the minimum number of ground-check points that must be used in order that the bearing-error function can be resolved into its octantal as well as its quadrantal and "duantal" components. Some fundamental considerations relating to that question are examined here. View full abstract»

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  • Closed-Form Solution of a Recursive Tracking Filter with a Priori Velocity Initialization

    Publication Year: 1985 , Page(s): 262 - 264
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (413 KB)  

    A closed-form solution is presented for the transient gains and covariances of a two-state tracking filter which is initialized with a finite a priori velocity error variance. The formulas are applied to long-range tracking and fire control problems, and are shown to agree (in the limit) with classical formulas for a least-squares line estimator and a bias-in-noise estimator. View full abstract»

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  • Comment on "Performance Analysis of Monopulse Receivers for Secondary Surveillance Radar"

    Publication Year: 1985 , Page(s): 264 - 266
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    The increase in estimation error near boresight with a sum and difference amplitude comparison monopulse receiver can be prevented by using an adequate maximum likelihood estimator. View full abstract»

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  • Evaluation of Collapsing Losses in Digital Radar Detection

    Publication Year: 1985 , Page(s): 266 - 271
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    The collapsing losses, due to multiple channel combinations, are evaluated for some digital radar detection schemes including the moving window detector. View full abstract»

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  • Author's Corrections to: "Attitude Determination from Vector Observations: Quaternion Estimation"

    Publication Year: 1985 , Page(s): 271
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  • Emendations to "Simple Eigenvalue-Equalizing Preprocessor for Broadband Power Inversion Array"

    Publication Year: 1985 , Page(s): 272
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    First Page of the Article
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  • IEEE Aerospace and Electronic Systems Society Organization

    Publication Year: 1985 , Page(s): 272-a
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  • IEEE Aerospace and Electronic Systems Society

    Publication Year: 1985 , Page(s): 272-b
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    Freely Available from IEEE

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