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Aerospace and Electronic Systems, IEEE Transactions on

Issue 4 • Date July 1982

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  • Table of contents

    Publication Year: 1982 , Page(s): c1
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  • IEEE Aerospace and electronic Systems Society

    Publication Year: 1982 , Page(s): c2 - 518-a
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  • From the Editors

    Publication Year: 1982 , Page(s): 351
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  • Low-Error Bearing Estimation in Shallow Water

    Publication Year: 1982 , Page(s): 352 - 357
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1759 KB)  

    The multipath effect due to sound propagation in shallow water causes bearing errors in horizontal line arrays for all angles different from broadside when conventional resolution methods like beamformer or maximum entropy method are used. Error-free bearing estimates can be achieved only by means of generalized power estimators which use a priori knowledge about the spatial channel statistics. This a priori knowledge is usually unknown. The method described makes use of a pilot source which transmits training signals in order to achieve an estimate for a suboptimum spatial signal covariance matrix which is used for field matching. View full abstract»

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  • A Microcomputer-Controlled Laser Beam Analyzer

    Publication Year: 1982 , Page(s): 358 - 368
    Cited by:  Papers (1)
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    A microcomputer-controlled laser beam analyzer is described. It uses five INTEL 8080 microcomputers to calculate the beam's peak intensity, peak intensity coordinates, centroid coordinates, beam energy, and beam quality in real time. Its application to the U.S. Army's gas-dynamic laser is illustrated. View full abstract»

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  • Radar/Sonar Signal Design for Bounded Doppler Shifts

    Publication Year: 1982 , Page(s): 369 - 380
    Cited by:  Papers (3)
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    In many detection and estimation problems, Doppler frequency shifts are bounded. For clutter or multipath that is uniformly distributed in range and symmetrically distributed in Doppler shift relative to the signal, detectability of a point target or a communication signal is improved by minimizing the weighted volume of the magnitude-squared autoambiguity function. When clutter Doppler shifts are bounded, this volume is in a strip containing the range axis on the range-Doppler plane. For scattering function estimation, e.g., for weather radar, Doppler flow meters, and distributed target classifiers, it is again relevant to minimize ambiguity volume in a strip. Strip volume is minimized by using a pulse train, but such a signal has unacceptably large range sidelobes for most applications. Other waveforms that have relatively small sidelobe level within a strip on the range-Doppler plane, as well as small ambiguity volume in the strip, are obtained. The waveforms are composed of pulse pairs that are phase modulated with Golay complementary codes. View full abstract»

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  • Generalized Feedback Decoding of Convolutional Codes

    Publication Year: 1982 , Page(s): 381 - 391
    Cited by:  Papers (1)
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    The use of convolutional codes with feedback decoding is a common error-correction technique in simple communication systems. A drawback of conventional feedback decoding is the limitation to a class of self-orthogonal codes which, in general, are nonoptimum. Based on distance properties of the utilized code and test-error pattern analysis, we propose generalized feedback decoding which does not have the abovementioned limitation. This is minimum distance decoding and can be applied to any convolutional code while still maintaining its simplicity. Therefore, it has the advantage of being easily adopted in existing systems. We can use the relatively complicated Viterbi or sequential decoders in larger terminals and, with the same code, use the proposed decoders in smaller terminals; otherwise, both large and small terminals must utilize the same type of decoder. The proposed decoding scheme could also be used to simplify and speed up sequential decoding. In addition, comparisons of the proposed decoder with other feedback decoders are presented. View full abstract»

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  • The Effect of Random Steering Vector Errors in the Applebaum Adaptive Array

    Publication Year: 1982 , Page(s): 392 - 400
    Cited by:  Papers (43)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1759 KB)  

    The effect of random errors in the steering vector of an Applebaum adaptive array is examined. Each component of the steering vector is assumed to have a random error component uncorrelated between elements. The array output signal-to-interferenceplus-noise ratio (SINR) is computed as a function of the error variance. It is shown that the array output SINR becomes more sensitive to steering vector errors as more elements are added to the array and as the received desired signal power becomes larger. The variance of the steering vector error that may be tolerated depends on the required desired signal dynamic range. The larger the dynamic range that must be accommodated, the smaller the error variance must be. View full abstract»

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  • Calculating Detection Probabilities for Systems Employing Noncoherent Integration

    Publication Year: 1982 , Page(s): 401 - 409
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1713 KB)  

    Cumulative probability distributions that occur in radar and sonar detection problems are calculated directly from the characteristic function by using a Fourier series. The error in the result is controlled by two parameters which can be adjusted to suit the application. The technique is applied to the problem of determining the detection performance of consecutive discrete Fourier transforms (DFTs) for a narrowband Gaussian signal with a rectangular spectrum. Since the characteristic function is used directly in its product form this technique does not suffer from the numerical problems associated with the partial fraction approach. The technique can handle many different problems in a single computational structure making it a valuable tool in system performance studies. View full abstract»

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  • Bistatic Interference between Neighboring Radars

    Publication Year: 1982 , Page(s): 410 - 415
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    Radar transmitters characteristically generate broadband noise sidebands [1] over the entire tunable frequency band of the system for the duration of the transmitted pulse. The noise will be backscattered over a substantial range interval. In certain circumstaces, this bistatic reflection of ground clutter emerges as the predominant mode of interference between adjacent radars operating in common bands. Closed form mathematical expressions are derived which relate this mutual interference to the system noise temperature. These results in turn are applied to a typical S-band radar. View full abstract»

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  • Angular Accuracy of the Binary Moving Window Radar Detector

    Publication Year: 1982 , Page(s): 416 - 422
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1693 KB)  

    The angular accuracy of a search radar depends on the extraction technique. For the case of a binary moving window extractor, the accuracy is evaluated in different operational conditions including target scintillation. A beam-splitting technique that was devised to improve the accuracy is also evaluated and compared with the binary moving window. View full abstract»

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  • Bistatic Synthetic-Aperture Radar Imaging of Rotating Objects

    Publication Year: 1982 , Page(s): 423 - 431
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1860 KB)  

    The imaging properties of a focused radar aperture synthesized by object rotation are considered. The ring-shaped aperture synthesized by the object rotation can provide high-resolution two-dimensional imaging using only monochromatic irradiation. The case of monochromatic irradiation is extended to the polychromatic case and to equivalent bistatic geometries. These techniques offer practical methods for radar imaging of rotating objects with scattering centers visible over large angular extents. View full abstract»

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  • Biased Estimation Properties of the Pseudolinear Tracking Filter

    Publication Year: 1982 , Page(s): 432 - 441
    Cited by:  Papers (49)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1746 KB)  

    Estimation bias in the pseudolinear filter applied to bearings-only target tracking is discussed. Approximate expressions for the pertinent error terms are developed and subsequently used to predict tracking performance under realistic operating conditions. It is shown that once own-ship executes a maneuver, only the estimated range vector remains biased; the corresponding velocity vector becomes asymptotically unbiased. Further investigation reveals that this range bias is highly dependent upon geometry and can be altered by additional own-ship maneuvers. Experimental data are presented to support these findings. View full abstract»

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  • Estimating Noise Variances by Using Multiple Observers

    Publication Year: 1982 , Page(s): 442 - 448
    Cited by:  Papers (9)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1254 KB)  

    Unknown variances of the noises that excite a time-invariant, linear dynamic system and/or in the observation of its output can be estimated by use of multiple observers. One observer is needed, in general, for each unknown variance. Each observer is time invariant and has different gains from the others. It is shown that each unknown variance is a linear combination of the variances of the residuals of the observers. The required estimates of the noise variances are obtained by using the measured variances of the residuals. The method presented in this paper is illustrated by an application to determining noise parameters in a ring laser gyro. View full abstract»

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  • Modeling the Full-Bridge Series-Resonant Power Converter

    Publication Year: 1982 , Page(s): 449 - 459
    Cited by:  Papers (33)
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    A steady state model is derived for the full-bridge series-resonant power converter. Normalized parametric curves for various currents and voltages are then plotted versus the triggering angle of the switching devices. The calculations are compared with experimental measurements made on a 50 kHz converter and a discussion of certain operating problems is presented. View full abstract»

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  • Constant Voltage Digital Control of an AC Motor Positioning Servo

    Publication Year: 1982 , Page(s): 460 - 468
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1743 KB)  

    A theoretical approach is presented to digitally manipulating the drive frequency of an ac induction motor so as to allow the motor to be used in a closed loop positioning servo. Additionally, the basic power source can be a simple dc power supply such as a battery pack. A hardware demonstration of the loop is discussed which has achieved a convergence accuracy of a 0.3 mrad to a step input. View full abstract»

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  • Altitude Estimation Using Asynchronous α -β Tracking Filters

    Publication Year: 1982 , Page(s): 469 - 477
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1904 KB)  

    In the analysis of the ¿-ß tracking filter it is usually assumed that the tracking filter and data source operate in synchronism at a constant data rate. However, in a multisensor environment in which the tracking algorithm operates at fixed intervals, the tracking filter cannot be synchronized with the sensors. An analytical solution is obtained for the case in which the tracking filter and data source operate asynchronously with a ¿time-correction¿ process used to approximate the synchronous operation of the tracking filter. An example is given in which the effects of data quantization on the performance of an altitude tracking filter for air traffic control are examined. It is shown that the asynchronous operation of the tracking filter in the example without the time-correction process will result in significant errors in the predicted altitude. View full abstract»

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  • Analysis and Design of a Standardized Control Module for Switching Regulators

    Publication Year: 1982 , Page(s): 478 - 496
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3092 KB)  

    Three basic switching regulators: buck, boost, and buck/boost, employing a multiloop standardized control module (SCM) were characterized by a common small signal block diagram. Employing the unified model, regulator performances such as stability, audiosusceptibility, output impedance, and step load transient are analyzed and key performance indexes are expressed in simple analytical forms. More importantly, the performance characteristics of all three regulators are shown to enjoy common properties due to the unique SCM control scheme which nullifies the positive zero and provides adaptive compensation to the moving poles of the boost and buck/boost converters. This allows a simple unified design procedure to be devised for selecting the key SCM control parameters for an arbitrarily given power stage configuration and parameter values, such that all regulator performance specifications can be met and optimized concurrently in a single design attempt. View full abstract»

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  • Design Optimization for a Half-Bridge DC-DC Converter

    Publication Year: 1982 , Page(s): 497 - 508
    Cited by:  Papers (15)
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    A nonlinear programming technique using the penalty function method is employed for the minimum weight design of a halfbridge dc-dc buck power converter. The cost-effective computeraided approach provides a minimum weight design down to the details of the component level which concurrently meets all power circuit performance requirements. Important design insights and guidelines are obtained to readily assess 1) the tradeoffs between weight and loss as the switching frequency is increased, 2) the optimum operating frequency range over which the total weight/loss is minimized, 3) the impact of device characteristics on the total weight and loss profile. View full abstract»

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  • Comment on "Retention Probability in a Track-While-Scan Radar"

    Publication Year: 1982 , Page(s): 509 - 510
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    First Page of the Article
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  • Simple Expressions for Determining Radar Detection Thresholds

    Publication Year: 1982 , Page(s): 510 - 512
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    The threshold value required to obtain a specified false-alarm probability, when postdetection integration follows a square-law or an envelope detector, is frequently needed in theoretical and practical studies of radar signal processor performance. The determination of such threshold values requires a substantial numerical computational effort. In this correspondence, simple expressions are presented with which these thresholds can be determined with excellent accuracy using only a scientific calculator. View full abstract»

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  • 1982 Pioneer Award

    Publication Year: 1982 , Page(s): 513
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  • 1982 Pioneer Award

    Publication Year: 1982 , Page(s): 514 - 518
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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