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Aerospace and Electronic Systems, IEEE Transactions on

Issue 4 • Date July 1980

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Displaying Results 1 - 25 of 28
  • Table of contents

    Publication Year: 1980 , Page(s): c1
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  • IEEE Aerospace and Electronic Systems Society

    Publication Year: 1980 , Page(s): c2 - 543-a
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  • From the Editors

    Publication Year: 1980 , Page(s): 417
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  • Computational Precision Requirements for Optimal Weights in Adaptive Processing

    Publication Year: 1980 , Page(s): 418 - 425
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1453 KB)  

    The required accuracy for computing the estimated optimum weights of an adaptive processor has been analyzed by investigating the effects of errors in computing the inverse matrix. It is shown that the required precision depends upon the matrix. An equation for the general case is derived. Several special cases are considered in detail. It is shown that the case of a single interference source requires the highest precision. The least stressing case is identifi'ed and compared to the worst case. The requirements for a "typical" case are also considered. A comparison of the requirements for the covariance matrix estimation technique and for adaptive weight implementation using gradient descent techniques is given. It is shown that there is a dichotomy in that cases that do not stress one technique tend to stress the other. View full abstract»

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  • Crosstalk Resistant Receiver for M-ary Multiplexed Communications

    Publication Year: 1980 , Page(s): 426 - 433
    Cited by:  Papers (4)
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    Attention is directed to the problem of M-ary signal transmission from a multiplicity of synchronized information sources. A receiver processor is derived which suppresses the effect of crosstalk between nonorthogonal signals. The processor is valid for a general zero mean, noise environment. A probability of error bound is derived for the processor. Several examples illustrate the processor. View full abstract»

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  • A Quantitative Study of Pitfalls in the FFT

    Publication Year: 1980 , Page(s): 434 - 439
    Cited by:  Papers (100)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1385 KB)  

    The effects of aliasing (including pseudoaliasing), picket-fence effect, and leakage in the fast Fourier transform (FFT) are presented. A computer program was written to perform the FFT analysis of known inputs. The program has the capability of detecting aliasing by calculating an "aliasing coefficient" (Q), and will increase the sampling frequency and the number of points in the input sequence if aliasing occurs. The term "pseudoaliasing" is a phenomenon which is similar to aliasing (or fold-over) but related to the effects of picket fence and leakage. The "leakage coefficient" (ri) is a quantitative measure of the deviation from the fundamental frequency component with respect to the sampling frequency, when the input sequence has only one frequency component. View full abstract»

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  • Spread-Spectrum Signaling for Distributed Fiber Optic Systems

    Publication Year: 1980 , Page(s): 440 - 445
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1294 KB)  

    One of the stringent requirements on the receivers of distributed industrial fiber optic systems is fast and accurate adaptive thresholding and a wide dynamic range. This is due to the existence of variable link lengths and geometry, especially in multipleaccess situations, coupled with unipolar optical signaling. This paper analyzes the application of a simple spread-spectrum system in such fiber-optic data links. It proposes a detector model that yields a tractable expression for the probability of error. The optimum threshold and the probability of error are then related to the received optical power, bit rate, and spectrum-spreading factor. A procedure is indicated by which, based on the minimum expected received power, a spreading facor and a threshold are chosen to insure a given maximum error rate at all the receivers. View full abstract»

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  • Sample Size Considerations for Adaptive Arrays

    Publication Year: 1980 , Page(s): 446 - 451
    Cited by:  Papers (49)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1001 KB)  

    Digital control of adaptive arrays has been shown to be a feasible alternative to analog feedback-loop control. As the eigenvalue spread of the correlation matrix no longer controls the speed of adaption, one merely has to ensure that enough samples have been taken so that the matrix estimate is close to the true matrix. While previous studies have assumed ideal conditions, it is shown here that if the true signal direction is not known exactly or if the data containing the interference are corrupted by a desired signal, then more samples are required to ensure that the estimated weighting vector gives a near optimal performance. View full abstract»

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  • An Adaptive Antenna for Rejection of Wideband Interference

    Publication Year: 1980 , Page(s): 452 - 459
    Cited by:  Papers (9)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1652 KB)  

    A modification to the adaptive array under the directional constraint [1] is proposed to improve its performance of rejecting wideband interference. By analogy to the pattern synthesis of an antenna array which produces a flat null in its radiation pattern, an additional quantity that corresponds to the derivative of the pattern is generated and combined with the standard feedback quantity to control the weights of the array. This composite system is tested by computer simulation experiments and the following points are demonstrated in contrast to the conventional, simple system: 1) faster adaptation against wideband interference, 2) remarkable improvement of the signal-to-noise ratio of the output, i. e., very small fluctuation. View full abstract»

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  • Sensitivity Discriminating Observer Design for Instrument Failure Detection

    Publication Year: 1980 , Page(s): 460 - 467
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1559 KB)  

    A procedure is presented for the design of a pair of sensitivity discriminating Luenberger observers for instrument failure detection (IFD). The proposed IFD scheme permits detection of instrument malfunctions with reduced sensitivity to process parameter variations. The efficiency of detecting instrument malfunctions and the influence of parameter variations are illustrated with an example. View full abstract»

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  • Sensor Fault Detection in a System with Random Disturbances

    Publication Year: 1980 , Page(s): 468 - 473
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1240 KB)  

    Sensor faults are detected in an operating automatic system by a simplified version of the dedicated observer scheme. Control inputs are augmented by a random disturbance of moderate intensity. The dedicated observer in this case is a Kalman filter, driven by a single sensor. This filter provides estimates of the outputs from the other, nonredundant, sensors. A logical combination of these functionally redundant signals with the actual sensor signals provides prompt detection of incipient faults on all instruments without false alarms. The scheme is applied to a simulation of the lateral axis control system of a hydrofoil boat in which four sensors are to be covered by the fault detection scheme. Tests indicate that the scheme is robust with respect to variations in the intensity of the random disturbance. View full abstract»

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  • Stability and Control of a Trap Mode in Synchronous Orbit

    Publication Year: 1980 , Page(s): 474 - 480
    Cited by:  Papers (1)
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    The possibility of the existence of a trap mode in synchronous orbit is investigated. It is shown that when such a mode exists, certain parameters of the satellite orbit may soon attain undesired equilibrium values, thus complicating the normal stationkeeping operation of the spacecraft. A state-dependent control force which eliminates any such trap mode in the satellite orbit is then investigated. View full abstract»

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  • Sequential Piecewise Recursive Filter for GPS Low-Dynamics Navigation

    Publication Year: 1980 , Page(s): 481 - 491
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2510 KB)  

    The design, implementation, and performance of a real-time estimation algorithm, referred to in this paper as the sequential piecewise recursive (SPWR) algorithm, for the global-positioning system (GPS) low-dynamics navigation system is described. The SPWR algorithm for this application was implemented in single precision arithmetic (32 bit, floating point). Numerical results are presented covariance and filter gains at a slower rate than the state measurement update, and it uses U-D factor formulation to perform covariance computations. The SPWR algorithm saves real-time processing requirements without appreciable degradation of filter performance. Another important feature of the SPWR algorithm is that it incorporates pseudorange and delta-range data from each GPS satellite sequentially for navigation solution. The SPWR algorithm, for this application, was implemented in single precision arithmetic (32 bit, floating point). Numerical results are presented. View full abstract»

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  • Electronic Search Beam Stabilization

    Publication Year: 1980 , Page(s): 492 - 499
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    Compensating for ship's motion (roll and pitch) is a problem fundamental to shipboard radars. The more traditional aproach has been to mechanically stabilize the antenna structure. The alternative approach of stabilizing only the antenna beam is far from being new conceptually, but is more realizable with today's technology. The basic elements are a planar array with an elevation scan capability that rotates continuously in azimuth combined with a high speed digital processor. Electronic stabilization of such an antenna is inherently more challenging than that of a two-axis phase-scanned array. An algorithm is derived for surveillance beam positioning as the antenna rotates. The implementation of this algorithm provides hemispheric search beam stabilization. View full abstract»

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  • Kalman filter design for target tracking

    Publication Year: 1980 , Page(s): 500 - 508
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1205 KB)  

    The problem of solving the matrix Riccati differential equation in the design of Kalman filters for the target tracking problem is considered. An algebraic transformation method is used to reduce the order of the Riccati differential equation and to obtain explicit expressions for the filter gains (in terms of the interceptor /target separation range) which results in a substantial reduction of the computer burden involved in estimating the target states. The applicability of the transform technique is demonstrated for the receiver thermal noise and the target glint noise cases. View full abstract»

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  • Adaptive Main-Beam Nulling for Narrow-Beam Antenna Arrays

    Publication Year: 1980 , Page(s): 509 - 516
    Cited by:  Papers (11)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1903 KB)  

    Narrow-beam, low-sidelobe antennas may be used to enhance communication in the presence of sidelobe interferers. Protection against main-beam interferers as well can be obtained through the use of an adaptive multibeam antenna. Such an antenna, suitable for time-multiplexed, multichannel signals is described here. The objective is to permit successful communication and signal direction-of-arrival tracking in the presence of a large number of sidelobe interferers and a small number of main-beam interferers. View full abstract»

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  • High-Resolution Frequency Measurement by Linear Prediction

    Publication Year: 1980 , Page(s): 517 - 525
    Cited by:  Papers (3)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1907 KB)  

    The efficacy of linear prediction spectrum analysis (LPSA) (also called autoregressive or maximum entrophy spectrum analysis) for problems concerning narrowband signals in noise is examined by means of Monte Carlo simulation. For the case of pure tones (sinusoids) in white noise, both frequency estimation accuracy and resolution of two closely spaced tones with the linear prediction approach are discussed. In addition, estimation of the carrier frequency of a narrowband random (fading) Gaussian signal in noise is considered. The results are compared with standard fast Fourier transform (FFT) methods. These comparisons indicate that there is no significant advantage to using the linear prediction approach with real (bandpass) data. It is concluded that these experiments should be repeated with complex (baseband) data before a complete assessment of the LPS approach can be made. View full abstract»

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  • Information for authors

    Publication Year: 1980 , Page(s): 526
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    Freely Available from IEEE
  • Corrections to "Effect of Sensor Errors on Automatic Gunfire Control,"

    Publication Year: 1980 , Page(s): 527
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  • Corrections to "Microprocessor-Controlled Digital Shunt Regulator"

    Publication Year: 1980 , Page(s): 527 - 528
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  • Corrections to "Crossarray Beamforming with a Parametric Receiving Array and a Line Array"

    Publication Year: 1980 , Page(s): 528 - 529
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  • Corrections to "Certain System Aspects of the Double-Sided Cyclo-Converter"

    Publication Year: 1980 , Page(s): 529
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  • Correction to "Transient Modeling of Synchronous Machine-Transformer-SCR Bridge"

    Publication Year: 1980 , Page(s): 529 - 530
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  • 1980 Pioneer Award

    Publication Year: 1980 , Page(s): 531 - 532
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  • Development of 1000-mHz Distance Measuring Equipment

    Publication Year: 1980 , Page(s): 533 - 540
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    The major radio aids to air navigation are listed. Underlined are those whose signal format is standardized by the International Civil Aviation Organization (ICAO) and they have now all been the subject of the IEEE Aerospace and Electronic Systems Society Pioneer Award, as follows: airborne direction finder/nondirectional beacon (ADF/NDB), Busignies and Moseley, 1959; VHF omnidirectional range (VOR), Stuart, 1962; instrument landing system (ILS), Kramar 1964, Alford 1965; air traffic control radar beacon system (ATCRBS), Williams, Bowden, and Harris, 1973; distance measuring equipment (DME), Dodington, 1980. A brief history of the development of the distance measuring equipment, which also formed the basis for an IEEE National Aerospace Electronics Conference luncheon address, is given. 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