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Aerospace and Electronic Systems, IEEE Transactions on

Issue 2 • Date March 1976

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Displaying Results 1 - 25 of 40
  • Table of contents

    Publication Year: 1976 , Page(s): c1 - 312-b
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    Freely Available from IEEE
  • IEEE Aerospace and Electronic Syatems Society

    Publication Year: 1976 , Page(s): c2 - 312a
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    Freely Available from IEEE
  • From the Editors

    Publication Year: 1976 , Page(s): 97
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    Freely Available from IEEE
  • Adaptive Pulse Doppler Ambiguity Resolution

    Publication Year: 1976 , Page(s): 98 - 103
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1458 KB)  

    This paper demonstrates and tests a new algorithm for extracting velocity information from a pulse Doppler radar signal. The system is adaptive and performs weil in the presence of target scintillation. This paper also shows a special steady-state version of the adaptive algorithm. lt is computationally attractive and produces near optimal velocity estimates. View full abstract»

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  • The High Power Metal-Oxide Varistor as a Vehicular and Aircrcraft Transient Suppessor

    Publication Year: 1976 , Page(s): 104 - 108
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3410 KB)  

    The shunt-type transient suppressor currently being used by the U.S. Army for suppression of voltage transients in tactical and combat vehicles is applicable to military aircraft as well. Advances in metal-oxide varistor technology have led to the development of a low-cost, low-voltage device having a breakdown voltage designed for use in 28-V dc electrical systems. This paper discusses the avalanche diode and the metal-oxide varistor as high-power transient suppressors. lt shows that the metal-oxide varistor has a less effective voltage clamp at the required breakdown level of 33 to 36 volts. View full abstract»

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  • An Aircraft Noise Pollution Model for Tra jectory Optimization

    Publication Year: 1976 , Page(s): 109 - 116
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1416 KB)  

    The mobility of our society makes effective and efficient operation of our air terminals a necessity. For this reason, landing trajectories must be optimized. One important factor in the performance index is aircraft noise received by people residing near the terminal. This paper develops a mathematical model of this noise effect so that it may be included in the performance index. The model yields the boundary on the ground inside of which the noise level is at or above 70 dB. This area can be weighted with the population density. The model compares very favorably with available data. View full abstract»

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  • The Detection of Moderately-Fluctuating Rayleigh Targets

    Publication Year: 1976 , Page(s): 117 - 126
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2193 KB)  

    Pulse train detection of fluctuating targets whose coherence time is long compared to the time between pulses and short compared to the pulse train duration is compared for two systems: (1) a recursive digital optimal receiver operating in conjunction with a coherent pulse train transmitter, and (2) a good (but not optimal) receiver operating with a block coherent frequency-hopping transmitter. The equivalence of this type of problem to noise-in-noise detection problems is demonstrated, the performance relations for both systems are derived and comparisons are made. View full abstract»

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  • Demodulator Structures for Pulse-Frequency-Modulated Signals

    Publication Year: 1976 , Page(s): 127 - 130
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    Minimum mean-square-error demodulators for pulse-frequency-modulated signals are considered. The optimum demodulator structure is found and a suboptimum one is proposed that may be implemented by standard circuitry. View full abstract»

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  • Fast-Adapting Matrix Filtering

    Publication Year: 1976 , Page(s): 131 - 139
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1934 KB)  

    Implementation and convergence of adaptive processors are of continuing interest. To this end, a fast-adapting, linear, general recursive matrix-filtering algorithm is described. Two complex xoefficients are optimized at each recursion. A signal and interference estimation procedure is included. Results for some low-resolution, frequency domain beamformer trials with two targets, and using a single sample set, are presented. Considerable adaptive improvement occurs, along with target resolution, compared with a correlation beamformer. The algorithm shows rapid and direct convergence. View full abstract»

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  • Graphical Interpretation of Chirp Echoes from Complex Targets

    Publication Year: 1976 , Page(s): 140 - 145
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1495 KB)  

    Echoes from complex targets due to chirp waveforms show different time responses for different chirp rates, because of the ambiguity of range and radial velocity information. A graphical method is described which enables the derivation of the time response for an arbitrary chirp rate when the scattering cross-section distribution in the range and radial velocity plane is known for complex targets. The graphical method can also be used to generate an approximately realistic scattering cross-section distribution when the time responses for two different chirp rates are given. An example is shown which applies to the computer simulation of the radar echo from a waking reentry space vehicle. View full abstract»

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  • On the Convergence of Iterative Orthogonalization Processes

    Publication Year: 1976 , Page(s): 146 - 151
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1524 KB)  

    Polar decomposition of matrices is used here to investigate the convergence properties of iterative orthogonalization processes. It is shown that, applying this decomposition, the investigation of a general iterative process of a certain form can be reduced to the investigation of a scalar iterative process which is simple. Three known iterative orthogonalization processes, which are special cases of the general process, are analyzed, their convergence rate (order) is determined, and their range of convergence is established in terms of the spectral radius of the modulus of the matrix which is being orthogonalyzed. View full abstract»

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  • Horizon Profile Checkpoints for Low-Altitude Aircraft

    Publication Year: 1976 , Page(s): 152 - 161
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2561 KB)  

    A technique for utilizing on-board sensed horizon profiles and computer stored reference horizon profiles to provide navigation checkpoints for low-altitude aircraft is described. The technique has been analyzed using digitized terrain data and computer simulations to select the best method of horizon profile comparison, to determine horizon data density requirements, and to provide performance comparisons, system error limitations, and tradeoffs. Results of these analyses are shown to support feasibility conclusions and system parameter tradeoffs. View full abstract»

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  • Design of the HEAO Main Bus Shunt Regulator

    Publication Year: 1976 , Page(s): 162 - 172
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2622 KB)  

    The High Energy Astronomy Observatory (HEAO) main bus regulator contains a redundant error amplifier (REA) and a 12-section sequenced shunt transconductance amplifier (STA) in which not more than three and not less than one shunt section are in an active control mode regardless of a failure in any one of the twelve sections. The part of the work concerned with the shaping of the frequency response of the REA and STA minor feedback loops and of the teolator major feedback loop is described. Emphasis is on the application of a general design technique embodying a "design-analyze-measure iteration loop," in which a first-cut design and analysis is corrected ard improved after experimental observation of discrepancies and deficiencies. In particular, an incipient high-frequency oscillation was thereby reliably eliminated. It is demonstrated that analysis techniques involving a minimum of algebra can provide full quantitative information on an efficient and reliable system design. View full abstract»

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  • Bounds on Probability of Error in Decision Feedback Equalizers

    Publication Year: 1976 , Page(s): 173 - 178
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1313 KB)  

    Evaluation of the probability of error in decision feedback equalizers is difficult due to the presence of a hard limiter in the feedback path. This paper derives the upper and lower bounds on the probability of a single error and multiple error patterns. The bounds are fairly tight. The bounds can also be used to select proper tap gains of the equalizer. View full abstract»

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  • Angle Estimation with Adaptive Arrays in External Noise Fields

    Publication Year: 1976 , Page(s): 179 - 186
    Cited by:  Papers (43)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1836 KB)  

    A method of estimating the angle of arrival of a signal at an array of sensors in an external noise environment is outlined. The development is based on a maximum likelihood estimator and leads naturally to adaptive sum and difference beams which null the external noise sources. An algorithm for estimating angle of arrival, based on the outputs of adaptively distorted sum and differnce beams, is shown to perform well in the presence of sidelobe and/or main beam interference. View full abstract»

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  • Position-Location Solutions by Taylor-Series Estimation

    Publication Year: 1976 , Page(s): 187 - 194
    Cited by:  Papers (345)  |  Patents (51)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1524 KB)  

    Taylor-series estimation gives a least-sum-squared-error solution to a set of simultaneous linearized algebraic equations. This method is useful in solving multimeasurement mixed-mode position-location problems typical of many navigational applications. While convergence is not proved, examples show that most problems do converge to the correct solution from reasonable initial guesses. The method also provides the statistical spread of the solution errors. View full abstract»

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  • Constrained Least-Squares Synthesis of Coefficients for Arrays of Sensors and FIR Digital Filters

    Publication Year: 1976 , Page(s): 195 - 202
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1703 KB)  

    A general method is presented for synthesizing weighting coefficients for arrays of sensors or for finite-impulse-response (FIR) digital filters. The beam pattern of the array or the frequency response of the digital filter is a weighted, least mean-square (LMS) approximation to a desired function, subject to constrained pattern values at specified points. The method is applied to the problem of producing beam patterns of a line array for the rejection of interfering point sources. For this case, we show that adaptive array processing can be based on modification of the roots of the array polynomial. View full abstract»

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  • Exact Target Angular Coordinates from Biased Radar Measurements

    Publication Year: 1976 , Page(s): 203 - 209
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    Exact and simplified expressions are derived for the calibration of raw target coordinate measurements obtained from a tracking radar, The measured target position in angle is indicated by the displacement of the antenna boresight. The true target position, however, deviates from this measured value because of such system biases as tilt (leveling error), nonorthogonality of axes, collimation error, dynamic lag, etc. These and other biases are accounted for in this paper. The pedestal configuration assumed is an elevation over azimuth mount. A noise-free environment is also assumed. View full abstract»

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  • Suboptimal Simulation and Suppression of Clutter Signals

    Publication Year: 1976 , Page(s): 210 - 212
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (883 KB)  

    Two digital filters are presented, which are suited for generating (Correlation) or suppressing (decorrelation) by approximation time-discrete signals with preset autocorrelation function from white noise. The advantage of these suboptimal filters is that the determination of their coefficients is very simple. For this reason the filters are weil suited for generating or suppresing signals with rapidly varying statistical parameters. One application possibility is the simulation and the adaptive suppression of clutter signals in surveillance radar systems. View full abstract»

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  • Pull-In Behavior of Third-Order Generalized Phase-Locked Loops

    Publication Year: 1976 , Page(s): 213 - 218
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1115 KB)  

    This paper analyzes third-order phase-locked loops with an arbitrary phase-detector characteristic and imperfect integration by the quasi-stationary approach with a suitable linearization of the non-linear differential equation deseribing the loop behavior; ideal integration is also considered. The main feature of this technique is the use of an easy mathematical approach which allows a direct physical insight into acquisition behavior and the development of simple expressions for the time and pull-in range. View full abstract»

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  • Comparison of Bit Synchronization Schemes Using AM and Summed Clocks

    Publication Year: 1976 , Page(s): 219 - 224
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    This paper considers bit synchronization through the use of a separate clock signal which is either amplitude modulated onto or summed with the data signal. For continuous data transmission, such schemes are known to be inferior, in the sense of efficient use of power, to schemes which derive synchronization directly from the data signal. However, these techniques have application in burst systems such as spacecraft command systems, and in systems where receiver simplicity is more important than power conservation. For systems in which the composite data-clock signal subsequently modulates an RF carrier, it is shown that the summed clock signal performs slightly better than the AM clock signal, and that for both signal types, the optimum allocation of power between data and clock is approximately 9:1. View full abstract»

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  • Programmed-Amplitude Binary Signaling with Decision and Information Feedback

    Publication Year: 1976 , Page(s): 225 - 229
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1252 KB)  

    A sequential detection scheme with combined decision and information feedbacks, where the signal amplitude at each iteration may be properly programmed, is analyzed. This approach allows a remarkable gain in transmission rate and a significant reduction in the peak-to-average power ratio, relative to the nonsequential scheme with constant signal amplitude. View full abstract»

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  • Harmonic Radar Systems for Near-Ground In-Foliage Nonlinear Scatterers

    Publication Year: 1976 , Page(s): 230 - 245
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3448 KB)  

    The radar transmission equation for a harmonic radar operating over a planar, finite dielectric Earth through foliage is derived for an interesting class of nonlinear scatterers. The received power can typically depend on range to the (-14) power for small objects near the ground. The maximum detection range of a ground-based system is related to all major system parameters: it is most sensitive to polarization, transmit antenna height, and transmit wavelength; moderately sensitive to transmit power and transmit antenna area; and least sensitive to receive antenna area, harmonic scattering cross section, and mode of data processing. For example, there is seen to be a best apportionment of total available aperture area into disjoint transmit and receive apertures which can be well approximated by the equal gain condition. Also, there is seen to be a critical path distance through foliage; at distances less than this, small wavelengths are desirable and, conversely, the upper transmit frequency limit may be set by nonlinear scatterer response. Airborne synthetic aperture radar systems are discussed and quantification of harmonic noise and effects of scatterer fluctuation are made. A useful phenomenological model of a nonlinear scatterer is given that is consistent with some observations and predicts a frequency dependence. Nonlinear scatterer effects on range resolution are discussed. View full abstract»

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  • A Correlation Polarimeter for Noise-Like Signals

    Publication Year: 1976 , Page(s): 246 - 254
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    Optimum estimation (tracking) of the polarization plane of a linearly polarized electromagnetic wave is determined when the signal is a narrow-band Gaussian random process with a polarization plane angle which is also a Gaussian random process. This model is Compared to previous work and is applicable to space communication. The estimator performs a correlation operation similar to an amplitude -comparison monopulse angle tracker, giving the name correlation polarimeter. Under large signal-to-noise ratio (SNR), the estimator is causal. Performance of the causal correlation polarimeter is evaluated for arbitrary SNR. Optimum precorrelation filtering is determined. With low SNR, the performance of this system is far better than that of previously developed systems. Practical implementation is discussed. A scheme is given to reduce the effect of linearly polarized noise. View full abstract»

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  • Moving Emitter Classification

    Publication Year: 1976 , Page(s): 255 - 269
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2596 KB)  

    One of the problems that plague emitter location systems is the presence of data from emitters that are in motion. If this motion is not detected, erroneous location estimates and filled data files result. An algorithm to classify an emitter as moving or stationary is presented along with extensive illustrations and results based upon simulated data. 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