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Aerospace and Electronic Systems, IEEE Transactions on

Issue 4 • Date July 1971

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Displaying Results 1 - 25 of 40
  • Table of contents

    Page(s): c1
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    Freely Available from IEEE
  • IEFE Aerospace and Electronic Systems Group

    Page(s): c2
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    Freely Available from IEEE
  • From the Editors

    Page(s): 577
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    Freely Available from IEEE
  • The Engineer as a Radical?

    Page(s): 578 - 584
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    Outdated and rigorous curricula are not only producing engineers unsuited to the challenges of the 1970's, but they are scaring off many of the most creative and intelligent students. Engineering education has become an endurance test; the excitement has been lost. Most students strive only to get out. Engineering schools have not yet realized the importance of the involvement of engineers in current environmental problems. They continue to present only the dry technical courses and seem unconcerned about the student's sense of social perspective or his motivation. This paper proposes a freshman awareness seminar plus project oriented learning in the following years as a remedy for this sad situation. View full abstract»

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  • A Practical Method of Maintainability Allocation

    Page(s): 585 - 589
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    A practical method of allocating the system maintainability (M) requirement to lower functional equipment levels is described. The use of this method minimizes trial and error in establishing values for each equipment item and the amount of tradeoffs required in apportionment relative to equipment complexity and M design characteristics. It has flexibility in application in that it can provide initial allocations at the conceptual design stage and updated allocations at various stages of design when more is known about a given system. The method will prove practical if the system requirement is practical and if the basic k factor tables are reasonably correct. If the system requirement is unrealistic, no method of allocation could make it realistic. View full abstract»

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  • Telecommunications Technology in Metropolitan Areas

    Page(s): 590 - 594
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    The electronic communication technology available today offers the possibility of changing many patterns of information transfer in urban areas. There are three major trends which are converging to make this change possible. These are: 1) the technology to permit wideband information transfer manifested in the existing 2300/CATV/Cable System and in modification of the Bell network for wideband services; 2) the potential demand for a vast range of new services to persons operating in the urban areas; 3) the increasing demands for meeting mobile information transfer needs in the urban areas through radio systems operating in the 100 to 1000 MHz part of the spectrum. The extent to which these trends are allowed to converge will be a function of the quality of telecommunication policy formulation and execution. In order to formulate policy, it is necessary to have a vision of the future toward which to work. This paper will discuss the types of services possible with the technology presently available, which will have impact on future policy decisions. View full abstract»

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  • Summary of European Solar Cell Activities

    Page(s): 595 - 605
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    A review of activities in the solar cell field by the European manufacturers and agencies is presented. These activities include considerable efforts in research, development, and production of solar cells, covers, and solar cell arrays. Details of the qualification and use of European cells and covers on the Intelsat IV program are presented. View full abstract»

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  • Structural Failures in Light-weight Solar Cell Arrays under Thermal Cycling

    Page(s): 606 - 612
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    Several different types of small silicon solar cell arrays mounted on lightweight honeycomb panels and on flexible substrates were subjected to long-term thermal cycling tests between -160 and 600C in dry nitrogen. Other tests included immersion in liquid nitrogen and vibration fatigue tests in excess of one million cycles. The arrays experienced a reduction in output caused by contact failure, fracture in the silicon and cover slide, and disintegration of the honeycomb. Failure modes caused by different cell and interconnect constructions are compared. View full abstract»

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  • Parameter Optimization of a Nutation Damper Via the Second Method of Liapunov

    Page(s): 613 - 616
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    The principle of parameter optimization of a linear time-invariant system via the second method of Liapunov is applied to optimize the parameters of a nutation damper suggested recently. Numerical results are derived, and it is indicated that the present values of optimum parameters agree closely with those obtained earlier by an approximate method. View full abstract»

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  • Error Analysis of Space-Stable Inertial Navigation Systems

    Page(s): 617 - 629
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    The error equations for a space-stable inertial navigation system are derived. This is done by directly perturbing the mechanization equations in the inertial frame and then transforming in open-loop fashion to the local-level frame. A rotating inertial platform and velocity and altitude damping are considered. The relations between errors in space-stable and local-level systems are noted. Numerical results are presented for certain random error sources. View full abstract»

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  • Resolution in Doppler and Acceleration with Coherent Pulse Trains

    Page(s): 630 - 636
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    The resolution properties and clutter performance of a simultaneous Doppler and acceleration measurement are investigated in detail with particular emphasis given to coherent pulse trains. The analysis is based on the concept of a matched-filter receiver, although receiver weighting of the type that reduces Doppler sidelobes is also analyzed in detail. Near the main lobe of the acceleration response is a pedestal-ike sidelobe region, the height of which is about 1/N of the main response lobe power where N is the number of pulses in the train. The extent of this pedestal along the acceleration axis is proportional to N. The acceleration measurement in a clutter environment is best performed when both targets and clutter are confined to this pedestal region, since some response sidelobes outside of this region are extremely large. View full abstract»

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  • A qualitative study of proportional navigation

    Page(s): 637 - 643
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    This paper represents a study of the trajectories of an ideal missile homing on a target according to the proportional navigation law. A qualitative study is performed and conditions are determined which enable one to demonstrate that: 1) the missile always reaches the target regardless of the initial conditions at launch; 2) the rotational rate of the line of sight is decreasing at the pursuit end. View full abstract»

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  • Ideal Limiting of Periodic Signals in Random Noise

    Page(s): 644 - 651
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    A method based on Hermite polynomials is developed for analysis of the output resulting from passing Fourier expandable signals and noise through general zero-memory devices. New results are developed for the output time and autocorrelation functions. Special results are generated for an ideal clipper. Techniques for obtaining results for practical cases are discussed. The method itself can be modified and applied to non-Gaussian noise and general nonlinear devices with nondeterministic signals. View full abstract»

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  • An Optimum Phase Synchronizer in a Partially Coherent Receiver

    Page(s): 652 - 661
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    The derivation and the statistical properties of the maximum a posteriori probability phase estimator of a sinusoidal signal in white Gaussian noise are considered. The probability density function of the phase estimate is developed. The estimator efficiency and performance as a phase synchronizer in a partially coherent receiver are calculated and compared with a first-order phase-locked loop phase estimator. View full abstract»

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  • A New Sampling Procedure for the Synthesis of Linear Transversal Filters

    Page(s): 662 - 670
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    In linear transversal filters for signal processing, the impulse response of the filter is syntheszed in a sampled form by means of a tapped delay line with weighted and summed taps. The synthesis procedure consists of sampling the specified impulse response at appropriate intervals and using the sample values as the tap weights. A nonuniform sampling procedure for the synthesis of the impulse response is introduced, which can produce results more conveniently than the classical Shannon sampling procedure because of the simplicity of the transversal filter implementation. According to the new procedure, in the time domain the samples are taken at points where the instantaneous phase of the impulse response is a multiple of ir radians. The spectral distribution which ensues in the frequency domain consists of a series of spectra all having the same fractional bandwidth. The transversal filters synthesized by this sampling criterion are referred to as phase-sampled impulse response (PSIR) filters. An important application of PSI R filters is to the generation and matched filtering of a large class of AM and FM waveforms. View full abstract»

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  • Recursive Methods for Computing Detection Probabilities

    Page(s): 671 - 676
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    Recursive methods are drived for computing detection probabilities for general fluctuating targets in Gaussian noise. For the generalized chi-square family of fluctuating targets, very simple and convenient recursive algrithms result. The methods are also extended to cell-averaging CFAR. Although the detection probability is expressed iw: terms of an infinite series, a convenient expression is derived for the resulting error when the series is truncated. Cell-averaging CFAR results are computed for nonfluctuating, Swering case I, and Swerling case II fluctuating targets. View full abstract»

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  • Resolution Performance of Pulse Trains with Large Time-Bandwidth Products

    Page(s): 677 - 685
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    The coherent pulse train has good clutter suppression performance because the energy in its matched-filter response is essentially concentrated within sharp ambiguous spikes. However, this is so only when the Doppler distortions are neglected, so that the Doppler effect is taken as a simple translation of the carrier frequency. This paper analyzes the consequences of Doppler distortions on the resolution performance of pulse trains. It is found that Doppler distortions widen the Doppler ambiguities of the pulse train response, with the widening factor proportional to the order of the Doppler ambiguity. This reduces the interval between Doppler ambiguities, and hence the Doppler width of a clutter space that can be accommodated without severe clutter interference. For an operation in a Doppler-ambiguous mode, it also degrades nominal Doppler resolution performance. A detailed analysis of the effects is presented, and numerical results on the widening of the Doppler ambiguities are obtained. View full abstract»

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  • A Self Bit Synchronizer Matched to the Signal Shape

    Page(s): 686 - 693
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    A suboptimum self bit synchronizer is considered that matches the signal shape, i. e., operates making a clever use of the knowledge of the signaling waveform. The noise performance of this system is analyzed for high signal-to-noise ratios, and an expression is obtained for the variance of the timing errors. This variance is compared with that of systems proposed by other authors on the basis of equal closed-loop noise bandwidth and equal signal shape. It is found that the use of this matched synchronizer enables appreciable timing jitter reductions. View full abstract»

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  • Comments on the 1970 Pioneer Award

    Page(s): 694 - 696
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  • Comments on the 1970 Pioneer Award

    Page(s): 696 - 697
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  • Effect of Envelope Limiting in Adaptive Array Control Loops

    Page(s): 698 - 700
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    The properties of an adaptive array antenna, including transient response rate and control loop noise, depend on the intensity of the external noise field. This dependence can be reduced by envelope hard limiting in the control loops, without degrading the performance of the adaptive array. View full abstract»

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  • The Effect of Aircraft Lateral Dynamics on Aircraft Positioning Accuracy When Using Loran-C

    Page(s): 700 - 704
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    The dynamics of an aircraft following a fixed course line using Loran-C for position fixing are shown to interact with Loran-C receiver dynamics to result in cross-track aircraft positioning errors that are smaller than cross-track Loran receiver errors. In a particular case considered, this error reduction is on the order of 50 percent. View full abstract»

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  • The Detection Performance of the Siebert and Dicke-Fix CFAR Radar Detectors

    Page(s): 706 - 709
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    The Siebert and the Dicke-fix CFAR radar detectors, used to maintain a constant false alarm rate (CFAR) in radar receivers under very similar circumstances, are considered. The Siebert detector represents the maximum-likelihood detection procedure for a signal in Gaussian noise of unknown power level, whereas the Dicke-fix makes use of a bandpass limiter to normalize the input and thus ensure a constant false alarm rate. The detection performance of the two detectors is determined and a comparison shows that over a wide range of parameters, the Dicke-fix introduces a loss which is approximately 1 B larger than for the Siebert detector. 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.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Lance Kaplan
Army Research Laboratory