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Aerospace and Electronic Systems, IEEE Transactions on

Issue 6 • Date Nov. 1972

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Displaying Results 1 - 25 of 29
  • Table of contents

    Publication Year: 1972 , Page(s): c1
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  • IEEE Aerospace and Electronic Systems Group

    Publication Year: 1972 , Page(s): c2 - c4
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  • From the Editors

    Publication Year: 1972 , Page(s): 711
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  • An Electrostatic-Wave Topside Sounder

    Publication Year: 1972 , Page(s): 712 - 720
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    An electrostatic-wave topside sounder has been flown to study electron plasma resonances. Unique features of this sounder are the preservation of data spectra, a frequency synthesizer, and a gain-change mechanism. Preservation of the spectra provided frequency information with a resolution of a few hundred hertz by use of a fast Fourier transform while the synthesizer provided the necessary frequency stability. The gain-change mechanism provided information on the strength of the resonances. Resulting data support the electrostatic-wave echo theory of topside resonances. View full abstract»

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  • Distributions of Radar Angels

    Publication Year: 1972 , Page(s): 721 - 727
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1816 KB)  

    A foremost characteristic of large dot radar angels is the wide variation of basic parameter values which they exhibit. This variation is traceable to the nature of the underlying phenomena, i.e., birds and flocks of birds. In this paper, statistical distribution models for the mean radar cross section (RCS) and density of radar angels are obtained, based on a combination of radar and direct ornithological data. The radar cross-section distribution model has been derived from a dimensionless RCS versus wavelength model for individual birds, obtained from measured RCS data which have been scaled to a dimensionless form. This model is applied to ornithological data on populations of birds. The density distribution model is based on statistical reduction of migratory bird data obtained by Lowery's moon watching experiment, and observed seasonal and diurnal variations of radar angel activity. Both resulting distribution models are closely appproximated by the log-normal distribution. The model parameters for these distributions are given. View full abstract»

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  • Radar Altimeter Optimization for Geodesy Over the Sea

    Publication Year: 1972 , Page(s): 728 - 742
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    The optimum processor and its accuracy limit for radar altimetry for geodetic use over the sea are studied with a model accounting for random surface reflectivity, sea height variation, additive noise, and pointing errors, and allowing for arbitrary antenna patterns, signal modulations, and other system parameters. The ¿threshold¿ case solution (which can have any specified accuracy) dictates a signal modulation bandwidth just shy of resolving the sea height variation and/or illuminated sea area (as scaled into time delay and ¿smeared¿ by pointing errors). For such a modulation a relatively complete solution is obtained. These results are used to determine practical radar altimeter designs, additionally accounting for antenna size, stability, and peak power restraints. Conditions allowing neglecting of limiting or complicating effects due to temporally varying reflectivity, sea height, and vehicle position are given and shown to be satisfied for a typical satellite. View full abstract»

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  • Measurement of Distributed Targets with the Random Signal Radar

    Publication Year: 1972 , Page(s): 743 - 750
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2148 KB)  

    A model of a distributed target as a collection of independent, Poisson distributed point scatterers or scattering centers in a range-velocity target space is introduced and is characterized by a deterministic function called the ¿scatterer density function.¿ This function is the density of the point scatterers in the range-velocity space and can be estimated in a relatively straightforward manner by any radar having adequate resolution in both range and velocity and no ambiguities in the region occupied by the distributed target. The use of the random signal radar with a correlator receiver is considered here and the statistical properties of the correlator output, when the return signal is from a distributed target, are derived. It is shown that the spectral density is simply related to the scatterer density function. The technique is illustrated by an example in which the target is a tornado modeled as a cylinder with constant angular velocity. The example suggests that is a possible to remotely estimate the radar cross section per unit volume as a function of distance from the center of the tornado. View full abstract»

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  • The Application of Holography to Sonic Boom Investigations

    Publication Year: 1972 , Page(s): 751 - 756
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    A Q-switch single-mode ruby laser is used for holographic recording of simulated sonic booms. The gaseous objects are visualized by means of the following techniques: 1) Differential interferometry in polarized light, as well as the Schlieren method with defocused phase plate. Both techniques are applied to the holographically recorded wave (directional lighting).2) Interferometry by double exposure with directional lighting. View full abstract»

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  • Probability of Detecting Aircraft Targets

    Publication Year: 1972 , Page(s): 757 - 761
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1191 KB)  

    The statistics of aircraft radar cross section (RCS) are estimated by fitting members of the chi-square family of distributions to empirical distributions obtained from blocks of RCS data, each block of data corresponding to a particular aircraft azimuth aspect. The parameters of the fitted distributions vary with azimuth aspect angle, type of aircraft, and radar frequency. Detection probabilities based on the estimated statistics are calculated and compared with detection probabilities based on Rayleigh statistics. This comparison indicates that the average value of radar cross section has much more effect on probability of detection than the normalized variance of RCS, and in the usual situation tends to mask the effect of the normalized variance on probability of detection. View full abstract»

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  • Constant-Q Pulsed Feedback Electronics for Strapped-Down Gyro Systems

    Publication Year: 1972 , Page(s): 762 - 763
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    A new design is described for support electronics used with rate-integrating gyros in strapped-down operation. By using pulses of constant charge to a linear torquer, system simplicity is retained with accuracy of 40 ppm per year. View full abstract»

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  • Sensitivity Functions for Linear Discrete Systems with Applications

    Publication Year: 1972 , Page(s): 764 - 770
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    z-transform techniques are employed to establish general symmetry and simultaneity properties of the first sensitivity functions of the phase-canonical form of single-input, nth-order, linear, constant, discrete-time, controllable systems. It is demonstrated that computation of the first sensitivity function requires one nth-order model in addition to the system model. This simultaneity property is extended to arbitrary single-input, nth-order, linear, constant, discrete systems. In complete analogy with results presented for continuous systems, symmetry and simultaneity properties may be established for the computation of the /th sensitivity function begin{equation*}^{l}beta^{y} triangleq frac{partial^{l}y_{i}}{partialalpha_{Jl}partialalpha_{Jl-1}cdotspartialalpha_{J2}partialalpha_{J1}}|_{alpha=alpha_{0}} {rm for} substack{i = 1,2,ldots,n\ J_{k} = 1,2,ldots,n\ k = 1,2,ldots,l.}end{equation*} Extension of these results to multi-input systems is also mentioned. The usefulness of the simultaneity property is illustrated by applying the results to the design of a low-sensitivity optimal control law. View full abstract»

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  • Missile Electronic System Hardness Assurance Program

    Publication Year: 1972 , Page(s): 771 - 779
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    A hardness assurance program suitable for a retaliatory or deterrent missile system is discussed. The program consists of three phases: the establishment of suitable controls and screens to ensure piece part hardness, a supplier data monitoring program to measure hardness related parameters in a timely fashion to obtain advanced warning of potential problems, and a hardness assurance verification testing (HAVT) program to periodically measure the radiation response of parts, circuits, subsystems, and systems on a sample basis to ensure proper functioning in simulated radiation environments. All of the data relevant to hardness assurance is stored in computer memory and routinely interrogated with programs which compare current results with the engineering baseline data and other data from preceding lots. Other computer programs enable statistical estimation of system response to the radiation environment with confidence based on the expanding data base provided by the HAVT program. View full abstract»

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  • Stable-Member Mounted Instrument Environment Simulation Model Development

    Publication Year: 1972 , Page(s): 780 - 790
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1657 KB)  

    The equations of motion for the stable member of a threegimbal platform are presented [3]. These equations are combined with models of the three platform control loops to formulate a model for the system. The system model is simplified and a digital simulation is developed for studying the motion of the stable member under conditions of dynamic vehicle angular environment. View full abstract»

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  • FM Laser Noise Effects on Optical Doppler Radar Systems

    Publication Year: 1972 , Page(s): 791 - 799
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2062 KB)  

    A detailed analytical study is made of the effect of FM noise on a laser carrier frequency which is used in a Doppler radar. Both long-term drift and short-term FM noise are considered. The case of high modulation index of the noise is permitted by the theory. Forward as well as slanted beams are examined. Curves have been calculated for each case to allow rapid estimates of the bandwidth requirements to accomodate the laser noise. This, in turn, will give the resolution limit of the radar caused by that noise. A summary of the results is given. View full abstract»

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  • Linear Regression Filtering and Prediction for Tracking Maneuvering Aircraft Targets

    Publication Year: 1972 , Page(s): 800 - 810
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2327 KB)  

    A Cartesian coordinate linear regression filter is utilized for tracking maneuvering aircraft targets. Measurements of target position are made in a line-of-sight coordinate frame, but filtering is performed in Cartesian coordinates. Numerical results are given for optimizing the truncation time constant such that a good balance is obtained between the dynamic errors and the standard deviations. Lower bounds on the dynamic errors are established for the Cartesian coordinate linear regression filter and compared with a line-of-sight coordinate Kalman filter. View full abstract»

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  • On Identifying Transfer Functions and State Equations for Linear Systems

    Publication Year: 1972 , Page(s): 811 - 820
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    Two methods are established for identifying constantcoefficient C2n-type noise-free linear systems if the time response data of the input-output or of all states are known. 2n response data are required to identify an nth-order transfer function or state equation for an unknown linear system. The order of the unknown system can be identified by checking a sequence of determinants. The Z transform and its inversion are mainly used. View full abstract»

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  • A New Approach to Geometry of Range Difference Location

    Publication Year: 1972 , Page(s): 821 - 835
    Cited by:  Papers (65)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2822 KB)  

    Loran, as an example of a ¿hyperbolic¿ range difference location system, provides hyperbolic lines of position on which the target must lie. It is shown in this paper that lines of position need not be hyperbolic, i.e., an exact straight line of position on the plane or the surface of a sphere (where the solution is a great circle) is derived and computer-generated error maps are given. View full abstract»

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  • An Optimal Control Approach to Designing Constant Gain Filters

    Publication Year: 1972 , Page(s): 836 - 842
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1273 KB)  

    This paper applies optimal control theory to designing constant gain filters which minimize a weighted average of the filtered variances. Uniaxial second-order motion is studied in detail, and an example is given which indicates that a constant gain filter may be designed with performance comparable to a Kalman filter. An appendix is included which shows how the approach may be extended to higher order systems. View full abstract»

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  • Raster Scan Track of a Radar Scatterer Ensemble

    Publication Year: 1972 , Page(s): 843 - 850
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1963 KB)  

    A method is discussed for tracking the radar cross-section centroid of an ensemble of scatterers, using a raster scan observation technique. Estimation of the mean-squared dimensions of the ensemble is also considered. A maximum permissible beam separation is defined for the scan. Expressions for the bias and variance of the centroid estimates are given. Advantages of the approach are that individual scatterers need not be resolvable, and that the number of beams is independent of the number of scatterers. View full abstract»

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  • On the Mapping Associated with the Complex Representation of Functions and Processes

    Publication Year: 1972 , Page(s): 851 - 854
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    The mapping between function spaces that is implied by the representation of a real ¿bandpass¿ function by a complex ¿low-pass¿ function is explicitly emphasized. The discussion is extended to the representation of random processes where the mapping is between spaces of random processes. View full abstract»

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  • A Simple Approximate Formula for Glint Improvement with Frequency Agility

    Publication Year: 1972 , Page(s): 854 - 855
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (313 KB)  

    Referring to a previous paper on the subject, this correspondance gives a simple approximate formula for improvement in tracking accuracy that can be obtained by using frequency agility to reduce glint errors. The result turns out to be the smallest of two easily calculated ratios. View full abstract»

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  • Simplified Calculation of a Covariance Given by Levin

    Publication Year: 1972 , Page(s): 855 - 858
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    An expression valid for large values of a signal-to-noise ratio is obtained for the covariance of a particular least squares estimate. The quantity estimated is a vector ¿ embodying the direction and speed of a plane wave impinging upon an array of sensors. The method used for calculation differs from that suggested by Levin [1], is thought to be more straightforward, and yields the same results. View full abstract»

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  • Correction to "An Approach to Fixed-Point Smoothing Problems"

    Publication Year: 1972 , Page(s): 858
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  • Technology and Professional Societies

    Publication Year: 1972 , Page(s): 859 - 867
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  • Table of contents

    Publication Year: 1972 , Page(s): 868
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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