By Topic

Aerospace and Electronic Systems, IEEE Transactions on

Issue 6 • Date Nov 1990

Filter Results

Displaying Results 1 - 14 of 14
  • I-O map inversion, zero dynamics and flight control

    Publication Year: 1990 , Page(s): 1022 - 1029
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    The trajectory control of aircraft in rapid, nonlinear maneuvers is discussed. Based on nonlinear invertibility theory, a control law is derived to independently control roll, pitch, and sideslip angles using rudder, elevator, and aileron. Integral feedback is introduced in order to obtain robustness in the control system to parameter uncertainty. The stability of the zero dynamics is examined. Simulation results are presented to show that in a closed-loop system, precise simultaneous lateral and longitudinal maneuvers can be performed despite the presence of uncertainty in the stability derivatives View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Track formation with bearing and frequency measurements in clutter

    Publication Year: 1990 , Page(s): 999 - 1010
    Cited by:  Papers (67)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (724 KB)  

    Target motion analysis from a narrowband passive sonar that yields bearing and frequency measurements in the presence of false detections (clutter) in a low-SNR (low signal-to-noise ratio) environment is discussed. The likelihood function used to compute the maximum likelihood estimation of the track parameters (localization and frequency) incorporates the false alarms via the probabilistic data association technique. The Cramer-Rao lower bound is calculated and results obtained from simulations are shown to be compatible with it. A test of track acceptance is also presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Equivalent transformation for a partially adaptive array

    Publication Year: 1990 , Page(s): 1031 - 1034
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    A partially adaptive array is one in which elements of a phased array are controlled or adaptively weighted in groups or in which certain elements, called auxiliary elements, are made controllable. Mathematically, this type of array is formed by transforming all of the elements of an array by a nonsquare matrix such that the resulting output vector has a length less than the number of array elements. It is shown that there is an equivalent matrix transform that can effectively be utilized in analyzing the partially adaptive array's performance when a small number of external jammers are present. Processor implementation and convergence rate considerations lead to the desirability of reducing the dimensionality of the cancellation processor while maintaining good sidelobe interference protection. A meaningful measure of canceller performance is to compute the optimal output signal-to-noise ratio. This expression is a function of the jammer, direction-of-arrival vectors (DOAVs), jammer powers, the array steering vector, and internal noise. It is shown that if this expression is computed for the fully adaptive array then it is easily computed for the partially adaptive array by transforming the jammer DOAVs and the steering vector by the orthogonal projection matrix defined by the rows of the subarray transformation matrix and substituting these vectors back into the original expression for the fully adaptive array View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimal FIR filters for time-varying state-space models

    Publication Year: 1990 , Page(s): 1011 - 1021
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB)  

    An optimal FIR (finite impulse response) filter and smoother is introduced for the time-varying state-space model. The suggested filter has an FIR structure and utilizes finite observation. It is shown that the impulse response of the optimal FIR filter can be obtained by a simple Riccati-type matrix differential equation. Especially for time-invariant systems, this FIR filter reduces to previously known simple forms. For implementation, a recursive form of the optimal FIR filter and smoother is derived by using adjoint variables, and computational algorithms are suggested. It is also shown by sensitivity analysis that the proposed optimal FIR filter alleviates potential divergence characteristics of the standard Kalman filter View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Parameter identification for state-space models with nuisance parameters

    Publication Year: 1990 , Page(s): 992 - 998
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    The problem of identifying parameters in a dynamic model is considered based on the premise that certain parameters not being estimated are not known precisely. A procedure is described for accounting for these imprecisely known nuisance parameters when estimating the primary parameters of interest. The technique uses the asymptotic normality of the estimate together with the implicit function theorem to determine a correction to the estimate uncertainty evaluated from the Fisher information matrix. Efficient evaluation of the correction using Kalman filters is discussed and a numerical example for the X-22A aircraft is presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Use of idempotent matrices to validate linear systems software

    Publication Year: 1990 , Page(s): 935 - 952
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1252 KB)  

    In seeking to verify various computer implementations of Kalman filters, the extended Kalman filter (EKF), or other algorithms that rely on the same fundamental computations in a variety of different applications, it is useful to first validate software performance using low-dimensional test problems of known solution. Besides reporting the state-of-the-art in computing the critical fundamental linear system building blocks in a simple manner that is easy to understand, the author describes the easy construction of nontrivial test cases of known solution, provides a rigorous demonstration of how to augment/concatenate several low-dimensional test problems of known solution to comprise a higher-dimensional system of known solution that is also to be used in software test and validation/verification, and presents the computation of a closed-form exact optimal control solution that can also be used to validate software View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reconciling steady-state Kalman and alpha-beta filter design

    Publication Year: 1990 , Page(s): 986 - 991
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    The deterministic design of the alpha-beta filter and the stochastic design of its Kalman counterpart are placed on a common basis. The first step is to find the continuous-time filter architecture which transforms into the alpha-beta discrete filter via the method of impulse invariance. This yields relations between filter bandwidth and damping ratio and the coefficients, α and β. In the Kalman case, these same coefficients are related to a defined stochastic signal-to-noise ratio and to a defined normalized tracking error variance. These latter relations are obtained from a closed-form, unique, positive-definite solution to the matrix Riccati equation for the tracking error covariance. A nomograph is given that relates the stochastic and deterministic designs View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Nonparametric rank detectors on quantized radar video signals

    Publication Year: 1990 , Page(s): 969 - 975
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    Uniform randomization of ties is required for defining distribution-free ranks of independent and identically distributed quantized samples. Formulas of rank probabilities are given and applied to radar detection under quantized video samples. For some detectors, and assuming Gaussian noise, the asymptotic loss L(q) is calculated versus the normalized quantization step q, and the loss L(q) is estimated by Monte Carlo simulations. Both of these resulted in monotonic functions of q (0<q<1.1) that are independent of the other parameters. Furthermore, L(q)≈L(q )⩽0.45 dB, as q<0.8. The quantization step q is normalized with respect to the noise standard deviation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A recursive method for calculating binary integration detection probabilities

    Publication Year: 1990 , Page(s): 1034 - 1035
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    The calculation of the probability of detection for a binary integration when the probability of a threshold crossing changes from sample to sample is presented. The significance of the algorithm is that it uses a simple recursion relation which provides a computationally efficient means of performing the calculation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Sensitivity analysis of the maximum likelihood direction-finding algorithm

    Publication Year: 1990 , Page(s): 953 - 968
    Cited by:  Papers (32)  |  Patents (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1272 KB)  

    A first-order analysis is performed of the sensitivity of the maximum likelihood (ML) direction-finding algorithm to system errors which cause differences between the array manifold used by the algorithm and the true array manifold. The effect of such errors on the directions-of-arrival (DOA) estimates is investigated. The ability of the ML algorithm to resolve two closely spaced sources in the presence of phase and gain errors in the array elements or in the receivers, or errors in the element locations, is analyzed. A formula for computing the failure threshold of the algorithm as a function of source separation and other system parameters is derived and tested by simulation. The analysis assumes that the exact covariance matrix of array element outputs is known View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Identification of rational transfer function from frequency response sample

    Publication Year: 1990 , Page(s): 925 - 934
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    A method for identifying a transfer function, H(z)=A(z)/B(z), from its frequency response values is presented. Identifying the transfer function involves determining the unknown degrees and coefficients of the polynomials A(z) and B( z), given the frequency response samples. The method for finding the parameters of the transfer function involves solving linear simultaneous equations only. An important aspect of the method is the decoupled manner in which the polynomials A(z) and B(z) are determined. The author presents two slightly different derivations of the linear equations involved, one based on the properties of divided differences and the other using Vandermonde matrices or, equivalently, Lagrange interpolation. A matrix synthesized from the given frequency response samples is shown to have a rank equal to the number of poles in the system View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of Min-Norm and MUSIC with arbitrary array geometry

    Publication Year: 1990 , Page(s): 976 - 985
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB)  

    A nonasymptotic performance comparison is presented between the Min-Norm and MUSIC algorithms for estimating the directions of arrival of narrowband plane waves impinging on an array of sensors. The analysis is based on a finite amount of sensor data. The analysis makes the assumption of high signal-to-noise ratio (SNR), and it applies to arrays of arbitrary geometry. It is shown that Min-Norm can be expressed as a certain data-dependent weighted MUSIC algorithm, and that this relationship allows a unified performance comparison. It is also shown that the variances of the estimated directions-of-arrival from the MUSIC algorithm are always smaller than those of the Min-Norm algorithm at high SNR when both algorithms employ a numerical search procedure to obtain the estimates View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Radar/sonar acceleration estimation with linear-period modulated waveforms

    Publication Year: 1990 , Page(s): 914 - 924
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (772 KB)  

    Doppler and acceleration tolerance of wideband LPM/HFM (linear period-modulated, hyperbolic frequency-modulated) and linear frequency-modulated (FM) signals are compared. A bank of filters matched to frequency-shifted versions of a wideband LPM/HFM transmission system yields a joint maximum likelihood estimate of range and acceleration and avoids acceleration-induced degradation in detection performance. Analytical and neurophysiological results suggest that such processing can be used in bat echolocation for detection and classification of insect wing motion since wideband LFM waveforms are much less Doppler-tolerant than HFM waveforms but have greater acceleration tolerance View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Frequency hop multiple access codes based upon the theory of cubic congruences

    Publication Year: 1990 , Page(s): 1035 - 1039
    Cited by:  Papers (18)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    The need for families of frequency-hop codes which have mutually small auto-ambiguity and cross-ambiguity functions is discussed. Current coding methods are reviewed. A new family of frequency-hop codes based upon the number-theoretic concept of cubic congruences is introduced. It is shown that for about 50% of the prime numbers, families of full codes exist which have at most two coincidences for any time-frequency shift in their auto-ambiguity functions and at most three coincidences in the set of mutual cross-ambiguity functions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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