By Topic

Aerospace and Electronic Systems, IEEE Transactions on

Issue 1 • Date Jan 1998

Filter Results

Displaying Results 1 - 25 of 33
  • Interference experiments between fixed-satellite and terrestrial radio-relay services

    Publication Year: 1998 , Page(s): 23 - 32
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1300 KB)  

    To resolve interference problems between fixed-satellite and terrestrial radio relay services and expand coordination areas between the two services, theoretical and experimental studies were carried out. Theoretical D/U values calculation formulas between the two systems were derived, interference data from 4 GHz and 11 GHz band terrestrial radio-relay systems were obtained by a measuring system mounted on a vehicle. By comparing those results, it becomes clear that the ensemble interference reduction factors for 4 GHz and 11 GHz bands are around 20 dB, which is mixed values of attenuation and reflection from big buildings in urban areas View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Target tracking with a network of Doppler radars

    Publication Year: 1998 , Page(s): 33 - 48
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1380 KB)  

    By observing a Doppler signal at several points in space, it is possible to determine the position, velocity, and acceleration of a moving target. Parameter identification for a constant-acceleration motion model is studied, and the Cramer-Rao bound on motion parameter uncertainty is obtained for phaseand frequency-based estimation strategies, with the result that the preferred strategy depends upon the sensor/target geometry and target motion. Direct identification of the constant-acceleration trajectory model from the Doppler signal requires a 9-dimensional nonlinear optimization. Exploiting symmetry in the sensing geometry, a novel trajectory representation is presented which reduces the nonlinear optimization to one in 3 dimensions, with additional parameters obtained by linear identification. Baseball tracking using a network of four Doppler radars is experimentally demonstrated View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Phase-only LMS and perturbation adaptive algorithms

    Publication Year: 1998 , Page(s): 169 - 178
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (752 KB)  

    The author defines a phase-only gradient-based adaptive algorithm analogous to the least mean square (LMS) algorithm. Two phase-only perturbation algorithms are then defined. It is shown that the gradient for the perturbation algorithms can be obtained by cross-correlating binary perturbation sequences, that are applied to the adaptive phases, with the resulting instantaneous output power or voltage. It is also shown that a single set of phase-only adaptive weights can be used to simultaneously null interference in multiple output beams. Simulation results are presented for all of the new algorithms. The phase-only perturbation techniques eliminate the need for element level receivers and support low cost retrofitting of adaptive nulling on phased arrays by using conventional beamsteering circuits to apply the adaptive weights View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On-board regeneration of uplink signals using a blind multichannel estimator

    Publication Year: 1998 , Page(s): 49 - 62
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1092 KB)  

    We propose a restoration method to compensate distortions caused by cross-polarization interference (CPI) and multipath propagation when multichannel transmission is employed in the uplink of an on-board-processing (OBP) satellite. The proposed baseband signal processing architecture is numerically robust and efficient as vector operations are avoided by efficient orthogonal transformations. Since the algorithm is based on higher-than-second-order statistics, the method is very effective in severe distortion conditions where a traditional, perfectly trained Kalman multichannel filter obtains poor performance View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Bearings-only tracking for maneuvering sources

    Publication Year: 1998 , Page(s): 179 - 193
    Cited by:  Papers (22)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1164 KB)  

    Classical bearings-only target-motion analysis (TMA) is restricted to sources with constant motion parameters (usually position and velocity). However, most interesting sources have maneuvering abilities, thus degrading the performance of classical TMA. In the passive sonar context a long-time source-observer encounter is realistic, so the source maneuver possibilities may be important in regard to the source and array baseline. This advocates for the consideration and modeling of the whole source trajectory including source maneuver uncertainty. With that aim, a convenient framework is the hidden Markov model (HMM). A basic idea consists of a two-levels discretization of the state-space. The probabilities of position transition are deduced from the probabilities of velocity transitions which, themselves, are directly related to the source maneuvering capability. The source state sequence estimation is achieved by means of classical dynamic programming (DP). This approach does not require any prior information relative to the source maneuvers. However, the probabilistic nature of the source trajectory confers a major role to the optimization of the observer maneuvers. This problem is then solved by using the general framework of the Markov decision process (MDP) View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Local SNR considerations in decentralized CFAR detection

    Publication Year: 1998 , Page(s): 13 - 22
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (800 KB)  

    We consider the decentralized detection problem, involving N sensors and a central processor, in which the sensors transmit unquantized data to the fusion center. Assuming a homogeneous background for constant false-alarm rate (CFAR) analysis, we obtain the performances of the system for the Swerling I and Swerling III target models. We demonstrate that a simple nonparametric fusion rule at the central processor is sufficient for nearly optimum performance. The effect of the local signal-to-noise ratios (SNRs) on the performances of the optimum detector and two suboptimum detectors is also examined. Finally, we obtain a set of conditions, related to the SNRs, under which better performance may be obtained by using decentralized detection as compared with centralized detection View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A hardware-efficient, multirate, digital channelized receiver architecture

    Publication Year: 1998 , Page(s): 137 - 152
    Cited by:  Papers (35)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1204 KB)  

    An approach is presented to realizing a digital channelized receiver for signal intercept applications that provides a hardware efficient implementation of a uniform filter bank in which the number of filters K is greater than the decimation factor M. The proposed architecture allows simple channel arbitration logic to be used and provides reliable instantaneous frequency measurements, even in adjacent channel crossover regions. In the proposed implementation of the filter bank, K is related to M by K=FM where F is an integer. It is shown that the optimum selection of F allows the instantaneous frequency measurement to be made in the channel crossover region and the arbitration function to be based solely on the instantaneous frequency measurement. The development of a filter bank structure which combines the flexibility of the short-time Fourier transform (STFT) with the implementation efficiency of the polyphase filter bank decomposition, meeting these requirements and leading to a hardware-efficient implementation, is presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Evaluation of image-type glide slope performance in the presence of snow cover

    Publication Year: 1998 , Page(s): 71 - 83
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1100 KB)  

    A formulation for the effects that the ground-reflected signal has on the far-field performance of image-type glide slope is developed using geometrical optics. The effects of snow cover are then related to the formulation and analyzed. Results indicate that it is possible for certain types of dry snow to cause glide slope system performance to exceed U.S. Flight Inspection Manual (USFIM) tolerances at depths below existing Federal Aviation Administration (FAA) plowing criteria View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A PDF multisensor multitarget tracker

    Publication Year: 1998 , Page(s): 153 - 168
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1564 KB)  

    A previously presented probability density function (pdf) multitarget tracker is extended to a more complex and difficult problem. The input data is bearing measurements from multiple sensors over time, which includes clutter (false alarms) and true measurements (from detected targets) with errors. Targets may be missed. The output is the real-time determination of the number of targets present and their geographic x,y location. The implementation is the recursive numerical computation of the discrete pdf of each target and is derived from the conceptual joint pdf of all targets View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analytical solution of discrete colored noise ECA tracking filter

    Publication Year: 1998 , Page(s): 93 - 102
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    New analytical solutions of steady-state Kalman gains are presented for a discrete-time tracking filter with correlation in both the measurement noise and the target maneuver. The measurement noise model is a first-order discrete Markov process characterized by a correlation coefficient ρ. The target motion is examined for an exponentially correlated acceleration maneuver type in which the vehicle oscillation such as wind-induced-bending is also considered. The present solution method is based on factorizing the observed spectral density matrix Ψ(z) in frequency domain. The algorithm proposed here gives the Kalman gain matrix directly. For a case when the steady-state error covariance matrix is desired, such gains can be incorporated with the algebraic Riccati equation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An efficient algorithm for multisensor track fusion

    Publication Year: 1998 , Page(s): 200 - 210
    Cited by:  Papers (22)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB)  

    An efficient algorithm for track-to-track fusion by incorporating cross-covariance between tracks created by dissimilar sensors is described. An analytical solution of this problem is complicated if cross-correlation between sensors tracking the same target is taken into account. An explicit solution of the cross-covariance matrix at steady state is derived in terms of an integral. It is shown that solution of this integral involves inversion of a matrix whose elements are functions of parameters of individual trackers. Structure of this matrix is analyzed. An efficient analytical solution for inversion of this matrix is obtained. For fusion of similar sensors, it is shown that this matrix is reduced to the Routh-Hurwitz matrix which arises in the study of steady state stability of linear systems. Numerical results showing the amount of reduction of fused track covariance by taking into account the effects of cross-correlation between candidate tracks for fusion is also presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Impact of antenna-polarization response on direction-of-arrival measurement

    Publication Year: 1998 , Page(s): 319 - 329
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1016 KB)  

    The impact of emitter polarization on the distribution of phase and amplitude across an array of receiving apertures is analytically examined. That distribution is also dependent upon direction of arrival, and that dependence is the basis in receiving systems for direction finding (DF) and for beamforming with array antennas. Dependence on polarization may tend to confound DF measurement in a certain class of DF systems and may degrade array sidelobe performance in the presence of emitters of arbitrary polarization. Polarization becomes an issue when the array elements are not sufficiently uniform in their response to incident-field polarization. The effect of polarization on DF error from a phase-comparison monopulse receiver is quantified here View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Error analysis of analytic coarse alignment methods

    Publication Year: 1998 , Page(s): 334 - 337
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    Two analytic coarse alignment methods and the associated error analyses are provided for strapdown inertial navigation systems. Although both methods are derived from the same measurements of the local gravity vector and Earth rate, their error formulations are not completely identical. By properly selecting the basis to compute a best estimate of transformation matrix, the drift misalignment angles of analytic alignment can be made to be equivalent to those which can be found by physical gyrocompassing View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of Faraday rotation on polarimetric SAR

    Publication Year: 1998 , Page(s): 301 - 307
    Cited by:  Papers (11)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB)  

    The effect of ionospheric Faraday rotation on polarimetric synthetic aperture radar (SAR) imagery is evaluated theoretically. Faraday rotation is readily included in the polarimetric SAR system equation describing the received signal if the rotation angle is assumed constant over the synthetic aperture length. Deviations from a constant rotation angle over this length impact the validity of the derived system equation, but an explicit evaluation shows such effects to be negligible for most expected ionospheric conditions. The modified system equation provides a basis for calibration techniques that can be used to either remove or measure Faraday rotation effects in SAR imagery View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Processing throughput estimation for radar intercept receivers

    Publication Year: 1998 , Page(s): 84 - 92
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (796 KB)  

    Analytical expressions for the computational requirements of broad classes of radar pulse deinterleaving algorithms are developed. The analysis applies to block collection systems and is principally intended for systems with insufficient monopulse resolution to uniquely sort emitters on monopulse parameters alone. The analysis begins with triplet sequence search approaches and is confirmed by simulation. It is also shown that this approach generalizes to more complex deinterleaving schemes, including M-tuple search and time of arrival (TOA) difference histogramming. All cases exhibit the same basic functional form of quadratic dependence on the number of emitters, linear dependence on the collection time, and complex dependence on the pulse deletion (or dropping) probability View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Biased PNG law for impact with angular constraint

    Publication Year: 1998 , Page(s): 277 - 288
    Cited by:  Papers (48)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1000 KB)  

    A new homing guidance law is proposed to impact a target with a desired attitude angle. It is a variation of the conventional proportional navigation guidance (PNG) law which includes a supplementary time-varying bias. The proposed guidance law does not require a time-to-go estimation and has a simpler form. Analytic conditions for fulfilling the guidance goal are also provided. Simulation results demonstrate that the proposed guidance law has wider launch envelopes than the previous one and shows a good performance even against a maneuvering target View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effectiveness calculations in captive-carry HIL missile simulator experiments

    Publication Year: 1998 , Page(s): 124 - 136
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1904 KB)  

    Electronic countermeasures (ECMs) are instrumental in altering the flight path of an incoming active threat missile. To determine the effectiveness of the ECM, hardware-in-the-loop (HIL) threat missile simulators are tested in several types of experimental configurations (e.g., closed-loop in an anechoic chamber, open-loop captive-carry held tests on board an aircraft). A new class of modeling and simulation algorithms is presented that allows an accurate miss distance to be calculated from a high-bandwidth ECM captive-carry test result. The techniques combine the results from each test configuration and represent an improvement in evaluating an ECM effectiveness over a singly independent analysis. Anechoic chamber and captive-carry test results from an HIL antiship missile (ASM) simulator are used to demonstrate the algorithms and detail the feasibility of the approach View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Efficient approaches to low-cost high-fault coverage VLSI BIST designs

    Publication Year: 1998 , Page(s): 63 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (800 KB)  

    This work introduces a built-in self-test (BIST) design methodology that can sequentially test large very large scale integrated (VLSI) circuits with very high fault coverage. The proposed techniques, circular BIST ((BIST) and (BIST with pseudopartial scan (PPSCAN), are modeled after the principles of the circular self-test path (CSTP). The basis of this method is to trade a minimal increase in hardware overhead for a large increase in fault coverage. It is shown that this technique yields a much higher fault coverage with reasonable time and test vector length when compared with existing sequential test methods. The effectiveness of the technique has been demonstrated by applying it to practical VLSI circuits, which include: 1) the system control coprocessor (CP0) of MIPS 3000 central processing unit (CPU) core and 2) the SIMD graphic engine, namely, enhanced memory chip (EMC). The BIST results show that (BIST and its derivative (BIST with pseudopartial scan (PPSCAN) are feasible for practical VLSI designs and generate BIST with high fault coverage and low overhead View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Out of necessity: systems use of components required a complete new series of coaxial RF connectors

    Publication Year: 1998 , Page(s): 344 - 349
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1216 KB)  

    Omni Spectra, Inc. established the SMA lZF coaxial connector series in addition to other microwave components. The founders of the company saw that the time had come for a microwave components house to get into connector engineering with performance in mind. It was also time for a components house to establish quantity manufacturing. Along the way, some unusual things were done to promote wide-scale availability and use View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Periodic ambiguity functions of EQC-based TFHC

    Publication Year: 1998 , Page(s): 194 - 199
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    The time-frequency hop codes based upon extended quadratic congruences (TFHC-EQC) were developed previously (1988, 1991). The known results about the ambiguity functions of the TFHC-EQC are extended from aperiodic cases to periodic cases. Precisely, the following new results are proved: (1) The tight upper bound for the periodic auto-ambiguity function of the TFHC-EQC is 6; (2) the periodic cross-ambiguity upper bound of the TFHC-EQC is at least (N-1)/2; (3) there exists a subset TFHC-EQC of volume (N-1)/2 such that its periodic cross-ambiguity is tightly upper bounded by 8 View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Interacting multiple model methods in target tracking: a survey

    Publication Year: 1998 , Page(s): 103 - 123
    Cited by:  Papers (193)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2356 KB)  

    The Interacting Multiple Model (IMM) estimator is a suboptimal hybrid filter that has been shown to be one of the most cost-effective hybrid state estimation schemes. The main feature of this algorithm is its ability to estimate the state of a dynamic system with several behavior modes which can “switch” from one to another. In particular, the IMM estimator can be a self-adjusting variable-bandwidth filter, which makes it natural for tracking maneuvering targets. The importance of this approach is that it is the best compromise available currently-between complexity and performance: its computational requirements are nearly linear in the size of the problem (number of models) while its performance is almost the same as that of an algorithm with quadratic complexity. The objective of this work is to survey and put in perspective the existing IMM methods for target tracking problems. Special attention is given to the assumptions underlying each algorithm and its applicability to various situations View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Unified approach to developing single-stage power converters

    Publication Year: 1998 , Page(s): 211 - 223
    Cited by:  Papers (50)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1012 KB)  

    A unified approach to developing single-stage power converters which can fulfil multiple functions is presented. Four synchronous switches corresponding to the four common node types of two active switches are introduced. The approach is then to replace the active switches in multistage converters (in cascade or cascode connection) with one or several of the synchronous switches and their degenerated versions to form a single-stage converter. Illustrations of using these switches to develop single-stage converters are presented. These are started with the development of the well-known single-stage switch-mode converters (SMCs), buck-boost, Cuk, sepic, and Zeta (also named dual sepic), from the basic converters, buck and boost. Then, synthesis and applications of other single-stage converters are addressed. Due to increased component stresses, the developed single-stage converters are primarily suitable for applications with moderate power levels View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A sampling-based approach to wideband interference cancellation

    Publication Year: 1998 , Page(s): 2 - 12
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1044 KB)  

    Classical adaptive array schemes which use only complex spatial weights are inherently narrowband and consequently perform poorly when attempting to suppress wideband interference. The common solution to this problem is the use of tapped delay line filters in each spatial channel to facilitate space-time adaptive processing (STAP). The higher performance provided by the STAP architecture comes at the cost of a considerable increase in complexity. This paper presents a simpler technique based on programmable time adjustable sampling (TAS) that provides a limited number of wideband degrees of freedom. Two TAS methods are introduced: TAS-sidelobe canceler (TAS-SLC) is based on the sidelobe canceler, while TAS-minimum variance beamformer (TAS-MVB) is derived from the minimum variance beamformer. TAS is implemented by adjusting the sampling instant at selected array channels. TAS-SLC consists of controlling the sampling in the main channel of the sidelobe canceler With TAS-MVB array complex weights are substituted with TAS time delays. The performance of TAS methods with wideband interference is compared to the conventional sidelobe canceler and minimum variance beamformers. It is shown that TAS-SLC provides better performance than the sidelobe canceler, while TAS-MVB outperforms the minimum variance beamformer View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect in range difference position estimation due to stations' position errors

    Publication Year: 1998 , Page(s): 329 - 334
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB)  

    This work addresses the subject of systematic errors caused by using incorrect coordinates for the sites where the stations are located in a three-dimensional aircraft position estimation system, composed of one transmitter/receiver and three receiving stations. The differences in the aircraft ranges from the receiving stations are used to derive the position estimate. A general analytic expression is developed to assess the error resulting from using erroneous coordinates for the receivers location. Evaluation has been performed for certain representative conditions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Capacities of mobile air/ground radio communication systems employing cylindrical cells

    Publication Year: 1998 , Page(s): 247 - 256
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (956 KB)  

    Cylindrical cells represent actual service volumes used in terminal areas (airports) for air traffic control (ATC) communications between pilots and ground controllers. The channel capacities of simplex and duplex frequency division multiplexing (FDM) mobile air/ground (A/G) radio communication systems employing cylindrical cells are compared assuming a network of identical cylindrical cells and a dedicated radio channel per group of aircraft and its ground controller. The two systems are compared considering both cochannel and adjacent channel interferences for analog and digital modulation. Then, capacities of duplex FDM and code division multiplexing (CDM) are compared under the same assumptions for digital modulation. The capacity of FDM depends mainly on the frequency reuse distance while the capacity of CDM is limited by the self users interference. This work shows that the capacity ratio of duplex and simplex FDM systems depends on the cell dimensions. It also shows that considering ATC requirements, FDM provides a higher capacity than CDM for all the cell dimension ranges considered 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