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Aerospace and Electronic Systems, IEEE Transactions on

Issue 4 • Date Oct 1993

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Displaying Results 1 - 25 of 33
  • Carrier-wave interference to Loran-C: a statistical evaluation

    Publication Year: 1993 , Page(s): 1260 - 1274
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (980 KB)  

    Loran-C is a pulsed, hyperbolic radio aid for long-range marine, air, and land navigation. The worldwide expansion of Loran-C, especially in Europe, has focused attention on carrier-wave interference to the system. The effects of a multiplicity of carrier-wave interferers (CWIs) on receiver timing measurement accuracy are considered. Both the phase tracking and the cycle-selection performance of receivers are quantified in terms of the probabilities that they will operate correctly within the arbitrarily set error limits. Characteristic functions (CFs) are used to compute these probabilities. Analyses and results are presented for typical situations. The relative sensitivity of the phase tracking and cycle-selection functions to interfering signals are discussed View full abstract»

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  • Experimental study in adaptive tracking control

    Publication Year: 1993 , Page(s): 1204 - 1215
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB)  

    The authors describe an experimental study of adaptive pointing and tracking control for flexible spacecraft conducted on a complex ground experiment facility. The algorithm used is based on a multivariable direct model reference adaptive control law. Several experimental validation studies performed using this algorithm for vibration damping and robust regulation are extended by addressing the pointing and tracking problem. As is consistent with an adaptive control framework, the plant is assumed to be poorly known to the extent that only system level knowledge of its dynamics is available. Explicit bounds on the steady-state pointing error are derived as functions of the adaptive controller design parameters. It is shown that good tracking performance can be achieved in an experimental setting by adjusting adaptive controller design weightings according to the guidelines indicated by the analytical expressions for the error View full abstract»

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  • Joint probabilistic data association for autonomous navigation

    Publication Year: 1993 , Page(s): 1275 - 1286
    Cited by:  Papers (16)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (812 KB)  

    A new autonomous navigation scheme based on the joint probabilistic data association (JPDA) approach that processes landmark detections in the field of view (FOV) of an on-board sensor is developed. These detections-some true, some false-are associated to a set of stored landmarks and used to update the state of the vehicle. The results obtained from Monte Carlo simulations prove the ability of this navigation filter to perform in very high false alarm environments. In the different environmental conditions tested in the simulations, the performance of the JPDA navigation filter (JPDANF) is very close to that of the filter based on perfect data association. The very efficient cluster decomposition algorithm presented for the purpose of the navigation problem can also be used in many multitarget tracking applications View full abstract»

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  • Solution and performance analysis of geolocation by TDOA

    Publication Year: 1993 , Page(s): 1311 - 1322
    Cited by:  Papers (61)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (796 KB)  

    One method of geolocation is based on measuring the time difference of arrivals (TDOAs) of a signal received by three or four geostationary satellites. The received signals are cross-correlated to determine the TDOAs and a set of nonlinear equations are solved to produce the location estimate. An exact solution for the transmitter position is derived for the three or four receiver cases. Extension of the solution method to more receivers is straightforward. An analysis of the performance of the system is given, together with expressions for predicting the localization mean-square errors (MSEs) and bias, and the Cramer-Rao bound. Both precision in TDOA measurements and the relative geometry between receivers and transmitter affect the localization accuracy. The geometric factors act as multipliers to the TDOA variance in the bias and MSE formulae. A study of the dependency of the geometric factors on transmitter position and satellite spacings are provided, as well as simulation results View full abstract»

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  • Digital baseband processor for the GPS receiver (parts I and II)

    Publication Year: 1993 , Page(s): 1343 - 1349
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    A global positioning system (GPS) receiver has been modeled mathematically and implemented in software. The digital baseband processor of the receiver performs the maximum likelihood estimations (MLEs) of the GPS observables. The following issues are discussed: the fundamentals of the digital GPS receiver, the modeling of the digital baseband processor, and the performance of the modeled static and dynamic receivers. The software-based receiver is more flexible, less expensive, and more accurate compared to hardware receivers in receiver designs and GPS system performance analysis View full abstract»

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  • Performance analysis for DOA estimation algorithms: unification, simplification, and observations

    Publication Year: 1993 , Page(s): 1170 - 1184
    Cited by:  Papers (84)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    Subspace based direction-of-arrival (DOA) estimation has motivated many performance studies, but limitations such as the assumption of an infinite amount of data and analysis of individual algorithms generally exist in these performance studies. The authors have previously proposed a unified performance analysis based on a finite amount of data and achieved a tractable expression for the mean-squared DOA estimation error for the multiple signal classification (MUSIC). Min-Norm, estimation of signal parameters using rotational invariance techniques (ESPRIT), and state-space realization algorithms. However, this expression uses the singular values and vectors of a data matrix, which are obtained by the highly nonlinear transformation of the singular value decomposition (SVD). Thus the effects of the original data parameters such as numbers of sensors and snapshots, source coherence and separations were not explicitly analyzed. The authors unify and simplify this previous result and derive a unified expression based on the original data parameters. They analytically observe the effects of these parameters on the estimation error View full abstract»

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  • Image texture synthesis-by-analysis using moving-average models

    Publication Year: 1993 , Page(s): 1110 - 1122
    Cited by:  Papers (16)  |  Patents (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1312 KB)  

    A synthesis-by-analysis model for texture replication or simulation is presented. This model can closely replicate a given textured image or produce another image that although distinct from the original, has the same general visual characteristics and the same first and second-order gray-level statistics as the original image. The texture synthesis algorithm, proposed contains three distinct components: a moving-average (MA) filter, a filter excitation function, and a gray-level histogram. The analysis portion of the texture synthesis algorithm derives the three from a given image. The synthesis portion convolves the MA filter kernel with the excitation function, adds noise, and modifies the histogram of the result. The advantages of this texture model over others include conceptually and computationally simple and robust parameter estimation, inherent stability, parsimony in the number of parameters, and synthesis through convolution. The authors describe a procedure for deriving the correct MA kernel using a signal enhancement algorithm, demonstrate the effectiveness of the model by using it to mimic several diverse textured images, discuss its applicability to the problem of infrared background simulation, and include detailed algorithms for the implementation of the model View full abstract»

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  • Improved DC/AC interface inverter for high-frequency space applications

    Publication Year: 1993 , Page(s): 1150 - 1163
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (868 KB)  

    A DC/AC interface inverter for a high-frequency space power distribution system that uses dual asymmetrical resonant bridges is examined. Compared to the conventional approach in which two symmetrical bridges are used, the asymmetrical bridges arrangement offers better use of the installed kVA rating and efficiency of the inverter system. A simplified approach for modeling the inverter system in steady-state is presented, and a criteria to select the resonant components is given. A detailed simulation is performed for the following: a symmetrical inverter system with a resistive load, an asymmetrical inverter system with a resistive load, and an asymmetrical inverter system with the type-1A AC/DC converter load View full abstract»

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  • Processor equivalence for daisy chain load sharing processors

    Publication Year: 1993 , Page(s): 1216 - 1221
    Cited by:  Papers (23)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    A linear daisy chain of processors in which processor load is divisible and shared among the processors is examined. It is shown that two or more processors can be collapsed into a single equivalent processor. This equivalence allows a characterization of the nature of the minimal time solution, a simple method to determine when to distribute load for linear daisy chain networks of processors without front end communication subprocessors and closed form expressions for the equivalent processing speed of infinitely large daisy chains of processors View full abstract»

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  • Robust Kalman filter design for predictive wind shear detection

    Publication Year: 1993 , Page(s): 1185 - 1194
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    Severe low-altitude wind shear is a threat to aviation safety. Newly developed airborne sensors measure the radial component of wind along a line directly in front of an aircraft. The authors use optimal estimation theory to define a detection algorithm to warn of hazardous wind shear from these sensors. To achieve robustness, a wind shear detection algorithm must distinguish threatening wind shear from less hazardous gustiness, despite variations in wind shear structure. Statistical analysis methods to refine wind shear detection algorithm robustness are presented. Computational methods predict the ability to warn of severe wind shear and avoid false warning. Comparative capability of the detection algorithm as a function of its design parameters is determined, identifying designs that provide robust detection of severe wind shear View full abstract»

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  • Optimal multiple level decision fusion with distributed sensors

    Publication Year: 1993 , Page(s): 1252 - 1259
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    A data fusion model consisting of several levels of parallel decision fusions is considered. Global optimization of such a model is discussed to obtain the fusion rules for overall optimal performance. The reliability analysis of the proposed model is carried out to establish its superiority over the existing parallel and serial fusion models View full abstract»

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  • An alternate algorithm for discrete-time filtering

    Publication Year: 1993 , Page(s): 1123 - 1136
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1100 KB)  

    The discrete-time Kalman filter is an optimal estimator for the states of a linear, stochastic system. It assumes that measurements are linear combinations of the states, and all disturbances are Gaussian. The influence diagram, a decision analysis tool that provides an algorithm for discrete-time filtering equivalent to the Kalman filter when the influence diagram represents Gaussian random variables, is discussed. The influence diagram algorithm is a factored form of the Kalman filter, similar to other factored forms such as the U-D filter. Compared with the Kalman filter, it offers improved numerical properties. Compared with other factored forms, it offers a reduced computational load View full abstract»

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  • Multitarget detection using Kalman-based average displacement estimator

    Publication Year: 1993 , Page(s): 1195 - 1203
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1068 KB)  

    The anomaly in the displacement estimates obtained from a low-level Kalman-based average displacement estimator is used to detect multiple targets in a forward-looking infrared (FLIR) scene. The displacement estimates originating from the targets could be associated with the detected multiple targets and an updated estimated position of the target could be obtained. This procedure could be repeated for all targets in the scene to obtain multitarget tracking. The behavior of the expected value of the displacement estimates as a function of the number of iterations is investigated. The behavior of the displacement error covariance matrix and the Kalman gain matrix are discussed as functions of the number of iterations View full abstract»

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  • Processing requirements for multisensor low-cost brilliant munitions

    Publication Year: 1993 , Page(s): 1084 - 1094
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (936 KB)  

    A generic mission for an autonomous brilliant munition is presented and used to identify the functions that embedded signal processors must perform. Based on these functions and other operational factors such as weather, countermeasures, larger search areas, reduced false alarm rates, and increased munition maneuverability, the processing loads in bits/second messages/second, operations/second, and instructions/second are derived. An evaluation of general implementation issues such as the requirements for data fusion, distributed and parallel processing architectures, reliable software, and low-cost hardware is presented View full abstract»

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  • Spread-spectrum code and carrier synchronization errors caused by multipath and interference

    Publication Year: 1993 , Page(s): 1359 - 1365
    Cited by:  Papers (43)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    The influence of multipath propagation and spread-spectrum interference on code and carrier synchronization is investigated. Both coherent and noncoherent delay lock loops (DLLs) are considered, with arbitrary early-late spacings up to one chip time. The coherent DLL is shown to have a major advantage; for a relatively high fading bandwidth, it has negligible tracking errors, while a noncoherent DLL always has a certain bias error. The results are particularly interesting for spread-spectrum positioning systems like Global Positioning System (GPS) and GLONASS View full abstract»

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  • Further results on LMSS experiment in Kyoto City

    Publication Year: 1993 , Page(s): 1237 - 1243
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    In February of 1990, land mobile satellite experiments were conducted in Kyoto City, Japan, using the Engineering Test Satellite V (ETS-V). The received signal strength was recorded, as was the speed of the mobile as it traversed various downtown streets. The setting was that of a built-up urban area with medium and high rise buildings, electric utility poles, and trees lining the streets. These caused obstruction to the satellite line of sight (LOS). The signal level fluctuation due to diffraction of radio waves by the urban structures is analyzed. The results obtained from the measurements and theoretical calculation agree. The spatial frequencies due to diffraction are found to vary between 1.8 Hz to 5.3 Hz. It is concluded that this variation of received signal level will not adversely affect the receiver performance. Based on recorded signal strength, the performance of a digital land mobile satellite system (LMSS), under the above mentioned environment, is analyzed and the results presented View full abstract»

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  • Strategic route planning and sensor fusion

    Publication Year: 1993 , Page(s): 1357 - 1359
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB)  

    A method of looking at sensor fusion that combines sensor outputs in a simple way to derive an upper bound of the detection probability is presented. The concept is useful in strategic route planning and for assessing tradeoffs between various possible sensor upgrades. It can be used to guide expenditures so that funds applied are applied in a well-balanced manner. A toy problem is analyzed to demonstrate the concept View full abstract»

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  • Optimum selection of error control coding using neural networks

    Publication Year: 1993 , Page(s): 1074 - 1083
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (824 KB)  

    Significant performance improvements may be obtained in digital communication systems if error control coding is properly applied. However, selection of a coding scheme for specific applications is often a complicated task. The choice is affected by a set of system design goals. Some of these goals impose case-dependent conflicting requirements. Similar scheme selection problems exist in many engineering system design processes. A knowledge-combined neural network approach is developed and applied to optimum coding selection. The proposed approach utilizes a neural network trained not only by precedent examples but also by knowledge rules to draw conclusions. It is shown that artificial neural networks (ANNs) can provide effective solutions to the problems encountered in building systems that emulate a coding specialist's expertise View full abstract»

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  • Large angle pitch attitude maneuver of a satellite using solar radiation pressure

    Publication Year: 1993 , Page(s): 1164 - 1169
    Cited by:  Papers (6)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    The force exerted by the solar radiation, though very small in magnitude, produces significant effects, especially in the case of high altitude satellites. The solar radiation pressure represents one freely available environmental force that may be put to use for various purposes. This may lead to enhancement of the life of the satellite since it consumes a very nominal amount of on-board energy. The advantages offered by the solar radiation pressure have drawn the attention of several researchers. Various controllers were proposed for many space missions, particularly for attitude control and stabilization of satellites. A controller for achieving large angle pitch attitude maneuver is described. The proposed control law is very simple in its form and requires a minimum number of on-board computations. Varieties of cases are tried and the effect of various parameters is studied View full abstract»

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  • Capacitive-loaded push-pull parallel-resonant converter

    Publication Year: 1993 , Page(s): 1287 - 1296
    Cited by:  Papers (11)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    Results of a theoretical and experimental investigation of a capacitive-loaded push-pull parallel-resonant DC-DC converter (CL-PPRC) are presented and discussed. The push-pull parallel-resonant converter (PPRC) is driven by a lower-than-resonance frequency and the secondary voltage is rectified and smoothed by a capacitive filter. The CL-PPRC is shown to operate in the zero voltage switching (ZVS) mode with a boost-like DC transfer ratio that is approximately linear with the period of the switching frequency. Experimental results of a 180 W, high output voltage (1.8 KV) prototype are found to be in good agreement with the analysis, models, and simulation results presented. The basic characteristic of ZVS, the fact that the resonant current is passing through the switches only during a fraction of the period, the high-voltage transfer ratio, and the inherent input/output (I/O) isolation, make the proposed topology a viable design alternative in avionic and aerospace applications View full abstract»

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  • The beginnings of stealth technology

    Publication Year: 1993 , Page(s): 1377 - 1385
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1056 KB)  

    The work led by the Air Force Avionics Laboratory from the early 1950s to 1970s is discussed. Emphasis is placed on radar echo, although all observables-infrared radiation, optical, acoustics, etc.-are important to stealth design. The current capability to minimize observables is traced from the first efforts to understand what determines radar echo through the development of materials and techniques to minimize it. Applications and demonstrations are reviewed View full abstract»

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  • Multiposition alignment of strapdown inertial navigation system

    Publication Year: 1993 , Page(s): 1323 - 1328
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    The authors demonstrate that the stationary alignment of strapdown inertial navigation system (SDINS) can be improved by employing the multiposition/technique. Using an observability analysis, it is shown that an optimal two-position alignment not only satisfies complete observability conditions but also minimizes alignment errors. This is done by analytic rank testing of the stripped observability matrix and numerical calculation of the error covariance. It is also shown that an optimal three-position alignment accelerates the convergence of the alignment error compared with two-position alignment View full abstract»

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  • Removal of alignment errors in an integrated system of two 3-D sensors

    Publication Year: 1993 , Page(s): 1333 - 1343
    Cited by:  Papers (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (788 KB)  

    An algorithm is presented to relatively align two 3-D sensors using targets that are tracked by both sensors. The algorithm estimates and removes sensor biases and sensor frame orientation errors. To illustrate this technique, the alignment algorithm is applied to simulated track data from two sensors View full abstract»

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  • Effects of output filter on cross regulation in SRC

    Publication Year: 1993 , Page(s): 1095 - 1109
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (880 KB)  

    Cross regulation performance of multioutput series resonant converter (SRC) topologies using capacitive or inductive filters is analyzed. The steady state cross regulation characteristics are derived using the state-plane techniques and are illustrated by the examples of two-output SRCs with capacitive and inductive filters. The characteristic curves show that over some range of output currents, the cross regulation performance of an SRC with an inductive filter is much improved over the SRC with capacitance filter and less dependent on the tolerances in leakage inductances and the loading on unregulated outputs. It is shown that the converter control characteristics of an SRC with an inductive filter are relatively unaffected by the addition of the second output. The theoretical results are verified by simulation View full abstract»

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  • Multiresolutional filtering using wavelet transform

    Publication Year: 1993 , Page(s): 1244 - 1251
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    An algorithm for optimal and dynamic multiresolutional distributed filtering is derived. The wavelet transform is utilized as a bridge linking signals at different resolution levels. The algorithm can be employed for dynamic multisensor/data fusion 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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Editor-in-Chief
Lance Kaplan
Army Research Laboratory