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Articles 32641 - 32670 of 36793

Full-Text Articles in Engineering

Radiation From An Impedance Loaded Parallel-Plate Waveguide, Fi̇li̇z Bi̇rbi̇r, Ali̇nur Büyükaksoy Jan 2000

Radiation From An Impedance Loaded Parallel-Plate Waveguide, Fi̇li̇z Bi̇rbi̇r, Ali̇nur Büyükaksoy

Turkish Journal of Electrical Engineering and Computer Sciences

A hybrid method consisting of employing the mode matching method in conjunction with the Fourier transform technique is used to analyze the radiation of the dominant TEM-wave from an impedance loaded parallel-plate waveguide. The hybrid method that we adopt here reduces the related boundary value problem to a scalar modified Wiener-Hopf equation of the second kind. The solution involves infinitely many unknown constants satisfying an infinite system of linear algebraic equations susceptible to a numerical treatment. Some computational results illustrating the effects of various parameters on the radiation phenomenon are also presented.

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A Pseudo Spot Price Algorithm Applied To The Pumped-Storage Hydraulic Unit Scheduling Problem, Sali̇h Fadil, Celal Yaşar Jan 2000

A Pseudo Spot Price Algorithm Applied To The Pumped-Storage Hydraulic Unit Scheduling Problem, Sali̇h Fadil, Celal Yaşar

Turkish Journal of Electrical Engineering and Computer Sciences

A lossy electric power system that contains thermal units and a pumped-storage hydraulic unit is considered in this paper. The total cost of thermal units in an operation cycle is minimized under some possible electric and hydraulic constraints of the units. The operation cycle is divided into time intervals where the system loads are assumed to remain constant. The proposed solution technique has two main parts. In the first part, the active thermal generations and active generation or pumping power of the pumped-storage unit in all time intervals are determined by using units' active generation incremental costs and pseudo spot …

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A Fuzzy Identification Method For Nonlinear Systems, İbrahi̇m Eksi̇n, Osman Kaan Erol Jan 2000

A Fuzzy Identification Method For Nonlinear Systems, İbrahi̇m Eksi̇n, Osman Kaan Erol

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, two mathematical ways of building a fuzzy model of both linear and nonlinear systems are presented and compared. In order to determine a model for a nonlinear system, the phase plane is divided into sub-regions and a linear model is assigned for each of these regions. This linear model is represented either in state-space or ARX model form. To determine the pre-selected parameters of the linear system model under study, least-square identification method is used. Then these linear models are arranged in a fuzzy manner to characterize the overall system behavior. The results show that this method …

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A Schooling On Their Implications For Software Engineering [Trends], Ann K. Miller Jan 2000

A Schooling On Their Implications For Software Engineering [Trends], Ann K. Miller

Electrical and Computer Engineering Faculty Research & Creative Works

A discussion is presented on trends in software engineering. This can be done by simply extrapolating some of the popular, current trends. And, in fact, we examine a few of these obvious indicators. However, software engineering has had new approaches that are more revolutionary than evolutionary. In particular, we try to discern trends in software engineering based on trends in delivered software systems.

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The 2-Way Thrashing-Avoidance Cache (Tac): An Efficient Instruction Cache Scheme For Object-Oriented Languages, Yul Chu, M. R. Ito Jan 2000

The 2-Way Thrashing-Avoidance Cache (Tac): An Efficient Instruction Cache Scheme For Object-Oriented Languages, Yul Chu, M. R. Ito

Electrical and Computer Engineering Faculty Publications

This paper presents a new instruction cache scheme: the TAC (Thrashing-Avoidance Cache). A 2-way TAC scheme employs 2-way banks and XOR mapping functions. The main function of the TAC is to place a group of instructions separated by a call instruction into a bank according to the Bank Selection Logic (BSL) and Bank-originated Pseudo-LRU replacement policies (BoPLRU). After the BSL initially selects a bank on an instruction cache miss, the BoPLRU will determine the final bank for updating a cache line as a correction mechanism. These two mechanisms can guarantee that recent groups of instructions exist in each bank safely. …

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A Hysteresis Current-Regulated Control For Multi-Level Drives, Keith Corzine Jan 2000

A Hysteresis Current-Regulated Control For Multi-Level Drives, Keith Corzine

Electrical and Computer Engineering Faculty Research & Creative Works

Most multi-level converters are controlled through the use of voltage-source based control techniques such as space-vector modulation or multi-level sine-triangle modulation. However, in many applications such as field oriented drives, a high bandwidth current-source inverter based control is more desirable. In this paper, the concept of a multi-level hysteresis current-source control is set forth. The new control is experimentally verified using a four-level converter/induction motor drive system and the results are compared to a space vector modulation controller. A dynamic study involving a step change in current command demonstrates the controls high bandwidth.

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A Robust Proportionate Affine Projection Algorithm For Network Echo Cancellation, T. Gansler, J. Benesty, Steven L. Grant, M. M. Sondhi Jan 2000

A Robust Proportionate Affine Projection Algorithm For Network Echo Cancellation, T. Gansler, J. Benesty, Steven L. Grant, M. M. Sondhi

Electrical and Computer Engineering Faculty Research & Creative Works

Echo cancelers which cover longer impulse responses (greater than or equal to 64 ms) are desirable. Long responses create a need for more rapidly converging algorithms in order to meet the specifications for network echo cancelers devised by the ITU (International Telecommunication Union). In general, faster convergence implies a higher sensitivity to near-end disturbances, especially "double-talk." Previously, a fast converging algorithm called the proportionate NLMS (normalized least mean squares) algorithm (PNLMS) has been proposed. This algorithm exploits the sparseness of the echo path in order to increase the convergence rate. A robust version of PNLMS has also been presented which …

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Advances Of Gyromagnetic Electronics For Emc Problems, Marina Koledintseva, L. K. Mikhailovsky, Alexander A. Kitaytsev Jan 2000

Advances Of Gyromagnetic Electronics For Emc Problems, Marina Koledintseva, L. K. Mikhailovsky, Alexander A. Kitaytsev

Electrical and Computer Engineering Faculty Research & Creative Works

A number of EMC problems at microwaves-detection and measurement of power (spectrum) of the signals and suppression of unwanted radiation-can be solved owing to the results obtained in the field of gyromagnetic (spin) electronics. The latter deals with the unique properties of gyromagnetic media (GM) based on microwave ferrites, including high-anisotropy hexagonal ferrites that do not need an intense magnetization field for their operation at ferromagnetic resonance. Approaches to the study of the interaction of GM with an electromagnetic field and ways of modeling frequency-selective measuring devices, absorbing coatings and all-mode filters of harmonics on the basis of GM are …

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Fourier Based Three Phase Power Metering System, Scott C. Smith, M. J. Devaney Jan 2000

Fourier Based Three Phase Power Metering System, Scott C. Smith, M. J. Devaney

Electrical and Computer Engineering Faculty Research & Creative Works

The increased application of higher frequency nonlinear loads, such as electronic fluorescent ballasts and higher speed adjustable drives, has resulted in the need to monitor the higher power system harmonics which were largely ignored in earlier power monitors. Addressing this need requires a meter with substantially higher sample rate and greater computational power. This paper describes a zero-blind, three-phase, three-element power meter that samples three voltages and four currents at 256 points per cycle. The instrument relies on the FFT to compute real and reactive power at each harmonic and reports total real, reactive, and distortion power on each phase. …

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Comparison Of A Heuristic Dynamic Programming And A Dual Heuristic Programming Based Adaptive Critics Neurocontroller For A Turbogenerator, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley Jan 2000

Comparison Of A Heuristic Dynamic Programming And A Dual Heuristic Programming Based Adaptive Critics Neurocontroller For A Turbogenerator, Ganesh K. Venayagamoorthy, Donald C. Wunsch, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents the design of a neurocontroller for a turbogenerator that augments/replaces the conventional automatic voltage regulator and the turbine governor. The neurocontroller uses a novel technique based on the adaptive critic designs with emphasis on heuristic dynamic programming (HDP) and dual heuristic programming (DHP). Results are presented to show that the DHP based neurocontroller is robust and performs better than the HDP based neurocontroller, as well as the conventional controller, especially when the system conditions and configuration changes.

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Comparison Of Text-Dependent Speaker Identification Methods For Short Distance Telephone Lines Using Artificial Neural Networks, Ganesh K. Venayagamoorthy, N. Sundepersadh Jan 2000

Comparison Of Text-Dependent Speaker Identification Methods For Short Distance Telephone Lines Using Artificial Neural Networks, Ganesh K. Venayagamoorthy, N. Sundepersadh

Electrical and Computer Engineering Faculty Research & Creative Works

The transition to democracy in South Africa has brought with it certain challenges. The main challenge is to get rid of crime and corruption. The paper presents a technique to combat white-collar crime in telephone transactions by identifying and verifying speakers using artificial neural networks (ANNs). Results are presented to show that speaker identification is feasible and this is illustrated with two different types of ANN architectures and with two different types of characteristic features as inputs to ANNs.

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Decentralized Online Neuro-Identification Of Turbogenerators In A Multi-Machine Power System, Ganesh K. Venayagamoorthy, Ronald G. Harley Jan 2000

Decentralized Online Neuro-Identification Of Turbogenerators In A Multi-Machine Power System, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a new and a novel technique based on Artificial Neural Networks (ANNs) for nonlinear model of turbogenerators in a multi-machine power system. Only local measurements are required by each ANN in this new method, and hence it is called decentralized neuro-identificiation. Each turbogenerator in the power system is quipped with an ANN which is able to identify (or model) its particular turbogenerator from moment to moment This information can then be used by a second ANN at each generator to enable effective control of the nonlinear non-stationary process under all operating conditions. Simulation results are presented in …

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Power Education At The Crossroads, Badrul H. Chowdhury Jan 2000

Power Education At The Crossroads, Badrul H. Chowdhury

Electrical and Computer Engineering Faculty Research & Creative Works

To meet the demands of designing and running far more complex and highly integrated electricity systems, a new kind of power engineer is needed. In this paper, the author describes how, though students tend to favor higher-tech and more lucrative fields than power Engineering; reports of the discipline''s demise are exaggerated

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Design And Evaluation Of A Specialized Computer Architecture For Manipulating Binary Decision Diagrams, Robert K. Hatt Jan 2000

Design And Evaluation Of A Specialized Computer Architecture For Manipulating Binary Decision Diagrams, Robert K. Hatt

Dissertations and Theses

Binary Decision Diagrams (BDDs) are an extremely important data structure used in many logic design, synthesis and verification applications. Symbolic problem representations make BDDs a feasible data structure for use on many problems that have discrete representations. Efficient implementations of BOD algorithms on general purpose computers has made manipulating large binary decision diagrams possible. Much research has gone into making BOD algorithms more efficient on general purpose computers. Despite amazing increases in performance and capacity of such computers over the last decade, they may not be the best way to solve large, specialized problems. A computer architecture designed specifically to …

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Integrated Floorplanning And Buffer Insertion For Bus-Based Microprocessor Designs, Faran Rafiq Jan 2000

Integrated Floorplanning And Buffer Insertion For Bus-Based Microprocessor Designs, Faran Rafiq

Dissertations and Theses

In this thesis, we propose a novel algorithm for the interconnect driven floorplanning problem that integrates bus planning with floorplanning. This integrated floorplanner is intended for bus-based designs in which the layout is considered to be a set of blocks connected through buses. Each bus consists of a large number of wires. Our floorplanner allocates the exact location and shape of the interconnect (both above and between the circuit blocks) and ensures routability as well as optimizes the timing goals. Our experiments with benchmarks clearly show the superiority of integrated floorplanning approach over the classical floorplan-analyze-and-then-refloorplan approach. Our initial results …

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Distance Spectra For Trellis Coded Modulation Schemes On Channels With Intersymbol Interference, Sabi̇re Haciömeroğlu, Melek D. Yücel Jan 2000

Distance Spectra For Trellis Coded Modulation Schemes On Channels With Intersymbol Interference, Sabi̇re Haciömeroğlu, Melek D. Yücel

Turkish Journal of Electrical Engineering and Computer Sciences

The effect of intersymbol interference on distance spectra for trellis coded 8-PSK, 16-QAM and 32-AMPM modulation schemes is evaluated using the methods proposed by Schlegel. Distance spectra of 16-state 8-PSK scheme are computed for different intersymbol interference channels. It is seen that on channels with intersymbol interference the spectral lines are spread into a nearly continuous spectrum and the minimum Euclidean distance between codewords decreases severely. Hence, although the main contribution at large signal to noise ratios comes from the minimum Euclidean distance ( d_{free} ) , higher spectral components also become very important at moderate values of the signal …

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Control Chart Pattern Recognition Using Artificial Neural Networks, Şeref Sağiroğlu, Erkan Beşdok, Mehmet Erler Jan 2000

Control Chart Pattern Recognition Using Artificial Neural Networks, Şeref Sağiroğlu, Erkan Beşdok, Mehmet Erler

Turkish Journal of Electrical Engineering and Computer Sciences

Precise and fast control chart pattern (CCP) recognition is important for monitoring process environments to achieve appropriate control and to produce high quality products. CCPs can exhibit six types of pattern: normal, cyclic, increasing trend, decreasing trend, upward shift and downward shift. Except for normal patterns, all other patterns indicate that the process being monitored is not functioning correctly and requires adjustment. This paper describes a new type of neural network for speeding up the training process and to compare three training algorithms in terms of speed, performance and parameter complexity for CCP recognition. The networks are multilayered perceptrons trained …

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New Buffer Layers, Large Band Gap Ternary Compounds: Cualte², K. Benchouk, E. Benseddik, C. O. El Moctar, J. C. Bernède, S. Marsillac, J. Pouzet, A Khellil Jan 2000

New Buffer Layers, Large Band Gap Ternary Compounds: Cualte², K. Benchouk, E. Benseddik, C. O. El Moctar, J. C. Bernède, S. Marsillac, J. Pouzet, A Khellil

Electrical & Computer Engineering Faculty Publications

After deposition, by evaporation under vacuum, of Al/Cu/Te, multilayer structures, annealing at 673 K or more for half an hour, under argon flow, allows CuAlTe2 films crystallized in the chalcopyrite structure to be obtained. The optical and electrical properties are interpreted by introducing the influence of impurity foreign phases present in the films. The optical properties are sensitive to the small Al2O3 domains randomly distributed into the CuAlTe2 polycrystalline matrix. The optical band gap is slightly increased (2.35 eV) by the presence of alumina. The conductivity measurements show that a short circuit effect can be induced by a binary Cu2-xTe …

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New Free-Space Multistage Optical Interconnection Network And Its Matrix Theory, Fengguang Luo, Mingcui Cao, Anjun Wan, Jun Xu, Xinjun Zhou, Cong Deng Jan 2000

New Free-Space Multistage Optical Interconnection Network And Its Matrix Theory, Fengguang Luo, Mingcui Cao, Anjun Wan, Jun Xu, Xinjun Zhou, Cong Deng

Electro-Optics and Photonics Faculty Publications

A new free-space multistage optical interconnection network which is called the Comega interconnection network is presented. It has the same topological construction for the cascade stages of the Comega interconnection. The concept of the left Comega and the right Comega interconnection networks are given to describe the whole Comega interconnection network. The matrix theory for the Comega interconnection network is presented. The route controlling of the Comega interconnection network is decided based on the matrix analysis. The node switching states in cascade stages of the 8 by 8 Comega interconnection network for the route selection are given. The data communications …

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Cellular Automata Study Of The Feasibility Of A Parallel Optical Computer, Jason Robert Lane Jan 2000

Cellular Automata Study Of The Feasibility Of A Parallel Optical Computer, Jason Robert Lane

Masters Theses

"The speed of modern electronic computers has inherent design limitations which will soon be reached. A possible substitute is the optical computer. In this project, the feasibility of the optical computer is explored by designing and building a parallel optical system. This system is used to test the basic principles that would govern a parallel optical computer. The system is based on the principle of cellular automata, which is a simulation technique used to study interactions of objects in a system. The following goals were set. The system would be based on cellular automata. A one-dimensional array with nine cells, …

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Investigation Of Pattern Classification And Feature Selection Of Gaussian Processes, Vivek Ramaprasad Jan 2000

Investigation Of Pattern Classification And Feature Selection Of Gaussian Processes, Vivek Ramaprasad

Masters Theses

"This thesis focuses on the application of statistical techniques for pattern classification where the patterns are power spectra of the recorded acoustic signals of occluded objects. Different approaches used to classify are : The Bayes linear and piece-wise linear classifiers, the correlation classifier, classification using error spectra and the clustering algorithm. Classifiers were designed and experiments were conducted to investigate the performance. The performance is evaluated in terms of the percentage efficiency by counting the number of vectors identified correctly and the number of vectors which were misclassified. The feature vectors from primitive measurement space is then reduced to lesser …

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Vhdl Design And Simulation For Embedded Zerotree Wavelet Quantisation, Hung Huynh Jan 2000

Vhdl Design And Simulation For Embedded Zerotree Wavelet Quantisation, Hung Huynh

Theses : Honours

This thesis discusses a highly effective still image compression algorithm – The Embedded Zerotree Wavelets coding technique, as it is called. This technique is simple but achieves a remarkable result. The image is wavelet-transformed, symbolically coded and successive quantised, therefore the compression and transmission/storage saving can be achieved by utilising the structure of zerotree. The algorithm was first proposed by Jerome M. Shapiro in 1993, however to minimise the memory usage and speeding up the EZW processor, a Depth First Search method is used to transverse across the image rather than Breadth First Search method as initially discussed in Shapiro's …

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Time Delayed Process Model Parameter Estimation: A Classification Of Techniques, Aidan O'Dwyer Jan 2000

Time Delayed Process Model Parameter Estimation: A Classification Of Techniques, Aidan O'Dwyer

Conference papers

An extensive though scattered literature exists on the estimation of the model parameters of time delayed processes. However, it is possible to identify themes that are common to many of the proposed techniques. The intention of this paper is to provide a framework against which the literature may be viewed.

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A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 1: Pi Controller Tuning Rules, Aidan O'Dwyer Jan 2000

A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 1: Pi Controller Tuning Rules, Aidan O'Dwyer

Conference papers

The ability of proportional integral (PI) and proportional integral derivative (PID) controllers to compensate many practical industrial processes has led to their wide acceptance in industrial applications. The requirement to choose either two or three controller parameters is perhaps most easily done using tuning rules. A summary of tuning rules for the PI control of single input, single output (SISO) processes with time delay is provided in this paper.

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A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 2: Pid Controller Tuning Rules, Aidan O'Dwyer Jan 2000

A Summary Of Pi And Pid Controller Tuning Rules For Processes With Time Delay. Part 2: Pid Controller Tuning Rules, Aidan O'Dwyer

Conference papers

The ability of proportional integral (PI) and proportional integral derivative (PID) controllers to compensate many practical industrial processes has led to their wide acceptance in industrial applications. The requirement to choose either two or three controller parameters is perhaps most easily done using tuning rules. A summary of tuning rules for the PID control of single input, single output (SISO) processes with time delay is provided in this paper.

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Successful Proposal Preparation, Mariesa Crow Jan 2000

Successful Proposal Preparation, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

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Two Separate Continually Online Trained Neurocontrollers For Excitation And Turbine Control Of A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley Jan 2000

Two Separate Continually Online Trained Neurocontrollers For Excitation And Turbine Control Of A Turbogenerator, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents the design of two separate continually online trained (GOT) artificial neural network (ANN) controllers for excitation and turbine control of a turbogenerator connected to the infinite bus through a transmission line. These neurocontrollers augment/replace the conventional automatic voltage regulator and the turbine governor of a generator. A third COT ANN is used to identify the complex nonlinear dynamics of the power system. Results are presented to show that the two COT ANN controllers can control turbogenerators under steady state as well as transient conditions and thus allow turbogenerators to operate more closely to their steady state stability …

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About Resonant Modes At The Shielded Dielectric Hemisphere, Sergey Kharkovsky, A. E. Kogut, Z. E. Eremenko, V. V. Kutuzov, Yuri F. Filipov Jan 2000

About Resonant Modes At The Shielded Dielectric Hemisphere, Sergey Kharkovsky, A. E. Kogut, Z. E. Eremenko, V. V. Kutuzov, Yuri F. Filipov

Electrical and Computer Engineering Faculty Research & Creative Works

The resonant modes, which are excited at the shielded dielectric hemisphere, are investigated by the theoretical and experimental methods. The low-Q-factor modes of air cavity and high-Q-factor whispering gallery modes of dielectric structure are existed together in the case of high radial index value. The Q-factor value of the whispering gallery modes of the shielded dielectric sphere with the certain correlation between the sizes of dielectric hemisphere and metal shield can be more great than the Q-factor of the whispering gallery modes of the similar open dielectric resonator.

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Doppler Estimation Using A Coherent Ultrawide-Band Random Noise Radar, Ram M. Narayanan, Muhammad Dawood Jan 2000

Doppler Estimation Using A Coherent Ultrawide-Band Random Noise Radar, Ram M. Narayanan, Muhammad Dawood

Department of Electrical and Computer Engineering: Faculty Publications

The University of Nebraska has developed an ultrawide- band (UWB) coherent random noise radar operating over the 1–2 GHz frequency range. The system achieves phase coherence by using heterodyne correlation of the received signal with a time-delayed frequency-shifted replica of the transmit waveform. Knowledge of the phase of the received signal and its time dependence due to target motion permits the extraction of the mean Doppler frequency from which the target speed can be inferred. Theoretical analysis, simulation studies, and laboratory measurements using a microwave delay line showed that it was possible to estimate the Doppler frequency from targets with …

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Sar Imaging Using Fully Random Bandlimited Signals, Dmitriy S. Garmatyuk, Ram M. Narayanan Jan 2000

Sar Imaging Using Fully Random Bandlimited Signals, Dmitriy S. Garmatyuk, Ram M. Narayanan

Department of Electrical and Computer Engineering: Faculty Publications

A coherent ultrawideband (UWB) random noise synthetic aperture radar (SAR) has been developed and tested at the University of Nebraska. It has been experimentally shown that this type of radar is capable of extracting the phase and the amplitude of the backscattered signal, thus enabling us to create target profiles in the frequency domain. The use of fully random waveforms (bandlimited noise) as the transmit signal is analyzed in this paper. A UWB signal model is developed and radar signal processing is simulated to yield statistical characteristics of image formation using stochastic waveforms. The influence of UWB signal characteristics on …

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