Engineering Commons^™

Numerical Simulation Of Clipping Distortion In Lightwave Catv Systems, Luay Al-Nadi

Theses

Clipping induced distortion is an essential limit for modulation depth and number of channels in subcarrier multiplexed lightwave video transmission systems. Two different types of laser clipping are compared (single-clipping vs. double-clipping). In this work, the distortion limits imposed by clipping effects, in both directly (single-clipping) and externally (double-clipping) modulated systems, are examined. Numerical simulations were performed to test the efficiency of Saleh's Model. A comparison of results with clipping induced distortion in directly modulated lightwave systems (single-clipping) and clipping induced distortion in externally modulated lightwave systems (double-clipping) is presented, it is shown through numerical simulation that the total non-linear …

Analysis Of Calibration, Robustness, Detection Of Space-Time Adaptive Rada Using Experimental Data, Murat O. Berin

Theses

Signal cancellation effects in adaptive array radar are studied under non ideal conditions when there is a mismatch between the true desired signal and the presumed theoretical desired signal. This mismatch results in decreased performance when the estimated correlation matrix has a large desired signal component. The performance of the sample matrix inversion (SMI) method is compared to the eigenanalysis-based eigencanceler method. Both analytical results and the processing on the experimental data from the Mountaintop Program, show that eigenanalysis-based adaptive beamformers have greater robustness to signal cancellation effects than the SMI method. Also, the calibration of the recorded data, and …

Implementation Of A Friction Estimation And Compensation Technique, Jayesh N. Amin

Theses

This thesis reports implementation of a friction estimation and compensation technique on a special laboratory apparatus. In this work, experimental results are reported for the Coulomb friction observer.

The Coulomb friction observer estimates the total friction present in a system, assuming it to be a constant function of velocity. An extension of the observer, utilizing a coupled velocity observer, is used when velocity is not measurable. A modification to the velocity observer is also implemented. Experimental results show a remarkable improvement in the friction estimates which are also compared to the actual friction measurements. The estimates are qualitatively similar to …

Gabor Expansion Of An Equivalent Dipole Antenna, Oksana Manzhura

Theses

The Gabor representation in the context of an aperture problem is an expansion of a radiated field in terms of a discrete set of linearly shifted and spatially rotated elementary Gaussian beams. The parameters that can be varied in this summation are the number of beams and corresponding beam widths. As the difficulty associated with the unique determination of the expansion coefficients was alleviated, the method has been successfully applied to one and two dimensional apertures. Although, the asymptotic evaluation of expansion functions has reduced the computational burden drasticallym it was at the expense of some loss in accuracy. The …

Small Computer System Interface (Scsi) Universal Services For The Turbonet Parallel Computer, Artak Ohan Melkonian

Theses

TurboNet is a parallel computer with shared-memory and message-passing hybrid architecture. It employs two boards, with four digital signal processors (DSPs) each, and a host FORCE SPARC CPU-2CE board with a SCSI bus.

Software has been developed in this thesis to provide SCSI services to programs running on the DSPs. DSP programs can therefore fully control assigned SCSI devices at the SCSI command level. Transfer control modifiers ensure compatibility with most SCSI devices.

The software provides service for three SCSI access levels. The "su" SCSI universal device driver is built into the host computer's kernel and is a gateway to …

Design And Development Of Four To Sixteen Channel Video Multiplexers, Ronan Rahimi

Theses

Video multiplexer series were successfully designed and built for prototype and evaluation both in terms of hardware and software. The hardware platform was designed to accommodate up to sixteen color video input channels for time lapse or real time recording on a single video cassette recorder. This product implements four modes of operation; Live, Record, Playback and Menu mode, which is not a full mode of operation. Menu mode is a series of on-screen programming menus which appears on Live, Record and Playback modes. Menu mode enables the user to program the machine to work under specific modes of application. …

The Development Of An Embedded Wireless Modem Conforming To Advanced Mobile Phone System And Cellular Digital Packet Data Standards, Xin Ren

Theses

Introduced by AT&T Bell Labs in 1970s, today Advanced Mobile Phone Systems (AMPS) - a first generation analog cellular system serve millions of customers in the United States and 55 other countries, and the number of subscribers is still rapidly increasing. Although digital cellular systems are emerging in recent years, research efforts are still being made to the enhancement of AMPS systems because of their popularity. An example is the new Cellular Digital Packet Data (CDPD) standard announced in 1994. CDPD is an overlay of the existing AMPS, and has the capability of transmitting data packets over such an analog …

Configuring The Radial Basis Function Neural Network, Insoo Sohn

Theses

The most important factor in configuring an optimum radial basis function (RBF) network is the training of neural units in the hidden layer. Many algorithms have been proposed, e.g., competitive learning (CL), to train the hidden units. CL suffers from producing "dead-units." The other major factor Which was ignored in the past is the appropriate selection of the number of neural units in the hidden layer. The frequency sensitive competitive learning (FSCL) algorithm was proposed to alleviate the problem of dead-units, but it does not alleviate the latter problem. The rival penalized competitive learning (RPCL) algorithm is an improved version …

Linearly Tapered Slot Antenna, Luis Alberto Tumialan

Theses

Design procedure for Linearly Tapered Slot Antennas (LTSA) has been developed and implemented using High Frequency Structure Simulator (HFSS) code based on a finite-element analysis.

A CAD study of two variations of a LISA based on either a stripline or a microstrip feed has been carried out. Circular and radial stubs have been considered in these designs for an antenna operating at 10 Ghz. LTSA on a Duroid substrate fed by a stripline has been designed to operate with better than 12 dB return loss. Fabricated antenna was characterized and had even a wider response than the CAD design. Radiation …

Adaptive Radar In Heterogeneous Environment, Albert Futernik

Theses

Radar performance in heterogeneous clutter has been a much studied topic. In all the studies so far, various forms of the sample matrix inversion (SMI) technique where used to calculate the weight vector of the processor. In this thesis an eigenanalysis-based technique known as the eigencanceler, is used. Performance of this technique is compared to the performance of the generalized likelihood ration (GLR) processor. This comparison is done using the clutter edge model, in which there is an abrupt change in the clutter power in the reference window. It is shown that the false alarm rate fluctuations, of the cell …

A Comparative Study Of Image Compress Schemes, Kui Wang

Theses

Image compression is an important and active area of signal processing. All popular image compression techniques consist of three stages: Image transformation, quantization (lossy compression only), and lossless coding (of quantized transform coefficients).

This thesis deals with a comparative study of several lossy image compression techniques. First, it reviews the well-known techniques of each stage. Starting with the first stage, the techniques of orthogonal block transformation and subband transform are described in detail. Then the quantization stage is described, followed by a brief review of the techniques for the third stage, lossless coding.

Then these different image compression techniques are …

Translation Of 'Profiles In Faith', Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

Sarat Chandra Chatterjee (1876-1938) may be considered one of the three most significant figures of the literary component of the Bengal Renaissance, the other two being Bankim Chandra Chatterjee (1838-1894) and Rabindranath Tagore (1861-1941). As much as Bankim Chandra is identified with the new age in the Bengali novel, and the development of serious vernacular journalism, and Rabindranath with modern/classical movements in Bengali poetry and music, along with novel ideas in methods of education and teaching, Sarat Chandra, as a novelist and storyteller, perfected the art of narration and critical analyses of a variety of contemporaneous social and political issues, …

A Simulation Environment For Cdma Wireless Communication Systems In Awgn Channels, Muzaffer Kanaan

Theses

The goal of this work is the development of a, wireless communication system simulator. The simulator has been developed primarily to aid in the studies of Code Division Multiple Access (CDMA) digital cellular systems. We begin by introducing the fundamentals of spread spectrum communications and the motivation for this work. We then take a detailed look at CDMA systems and their structure. We then verify the accuracy of the simulator by using it to simulate some familiar system scenarios. We end this work by presenting conclusions and suggestions for further work.

Flash Adc Using 2Μm Cmos P-Well Technology : Design And Test, Joseph E. Levinson

Theses

This thesis describes the design, implementation and test for a new CMOS analog-to-digital converter IC chip. In designing the analog-to-digital converter in this thesis a radically different comparator design that is only available with CMOS logic. The design utilizes a single CMOS inverter as an ultra-high gain amplifier. This approach reduces the circuit dependence upon matching of the transistors similar to the traditional method. This new design requires less area since the comparator utilizes fewer transistors.

Flash analog-to-digital converters use 2" - 1 comparators to do a single conversion where n is the number of bits used. These comparators are …

Asynchronous Multiuser Decorrelating Detector For Awgn Channel, Ashwini A. Borkar

Theses

Decorrelating detector is one of the sub-optimum detectors for CDMA applications that generally has better performance than the conventional detector and is near-far resistant. Synchronous decorrelating detector employing DPSK modulation is considered and its simulation results are presented.

Attention is focussed on one-shot decorrelating detector for a two user case for asynchronous transmission, where each symbol interval is considered seperately. Initially the performance of the detector with exact estimation of the relative delay is analyzed and then the effect of inaccurate estimation on the probability of error is discussed.

Binary Gas Mixture Analysis With An Interdigitated Gate Electrode Field Effect Transistor (Igefet) Microsensor, John M. Wiseman

Theses and Dissertations

Single component and binary gas mixtures of nitrogen dioxide (NO2) and ammonia (NH3) were analyzed with a microsensor composed of an array of interdigitated Gate Electrode Field Effect Transistor (IGEFET) sensor elements coated with copper-, nickel-, and cobalt-phthalocyanine thin films. Improvements in the IGEFET microsensor design and operation facilitated simultaneous measurement of ihe direct current (DC) and alternating current (AC) electrical response of the metal-substituted phthalocyanine (MPc) films to challenge gas exposure. A finite-difference model of the interdigitated gate electrode (IGE) structure confirmed the fundamental operation of the IGEFET microsensor. Principal component analysis (PCA) and multilinear regression were applied to …

Maximum Likelihood Estimation Of Wave Front Slopes Using A Hartmann-Type Sensor, Scott A. Sallberg

Theses and Dissertations

Current methods for estimating the wave front slope at the pupil of a telescope equipped with a Hartmann-type wave front sensor (H-WFS) are based on a simple centroid calculation of the intensity distributions (spots) recorded in each subaperture of the H-WFS. The centroid method does not include any knowledge concerning correlation properties of the slopes over the subapertures or the amount of light collected by the telescope and diverted to the H-WFS for wave front reconstruction purposes. This thesis devises a maximum likelihood (ML) estimation of the spot centroids by incorporating statistical knowledge of the spot shifts. The light level …

Improving The Morse Intercept Operator's Audio Display, Jesse M. Washburn

Theses and Dissertations

This thesis improves the audio display for multiple Morse communications. Factors considered to improve the audio display are frequency of source, volume level of source, and methods of unmasking. The best frequency and volume level of a Morse source is 500 Hz at 70 dB sound pressure level (spi). Two types of masking are researched: frequency masking and expectation driven masking. Experiments showed by amplifying high pitched sources the effects of frequency masking are minimized. Other methods to compensate for frequency masking are 3-D sound and the placement of a source out of phase between the ears. Morse code recognition …

Effects Of Neutron Radiation On Resonant Cavity Light-Emitting Diodes, Daniel S. Hinkel

Theses and Dissertations

Resonant Cavity Light Emitting Diodes (RCLEDs) were irradiated in Ohio State University's nuclear reactor to determine the effects of Neutron displacement damage. The RCLEDs were characterized both before and after irradiation by their current versus voltage curves (I-V curves) and external light power versus current curves (L-I curves). The I-V curves showed an increase in the "knee voltage" at a neutron fluence of 1.45x10¹⁷ neutrons/cm2. Logarithmic decreases in external light power and differential quantum efficiency were observed. Significant decreases in external light power were observed at neutron fluences greater than 5.1x10¹³ neutrons/cm². Equations were developed to …

Evaluation Of The Sensitivity Of Radar Cross Section Predictions To Uncertainties In Material Characteristics, Greg A. Barnhart

Theses and Dissertations

The purpose of this study was to evaluate the effects of material characteristics uncertainties on Radar Cross Section (RCS) predictions. Many methods have been developed to predict the RCS of metal objects, but for material coated objects, these methods depend on the accuracy of measured material characteristics. Material characteristics of three dielectrics were measured by two separate X-band waveguide set-ups. RCS measurements were then made to evaluate the accuracy of RCS predictions using these measured material characteristics. A six inch square slab of each material was measured with and without a metal plate backing. A six inch square flat metal …

Algorithms For The Njit Turbonet Parallel Computer, Nitin J. Lad

Theses

Element selection for arrays, array merging, and sorting are very frequent operations in many of today's important applications. These operations are of interest to scientific, as well as other applications where high-speed database search, merge, and sort operations are necessary and frequent. Therefore, their efficient implementation on parallel computers should be a worthwhile objective. Parallel algorithms are presented in this thesis for the implementation of these operations on the NET TurboNet system, an in-house built experimental parallel computer with TMS320C40 Digital Signal Processors interconnected in a 3-D hypercube structure. The first algorithm considered is selection. It involves finding the k-th …

Extreme Ultraviolet Polarizing Optics Using Bare And Aluminum-Coated Silicon Carbide, R. M.A. Azzam, A. M. Kan’An

Electrical Engineering Faculty Publications

A deformable three-reflection system that uses a bare silicon carbide substrate can function as an in-line, high-throughput (>30%), 90° phase shifter in the 50–100 nm spectral range. For a given extreme ultraviolet wavelength, an aluminum thin film can be deposited on the silicon carbide substrate to suppress the parallel (p) or perpendicular (s) polarization on single reflection or to introduce quarter-wave retardation and equal reflectances for incident p- and s-polarized light.

Optimal Inputs For System Identification, James M. Brown Ii

Theses and Dissertations

The derivation of the power spectral density of the optimal input for system identification is addressed in this research. Optimality is defined in information theoretic terms, with entropy quantifying the parameter information content of the input and output measurement sequences pertaining to a discrete time plant. The maximization of entropy is performed in the context of three different scenarios. First, the case in which the average output power of the plant is constrained is considered. Second, input average power is constrained. Finally, the optimization is carried out unconstrained, but with penalties applied to both the input and output powers. Although …

Broadband Dynamic, Holographically Self-Recorded, And Static Hexagonal Scattering Patterns In Photorefractive Knbo3:Fe, Nickolai Kukhtarev, Tatiana V. Kukhtareva, John Caulfield, Partha P. Banerjee, Hsueh-Ling Yu, Lambertus Hesselink

Electrical and Computer Engineering Faculty Publications

We have observed and explained three types of hexagon pattern formation in photo refractive crystal KNb03:Fe. These are:

• Dynamic (laser induced)
• Semipermanent (holographically stored)
• Permanent (induced by a static domain grid) over a wide wavelength range

Transient Wave Mixing And Recording Kinetics In Photorefractive Barium Titanate: A Nonlinear Coupled Mode Approach, Partha P. Banerjee, John M. Jarem

Electrical and Computer Engineering Faculty Publications

By using rigorous coupled-wave diffraction theory along with a time-dependent nonlinear formulation, we analyze two- and multiplewave coupling and the grating kinetics in BaTi03 with different boundary interfaces. Efffects of electrostatic and optical anisotropy have been included in the analysis. Significant mode conversion to higher orders is observed only when the boundary interfaces are highly mismatched.

Guest Editorial: Special Section On Photorefractive Nonlinear Optics, Partha P. Banerjee

Electrical and Computer Engineering Faculty Publications

Hand in hand with experimental work in photorefractives, there is a lot of activity in modeling photorefractive materials and experimental observations in the open literature. This special section contains a paper by Banerjee and Jarem, who use a rigorous coupled wave theory to analyze two- and multiple-wave mixing photorefractive barium titanate, modeled through the Kukhtarev equations.

Single-Layer-Coated Surfaces With Linearized Reflectance Versus Angle Of Incidence: Application To Passive And Active Silicon Rotation Sensors, R. M.A. Azzam, M. M. K. Howlader, T. Y. Georgiou

Electrical Engineering Faculty Publications

A transparent or absorbing substrate can be coated with a transparent thin film to produce a linear reflectanceversus- angle-of-incidence response over a certain range of angles. Linearization at and near normal incidence is a special case that leads to a maximally flat response for p-polarized, s-polarized, or unpolarized light. For midrange and high-range linearization with moderate and high slopes, respectively, the best results are obtained when the incident light is s polarized. Application to a Si substrate that is coated with a SiO₂ film leads to novel passive and active reflection rotation sensors. Experimental results and an error analysis …

Seasonal Hidden Markov Models For Stochastic Time Series With Periodically Varying Characteristics, Arthur M. Lewis

Dissertations and Theses

Novel seasonal hidden Markov models (SHMMs) for stochastic time series with periodically varying characteristics are developed. Nonlinear interactions among SHMM parameters prevent the use of the forward-backward algorithms which are usually used to fit hidden Markov models to a data sequence. Instead, Powell's direction set method for optimizing a function is repeatedly applied to adjust SHMM parameters to fit a data sequence. SHMMs are applied to a set of meteorological data consisting of 9 years of daily rain gauge readings from four sites. The fitted models capture both the annual patterns and the short term persistence of rainfall patterns across …

Determination Of The Temperature Coefficients Of Selected Material Constants Of Dilithium Tetraborate, Gregory S. Weaver

Theses and Dissertations

The first and second order temperature coefficients of the material constants c^E₁₁, c^E₁₂, c^E₄₄, c^E₆₆, and e¹⁵ of dilithium tetraborate (Li₂B₄O₇) have been measured over a temperature range of 20°C to 150°C. An improved resonator method was used to measure the fundamental zero mass loading antiresonant frequencies of selected pure-mode orientations of Li₂B₄O₇. Material constants extraction was performed using a linear least squares matrix method. The resulting material constant curves were fit with a third …

Design, Fabrication, Modeling, And Testing Of Surface-Micromachined Micromirror Devices, M. Adrian Michalicek

Theses and Dissertations

The Flexure-Beam Micromirror Device (FBMD) is a phase-only piston style spatial light modulator demonstrating properties which can be used for phase adaptive- corrective optics. This thesis presents a complete study of new designs of FBMDs and other micromirror devices, from original design considerations through final device testing and verification of ideal and advanced models. The models relate the electrical and mechanical properties of the device by equating the electrostatic force of a parallel- plate capacitor with the counteracting spring force of the device's support flexures. For the advanced model of the Flexure-Beam micromirror device, the capacitor solution is derived via …