Engineering Commons^™

Phase-Sensitive Detection Electronics For Wavelength Modulation Spectroscopy Experiments, Tyrone Pate

Electrical & Computer Engineering Theses & Dissertations

Wavelength modulation spectroscopy (WMS) is a non-intrusive detection technique, which enables the measurement of several parameters such as pressure, concentration, and temperature of a species of interest by analyzing the latter's absorption lineshape profile. The method employs a synchronous modulation and detection apparatus to increase the signal to noise ratio and hence the sensitivity of the measurement. Phase-sensitive detection and demodulation of the signal is performed at the modulation frequency and its harmonics. Research at ODU demonstrates that each particular measurement can be performed optimally at an appropriate harmonic of the modulation frequency. The most suitable harmonic depends on many …

Adaptive Ds-Cdma Multiuser Detection For Time Variant Frequency Selective Rayleigh Fading Channel, Xin Tang

Dissertations

The current digital wireless mobile system such as IS-95, which is based on direct sequence Code Division Multiple Access (DS-CDMA) technology, will not be able to meet the growing demands for multimedia service due to low information exchanging rate. Its capacity is also limited by multiple accessed interference (MAI) signals.

This work focuses on the development of adaptive algorithms for multiuser detection (MUD) and interference suppression for wideband direct sequence code division multiple access (DS-CDMA) systems over time-variant frequency selective fading channels. In addition, channel acquisition and delay estimation techniques are developed to combat the uncertainty introduced by the wireless …

Multicast Outing Protocols And Architectures In Mobile Ad-Hoc Wireless Networks, Beongku An

Dissertations

The basic philosophy of personal communication services is to provide user-to-user, location independent communication services. The emerging group communication wireless applications, such as multipoint data dissemination and multiparty conferencing tools have made the design and development of efficient multicast techniques in mobile ad-hoc networking environments a necessity and not just a desire. Multicast protocols in mobile adhoc networks have been an area of active research for the past few years.

In this dissertation, protocols and architectures for supporting multicast services are proposed, analyzed and evaluated in mobile ad-hoc wireless networks. In the first chapter, the activities and recent advances are …

Em-Based Iterative Channel Estimation And Sequence Detection For Space-Time Coded Modulation, Zbigniew Baranski

Dissertations

Reliable detection of signals transmitted over a wireless communication channel requires knowledge of the channel estimate. In this work, the application of expectationmaximization (EM) algorithm to estimation of unknown channel and detection of space-time coded modulation (STCM) signals is investigated. An STCM communication system is presented which includes symbol interleaving at the transmitter and iterative EM-based soft-output decoding at the receiver. The channel and signal model are introduced with a quasi-static and time-varying Rayleigh fading channels considered to evaluate the performance of the communication system. Performance of the system employing Kalman filter with per-survivor processing to do the channel estimation …

On Chip Implement Of Deadlock Avoidance In Wormhole Networks, Kiran K. Gururaj

Theses

This thesis gives a detailed description of the Application Specific Integrated Circuit (ASIC) design to avoid deadlocks in Wormhole Networks. Deadlock avoidance is the most critical issue while considering wormhole networks and should be avoided by any routing protocol and algorithm. A novel architecture for the Turn Prohibition Based Routing (TPBR) protocol has been proved to be efficient and was developed as a part of this work. This architecture for implementing the algorithm is divided into three parts. The first part determines the order of selccuon of the nodes, in the network to run the algorithm. The second part deals …

Complementary Bodydriving - A Low-Voltage Analog Circuit Technique Realized In 0.35um Soi Process, Yong Leekee

Masters Theses

This thesis presents a study of several analog circuit primitives that utilize the body terminal as a signal port to achieve low-voltage operation and high performance. Several issues relating to low-voltage applications as well as the trends of technology scaling in the near future are presented. Principles of the body-driven transistor for both PMOS and NMOS in PDSOI technology are described, and critical design considerations are discussed. The design of low-voltage analog primitives (cascode current mirror and differential pair) are described and analyzed in detail. A discussion of the design and analysis of a 4-quadrant analog multiplier is also presented. …

A Lock-In Amplifier For Fluorescent Light Detection, Osman Oguz

Masters Theses

An integrated on-chip lock-in amplifier has been developed for fluorescent light detection for biological applications. The system includes 2.1 mm x 2.1 mm tiny chip using a photodiode transimpedance amplifier topology for the pre-amp, followed by gain amplifier, demodulator and filtering stages. Synchronous demodulator or phase sensitive detector stage has two different architectures to demonstrate the difference between the results. The recommended transmitting light frequency is between 0.5 kHz to 5 kHz. We used 1 kHz frequency for the test.

Theory And Design Of Mixed Lumped-Distributed Cross-Coupled Filters With Applications To Linear Phase Shifter And Tunable Filters, Sanghoon Shin

Dissertations

Using cross-coupled networks of a new concept, transmission zeros were efficiently located in the complex frequency-domain. With this approach, the group delay and attenuation slope of the circuit network can be controlled to get both sharp rejection characteristics and linear phase slopes. In order to achieve this performance, various types of combline filters are suggested. Various simulation tools (commercial linear circuit and E-M simulators), as well as the developed pole-zero locator program, were used to design a new class of cross-coupled networks. In particular, the polezero locator program can be used to extract an equivalent circuit of the topology that …

Experimental Studies Of Wave Propagation In Three-Dimensional Photonic Crystals, John M. Tobias

Dissertations

Photonic crystals were proposed fifteen years ago. Propagation is selectively prevented through these crystals resulting in a photonic band gap, that is, a frequency region where light cannot propagate. These frequency bands are analogous to electronic band gaps in solid-state crystals.

The optical properties of the photonic crystal in regions near the band gap remain relatively unexplored. Yet, there is significant evidence to suggest that this avenue of investigation can provide useful optical and microwave applications. Numerical studies have predicted that the effective permittivity near the photonic band gap approaches zero and becomes negative. Selfcollimation of the propagating beam and …

Stereo Matching Algorithm By Propagation Of Correspondences And Stereo Vision Instrumentation, Peerajak Witoonchart

Theses

A new image processing method is described for measuring the 3-D coordinates of a complex, biological surface. One of the problems in stereo vision is known as the accuracy-precision tradeoff problem. This thesis proposes a new method that promises to solve this problem. To do so, two issues are addressed. First, stereo vision instrumentation methods are described. This instrumentation includes a camera system as well as camera calibration, rectification, matching and triangulation. Second, the approach employs an array of cameras that allow accurate computation of the depth map of a surface by propagation of correspondences through pair-wise camera views.

The …

Determination Of Phase Composition Of Sputtered Tantalum On Steel Substrates By Resistivity Measurements, Younes Abbassi

Theses

The objective of this thesis was to develop a method of distinguishing between alpha and beta phases of tantalum films on steel substrates, using the four-point probe resistivity measurements. While there is a large difference between resistivities of the two Ta phases, the problem is challenging because the measurements are influenced by the low resistivity of steel.

For reference, the resistivity measurements of tantalum coatings (1-20 μm) on silicon and silicon dioxide substrates were conducted first. The measured resistivities were related to the crystallographic phase composition of Ta, which has lower resistivity in bcc form, α-phase, (13.5 to 42 μΩcm), …

Recent Advances In Silicon Light Emitting Diodes, Aravind Balakrishnan

Theses

A silicon based light emitting diode (LED) is a new gateway for combining optoelectronics with CMOS integrated circuits. The choice of silicon is limited due to its indirect band gap nature. There are new approaches for improving emission efficiencies in Si-LED to nearly 1% at room temperature. Boron implantation has been employed to introduce dislocation array and as a p-type dopant to form p-n Junction in an n-type Si substrate. The device operates as a conventional LED under forward bias. The temperature dependence of radiative recombination rate is addressed by Varshni empirical formula. The difference between the energy at which …

Evaluation And Analysis Of Array Antennas For Passive Coherent Location (Pcl) Systems, Baris Calikoglu

Theses and Dissertations

Passive Coherent Location (PCL) systems use a special form of a radar receiver that exploits the ambient radiation in the environment to detect and track targets. Typical transmissions of opportunity that might be exploited include television and FM radiobroadcasts. PCL implies the use of a non-radar electromagnetic sources of illumination, such as commercial radio or television broadcasts also referred as transmitters of opportunity. The use of such illumination sources means that the receiver needs to process waveforms that are not designed for radar purposes. As a consequence, the receivers for PCL systems must be much more customized than traditional receivers, …

Development And Characterization Of An Emergency Communications System Using Near Vertical Incident Skywave Antennas, Richard A. Allnutt

Theses and Dissertations

The NVIS system characterized in this work was designed to eliminate skip propagation by optimizing the design for contiguous coverage. The NVIS technique involves use of transmission and receiving antennas that create nearly vertical propagation and continuous coverage from the transmitter to a distance of 200 miles. Man portable, very low power transceivers (5 watts maximum) and horizontal dipole antennas five feet above the ground are used in an NVIS communication system for this work. The system is designed for the purpose of supporting communication with emergency workers in areas where other communication is difficult. Digital and analog effectiveness are …

On Performance Analysis And Implementation Issues Of Iterative Decoding For Graph Based Codes, Xuefei Wei

Dissertations

There is no doubt that long random-like code has the potential to achieve good performance because of its excellent distance spectrum. However, these codes remain useless in practical applications due to the lack of decoders rendering good performance at an acceptable complexity. The invention of turbo code marks a milestone progress in channel coding theory in that it achieves near Shannon limit performance by using an elegant iterative decoding algorithm. This great success stimulated intensive research oil long compound codes sharing the same decoding mechanism. Among these long codes are low-density parity-check (LDPC) code and product code, which render brilliant …

On The Data Hiding Theory And Multimedia Content Security Applications, Litao Gang

Dissertations

This dissertation is a comprehensive study of digital steganography for multimedia content protection. With the increasing development of Internet technology, protection and enforcement of multimedia property rights has become a great concern to multimedia authors and distributors. Watermarking technologies provide a possible solution for this problem.

The dissertation first briefly introduces the current watermarking schemes, including their applications in video,, image and audio. Most available embedding schemes are based on direct Spread Sequence (SS) modulation. A small value pseudo random signature sequence is embedded into the host signal and the information is extracted via correlation. The correlation detection problem is …

Renegotiation Based Dynamic Bandwidth Allocation For Selfsimilar Vbr Traffic, Zafer Sahinoglu

Dissertations

The provision of QoS to applications traffic depends heavily on how different traffic types are categorized and classified, and how the prioritization of these applications are managed. Bandwidth is the most scarce network resource. Therefore, there is a need for a method or system that distributes an available bandwidth in a network among different applications in such a way that each class or type of traffic receives their constraint QoS requirements.

In this dissertation, a new renegotiation based dynamic resource allocation method for variable bit rate (VBR) traffic is presented. First, pros and cons of available off-line methods that are …

Hyperbolic Position Location Estimator With Tdoas From Four Stations, Sreeram Potluri

Theses

This thesis presents a detailed derivation of a set of equations needed to locate the three dimensional position of a mobile given the locations of four fixed stations (like a global positioning system (GPS) satellite or a base station in a cell) and the signal time of arrival (TOA) from the mobile to each station. From these derived equations, a synthesizable VHDL model was developed and simulated using IEEE numen*c_std package. All the inputs and outputs were described by 32 bit vectors. From the simulations, it was observed that in the best case the mobile position was off by I …

Qos Routing Source Routing Problems And Solutions, Ye Tian

Theses

The notion of Quality-of-Service has been proposed to capture qualitatively or quantitatively defined performance contracts between the service provider and the user applications. Integrated network services are designed to support Quality-of-Service (QoS). One of the primary goals for the integrated network services is to find the paths that satisfy given QoS requirements, namely QoS routing. The challenging issue in this area is to route packets subjected to multiple uncorrelated constraints because the problem is inherently NP-complete. This thesis studies the source routing heuristic approaches that bring the time complexity down to the polynomial-time for the multi-constrained path (MCP) problem. A …

Robust Generalised Predictive Control - An Optimal Design For Uncertain Systems, Thomas O'Mahony

Theses

One of the more popular model predictive control approaches, of late, is the generalised predictive controller (GPC). It has received widespread dissemination in academia and numerous successful applications in industry testify to its usefulness. Its popularity partly stems from its superiority over its predecessors, its simplicity and its control acumen. However, since GPC is based on a mathematical model of the process, significant deterioration in performance or even closed-loop instability may arise due to the inevitable discrepancies that arise between the model and the true system. To ensure that the loop stability is not compromised and an adequate level of …

Design Of Low Phase Drift Cmos Frequency Synthesisers, Cyril Patrick Hervé Florent Lahuec

Theses

This thesis presents a methodology for the development of high performance video clock synthesisers that have high (2000) input to output clock multiplication ratios. The synthesisers are required to be compatible with standard CMOS technologies and they must exhibit very low drift between their input and output clocks.

The methodology used borrows techniques established for RF synthesisers in the GHz range. In the RF domain there are significant constraints on spectral spread and because of this there has been significant interest in phase noise generated by intrinsic device noise. Simple and accurate models were developed that help understand the up …

Design And Analysis Of Radio Frequency Deployment Algorithms For Gsm, Mónica Pérez-Carbonell

Theses

Due to the growth of the subscriber base and the introduction of new services, mobile communications networks’ demand for wireless resources is increasing. This has resulted in an increasing need to change the frequency allocation of a network in order to adapt the cellular network to new frequency demands.

Currently, a planning tool generates a new frequency plan, which is. then deployed to cell sites. The deployment should ideally be carried out with minimum disruption to network operation, which makes this deployment process a critical undertaking as any errors during or after the deployment can leave the network with poor …

Servo Response And Modelling Issues In Generalised Predictive Control, Ben Griffin

Theses

One of the more popular control strategies, of late, is the Generalised Predictive Controller (GPC). It has received widespread dissemination in academia and numerous successful applications in industry testify to its usefulness. Its popularity partly stems from its superiority to its predecessors, e.g. the generalised minimum variance and pole-placement controllers, but also from the GPC ‘tuning knobs’, which have simple time-domain interpretations and extremely robust default settings. However, despite the widespread interest, there would appear to be some issues relating to the specification of the closed-loop serv^o response that have not been covered in any great detail in the GPC …

Extensible Data Storage And Presentation Technology For An Ophthalmology Electronic Patient Record, Markus H. Heinrichs

Theses

The Electronic Patient Record (EPR) is a central element of practice systems used in ophthalmology. It acts as a repository for multi-media patient care data as well as billing information, serving healthcare providers and ultimately their patients. The aim of this thesis is to create both a data structure and a flexible on-screen representation of an EPR for an ophthalmology practice, and to provide an XML-based experimental prototype as a “proof of concept” which could ultimately be used as an replacement for an existing DOS- based solution. The medical background and requirements for this system will be described. The state-of-the-art …