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Analysis And Design Of Low-Jitter Oscillators, Justin Jennings Fitzpatrick Mar 2004

Analysis And Design Of Low-Jitter Oscillators, Justin Jennings Fitzpatrick

Theses and Dissertations

This thesis presents an examination of the jitter performance of different oscillator types in the presence of flicker noise, white noise and power supply noise. Key results are achieved using time domain simulations to determine cycle jitter of several different oscillator architectures, semiconductor processes and component features. In the end, a design procedure is developed for creating a low-jitter oscillator in a TSMC .25mm CMOS semiconductor process.

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Design Of A High Speed Mixed Signal Cmos Mutliplying Circuit, David Ray Bartholomew Mar 2004

Design Of A High Speed Mixed Signal Cmos Mutliplying Circuit, David Ray Bartholomew

Theses and Dissertations

This thesis presents the design of a mixed-signal CMOS multiplier implemented with short-channel PMOS transistors. The multiplier presented here forms the product of a differential input voltage and a five-bit digital code. A TSMC 0.18 µm MOSFET model is used to simulate the circuit in Cadence Design Systems. The research presented in this thesis reveals a configuration that allows the multiplier to run at a speed of 8.2 GHz with end-point nonlinearity less than 5%. The high speed and low nonlinearity make this circuit ideal for applications such as filtering and digital to analog conversion.

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A Linear Subspace Approach To Burst Communication Signal Processing, Daniel E. Gisselquist Mar 2004

A Linear Subspace Approach To Burst Communication Signal Processing, Daniel E. Gisselquist

Theses and Dissertations

This dissertation focuses on the topic of burst signal communications in a high interference environment. It derives new signal processing algorithms from a mathematical linear subspace approach instead of the common stationary or cyclostationary approach. The research developed new algorithms that have well-known optimality criteria associated with them. The investigation demonstrated a unique class of multisensor filters having a lower mean square error than all other known filters, a maximum likelihood time difference of arrival estimator that outperformed previously optimal estimators, and a signal presence detector having a selectivity unparalleled in burst interference environments. It was further shown that these …

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Evaluating The Navigation Potential Of The National Television System Committee Broadcast Signal, Ryan J. Eggert Mar 2004

Evaluating The Navigation Potential Of The National Television System Committee Broadcast Signal, Ryan J. Eggert

Theses and Dissertations

The accuracy and worldwide availability of the Global Positioning System (GPS) make it the dominant system for navigation and precise positioning. Unfortunately, many situations arise in which GPS may not be adequate, e.g., urban navigation. This research evaluates the navigation potential of the National Television System Committee (NTSC) broadcast signal using a time-difference-of-arrival (TDOA) algorithm. TDOA measurements are made using NTSC broadcast signals collected from low and high multipath environments. These measurements are then used to evaluate the severity and dynamic effects of NTSC broadcast multipath signals. Three data reduction algorithms were developed--one that modifies the classical cross-correlation TDOA approach, …

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Multiple Access Interference Characterization For Direct-Sequence Spread-Spectrum Communications Using Chip Waveform Shaping, Matthew G. Glen Mar 2004

Multiple Access Interference Characterization For Direct-Sequence Spread-Spectrum Communications Using Chip Waveform Shaping, Matthew G. Glen

Theses and Dissertations

This research characterizes MAI effects on DS/SSMA system performance through simulation in Matlab , and explores the impact of multiple access code selection, chip waveform shaping, and multiple access code length on BER for both synchronous and asynchronous multiple access networks. In addition, the simulated DS/SSMA model permits rapid research into the effects of additional factors on BER. Prior to experimental testing, model validation is conducted through single user trials and by comparison with existing research for similar system designs. For synchronous and asynchronous networks, Gold coding improves BER by 7.5 and 4.0 dB, respectively, relative to aperiodic random spreading …

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An Analysis Of Electromagnetic Interference (Emi) Of Ultra Wideband(Uwb) And Ieee 802.11a Wireless Local Area Network (Wlan) Employing Orthogonal Frequency Division Multiplexing (Ofdm), Juan Lopez Jr. Mar 2004

An Analysis Of Electromagnetic Interference (Emi) Of Ultra Wideband(Uwb) And Ieee 802.11a Wireless Local Area Network (Wlan) Employing Orthogonal Frequency Division Multiplexing (Ofdm), Juan Lopez Jr.

Theses and Dissertations

Military communications require the rapid deployment of mobile, high-bandwidth systems. These systems must provide anytime, anywhere capabilities with minimal interference to existing military, private, and commercial communications. Ultra Wideband (UWB) technology is being advanced as the next generation radio technology and has the potential to revolutionize indoor wireless communications. The ability of UWB to mitigate multipath fading, provide high-throughput data rates (e.g., greater than 100 Mbps), provide excellent signal penetration (e.g., through walls), and low implementation costs makes it an ideal technology for a wide range of private and public sector applications. Preliminary UWB studies conducted by The Institute for …

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Implementation Issues Of Real-Time Trajectory Generation On Small Uavs, Derek B. Kingston Mar 2004

Implementation Issues Of Real-Time Trajectory Generation On Small Uavs, Derek B. Kingston

Theses and Dissertations

The transition from a mathematical algorithm to a physical hardware implementation is non-trivial. This thesis discusses the issues involved in the transition from the theory of real-time trajectory generation all the way through a hardware experiment. Documentation of the validation process as well as modifications to the existing theory as a result of hardware testing are treated at length. The results of hardware experimentation show that trajectory generation can be done in real-time in a manner facilitating coordination of multiple small UAVs.

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Characterization Of Ultra Wideband Multiple Access Performance Using Time Hopped-Biorthogonal Pulse Position Modulation, Donald J. Clabaugh Mar 2004

Characterization Of Ultra Wideband Multiple Access Performance Using Time Hopped-Biorthogonal Pulse Position Modulation, Donald J. Clabaugh

Theses and Dissertations

The FCC's release of its UWB First Report and Order in April 2002 spawned renewed interest in impulse signaling research. This work combines Time Hopped (TH) multiple access coding with 4-ary UWB Biorthogonal Pulse Position Modulation (TH-BPPM). Multiple access performance is evaluated in a multipath environment for both synchronous and asynchronous networks. Fast time hopping is implemented by replicating and hopping each TH-BPPM symbol NH times. Bit error expressions are derived for biorthogonal TH-BPPM signaling and results compared with previous orthogonal TH-PPM work. Without fast time hopping (NH = 1), the biorthogonal TH-BPPM technique provided gains equivalent to Gray-coded QPSK; …

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Beamforming Techniques And Interference Mitigation Using A Multiple Feed Array For Radio Astronomy, Chad K. Hansen Mar 2004

Beamforming Techniques And Interference Mitigation Using A Multiple Feed Array For Radio Astronomy, Chad K. Hansen

Theses and Dissertations

Radio frequency interference has become a large problem to radio astronomers. This thesis proposes the idea that radio frequency interference can be mitigated using a phased array feed in conjunction with a large reflector. A phased array feed would allow radio astronomers to observe fainter signals than is currently possible, while at the same time enabling rapid sky surveys. A phased array feed was designed and simulated, and sensitivity optimization was performed on the array feed. It was shown that higher sensitivity can be achieved using a 7-element phased array feed than with a conventional waveguide feed. Simulations were ran …

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Method Of Non-Data-Aided Carrier Recovery With Modulation Identification, Kenta Umebayashi, Robert H. Morelos-Zaragoza, Ryuji Kohno Mar 2004

Method Of Non-Data-Aided Carrier Recovery With Modulation Identification, Kenta Umebayashi, Robert H. Morelos-Zaragoza, Ryuji Kohno

Faculty Publications

A non-data aided carrier recovery technique using digital modulation format identification called multi-mode PLL (Phase Locked Loop) is proposed. This technique can be interpreted as a modulation identification method that is robust against static phase and frequency offsets. The performance of the proposed technique is studied and the analytical expressions are derived for the probability of lock detection, acquisition time over AWGN channel in the cases of M-PSK and M-QAM modulations with respect to frequency offset and signal-to-noise ratio.

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A Differentiated Services Architecture For Quality Of Service Provisioning In Wireless Local Area Networks, Tristan Raimondi Mar 2004

A Differentiated Services Architecture For Quality Of Service Provisioning In Wireless Local Area Networks, Tristan Raimondi

Masters

Currently the issue of Quality of Service (QoS) is a major problem in IP networks due to the growth in multimedia traffic (e.g. voice and video applications) and therefore many mechanisms like IntServ, DiffServ, etc. have been proposed. Since the IEEE 802.11b (or Wi-Fi) standard was approved in 1999, it has gained in popularity to become the leading Wireless Local Area Network (WLAN) technology with millions of such networks deployed worldwide. Wireless networks have a limited capacity (11 Mbits/s in the case of Wi-Fi networks) owing to the limited amount of frequency spectrum available. At any given time there may …

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Analysis Of Electromagnetic Field Polarizations In Multi-Antenna Systems, Michael A. Jensen, Jon W. Wallace, Thomas Svantesson Mar 2004

Analysis Of Electromagnetic Field Polarizations In Multi-Antenna Systems, Michael A. Jensen, Jon W. Wallace, Thomas Svantesson

Faculty Publications

This paper provides an analytical framework useful for assessing the use of all six electric and magnetic electromagnetic field polarizations for multiantenna communications systems. The approach uses a mapping between the induced signal currents and the received electromagnetic field in order to formulate a diversity interpretation of the six-polarization problem. Application of the framework to a simple, yet representative, channel model demonstrates that for full multipath elevation and azimuthal angle spread, six communication modes are theoretically possible. However, to implement the system requires more antenna design work since a straightforward implementation is found to reduce the potential number of modes …

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Swarming Reconnaissance Using Unmanned Aerial Vehicles In A Parallel Discrete Event Simulation, Joshua J. Corner Mar 2004

Swarming Reconnaissance Using Unmanned Aerial Vehicles In A Parallel Discrete Event Simulation, Joshua J. Corner

Theses and Dissertations

Current military affairs indicate that future military warfare requires safer, more accurate, and more fault-tolerant weapons systems. Unmanned Aerial Vehicles (UAV) are one answer to this military requirement. Technology in the UAV arena is moving toward smaller and more capable systems and is becoming available at a fraction of the cost. Exploiting the advances in these miniaturized flying vehicles is the aim of this research. How are the UAVs employed for the future military? The concept of operations for a micro-UAV system is adopted from nature from the appearance of flocking birds, movement of a school of fish, and swarming …

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Optimization Of Heterogeneous Uav Communications Using The Multiobjective Quadratic Assignment Problem, Mark P. Kleeman Mar 2004

Optimization Of Heterogeneous Uav Communications Using The Multiobjective Quadratic Assignment Problem, Mark P. Kleeman

Theses and Dissertations

The Air Force has placed a high priority on developing new and innovative ways to use Unmanned Aerial Vehicles (UAVs). The Defense Advanced Research Projects Agency (DARPA) currently funds many projects that deal with the advancement of UAV research. The ultimate goal of the Air Force is to use UAVs in operations that are highly dangerous to pilots, mainly the suppression of enemy air defenses (SEAD). With this goal in mind, formation structuring of autonomous or semi-autonomous UAVs is of future importance. This particular research investigates the optimization of heterogeneous UAV multi-channel communications in formation. The problem maps to the …

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Swarm Based Implementation Of A Virtual Distributed Database System In A Sensor Network, Wen C. Lee Mar 2004

Swarm Based Implementation Of A Virtual Distributed Database System In A Sensor Network, Wen C. Lee

Theses and Dissertations

The deployment of unmanned aerial vehicles (UAVs) in recent military operations has had success in carrying out surveillance and combat missions in sensitive areas. An area of intense research on UAVs has been on controlling a group of small-sized UAVs to carry out reconnaissance missions normally undertaken by large UAVs such as Predator or Global Hawk. A control strategy for coordinating the UAV movements of such a group of UAVs adopts the bio-inspired swarm model to produce autonomous group behavior. This research proposes establishing a distributed database system on a group of swarming UAVs, providing for data storage during a …

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Geolocation Of An Audio Source In A Multipath Environment Using Time-Of-Arrival, Jeffrey A. Boggs Mar 2004

Geolocation Of An Audio Source In A Multipath Environment Using Time-Of-Arrival, Jeffrey A. Boggs

Theses and Dissertations

The Air Force and the Department of Defense (DoD) are continually searching for ways to protect U.S. forces, both stateside and abroad. One continuing threat, especially in the current world environment, is gunfire from an unseen sniper. Designated areas, such as a forward deployed base or motorcade route, need to be continuously monitored for sniper fire. Once detected, these gunmen need to be located in real time. One possible method for accomplishing this task is to geolocate the audio signals generated using time-of-arrival (TOA) algorithms. These algorithms rely on direct-path measurements for accuracy. Multipath environments therefore pose a problem when …

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Atmospheric Simulation Using A Liquid Crystal Wavefront Controlling Device, Matthew R. Brooks Mar 2004

Atmospheric Simulation Using A Liquid Crystal Wavefront Controlling Device, Matthew R. Brooks

Theses and Dissertations

Test and evaluation of laser warning devices is important due to the increased use of laser devices in aerial applications. In this thesis, an atmospheric aberrating system is developed to enable in-lab testing of laser warning devices. This system employs laser light at 632.8nm from a Helium-Neon source and a spatial light modulator (SLM) to cause phase changes using a birefringent liquid crystal material. Before the system can be used, the SLM phase response must be quantified to ensure proper manipulation of index of refraction. Additionally, diffraction from the SLM and real-world system scaling are addressed. Once completed, the atmospheric …

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Target Recognition Using Linear Classification Of High Range Resolution Radar Profiles, Ricardo A. Diaz Mar 2004

Target Recognition Using Linear Classification Of High Range Resolution Radar Profiles, Ricardo A. Diaz

Theses and Dissertations

High Range Resolution (HRR) radar profiles map three-dimensional target characteristics onto one-dimensional signals that represent reflected radar intensity along target extent. In this thesis, second through fourth statistical moments are extracted from HRR profiles and input to Fisher Linear Discriminant (FLD) classifiers. An iterative classification process is applied that gradually minimizes required a priori knowledge about the target data. It is found that the second through fourth statistical moments of HRR profiles are useful features in the FLD classification of dissimilar targets and they provide reasonable discrimination of similar targets. Greater than 69% correct classification for two-target scenarios and greater …

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Thin Film Encapsulation Of Radio Frequency (Rf) Microelectromechanical Systems (Mems) Switches, Eric D. Marsh Mar 2004

Thin Film Encapsulation Of Radio Frequency (Rf) Microelectromechanical Systems (Mems) Switches, Eric D. Marsh

Theses and Dissertations

Microelectromechanical systems (MEMS) radio frequency (RF) switches have been shown to have excellent electrical performance over a wide range of frequencies. However, cost-effective packaging techniques for MEMS switches do not currently exist. This thesis involves the design of RF-optimized encapsulations consisting of dielectric and metal layers, and the creation of a novel thin film encapsulation process to fabricate the encapsulations. The RF performance of several encapsulation designs are evaluated with an analytical model, full wave electromagnetic simulation, and laboratory testing. Performance degradation due to parasitic and reflection losses due to the package is considered, and RF feed-throughs of the transmission …

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Microprocessor-Based Systems Control For The Rigidized Inflatable Get-Away-Special Experiment, David C. Moody Mar 2004

Microprocessor-Based Systems Control For The Rigidized Inflatable Get-Away-Special Experiment, David C. Moody

Theses and Dissertations

As the demand for space based communications and faster data throughput increase, satellites are becoming larger. Larger satellite antennas help to provide the needed gain to increase communications in space. Compounding the performance and size trade-offs are the payload weight and size limit imposed by the launch vehicles. Inflatable structures offer a cost saving opportunity since the structure is significantly lighter and has a reduced storage volume. This allows for smaller launch vehicles and for increased performance capabilities. Inflatable structures offer possibilities for increased satellite lifetimes, increased communications capacity, and reduce launch costs. This thesis develops and implements the computer …

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Enhancing The Instantaneous Dynamic Range Of Electronic Warfare Receivers Using Statistical Signal Processing, Bryan E. Smith Mar 2004

Enhancing The Instantaneous Dynamic Range Of Electronic Warfare Receivers Using Statistical Signal Processing, Bryan E. Smith

Theses and Dissertations

Accurately processing multiple, time-coincident signals presents a challenge to Electronic Warfare (EW) receivers, especially if the signals are close in frequency and/or mismatched in amplitude. The metric that quantifies an EW receiver's ability to measure time-coincident signals is the Instantaneous Dynamic Range (IDR), defined for a given frequency estimation accuracy, a given frequency separation and a given SNR as the maximum signal amplitude ratio that can be accommodated. Using a two sinusoid time-series model, this thesis analyzes IDR for ideal intercept and parametric digital EW receivers. In general, the number of signals contained in the EW receiver measurement interval is …

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Demonstrating Optothermal Actuators For An Autonomous Mems Microrobot, Francis R. Szabo Mar 2004

Demonstrating Optothermal Actuators For An Autonomous Mems Microrobot, Francis R. Szabo

Theses and Dissertations

There are numerous applications for microrobots which are beneficial to the Air Force. However, the microrobotics field is still in its infancy, and will require extensive basic research before these applications can be fielded. The biggest hurdle to be solved, in order to create autonomous microrobots, is generating power for their actuator engines. Most present actuators require orders of magnitude more power than is presently available from micropower sources. To enable smaller microrobots, this research proposed a simplified power concept that eliminates the need for on-board power supplies and control circuitry by using actuators powered wirelessly from the environment. This …

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An Analysis Of The Effects Of Low Energy Electron Radiation Of AlXGa1-XN/Gan Modulation-Doped Field-Effect Transistors, James M. Sattler Mar 2004

An Analysis Of The Effects Of Low Energy Electron Radiation Of AlXGa1-XN/Gan Modulation-Doped Field-Effect Transistors, James M. Sattler

Theses and Dissertations

The effects of radiation on AlxGa1-xN/GaN MODFETs is an area of increasing interest to the USAF as these devices become developed and integrated in satellite-based systems Irradiation is also a valuable tool for analyzing the quantum-level characteristics and properties that are responsible for device operation AlxGa1-xN/GaN MODFETs were fabricated and irradiated at liquid nitrogen temperatures by 0,45-1,2MeV electrons up to doses of 6*1016 e/cm2. Following irradiation, low temperature I-V measurements were recorded providing dose-dependent measurements Temperature-dependent I-V measurements were also made during room temperature annealing following irradiation I-V measurements …

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Progress In Research For Biofuel Cell, Yue Bao, Xia-Qin Wu Feb 2004

Progress In Research For Biofuel Cell, Yue Bao, Xia-Qin Wu

Journal of Electrochemistry

In this article, research progresses of the biofuel cell in recent years were summarized. The operation principle and classification of the biofuel cells were described. The role of the mediator for promoting electron transfer in biofuel cells and the techniques for improving the electric properties of biofuel cells, such as output potential, were discussed with some attracting research instances. Finally, the choke points for research of biofuel cell were explored, and the application prospect of biofuel cells was forecasted.

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Comments On Hilbert Transform Based Signal Analysis, David G. Long Feb 2004

Comments On Hilbert Transform Based Signal Analysis, David G. Long

Faculty Publications

The use of the Hilbert transform for time/frequency analysis of signals is briefly considered. While the Hilbert transform is based on arbitrary continuous signals, most practical signals are digitially sampled and time-limited. To avoid aliasing in the sampling process the signals must also be bandlimited. It is argued that it is reasonable to consider such sampled signals as periodic (this is the basis of the Discrete Fourier Transform [DFT]) since any other interpretation is inconsistent. A simple derivation of the Hilbert transform for a sampled, periodic is then given. It is shown that the instantaneous frequency can be easily computed …

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Integrated Microbattery Charger For Autonomous Systems, Brian W. Lefevre Feb 2004

Integrated Microbattery Charger For Autonomous Systems, Brian W. Lefevre

Theses and Dissertations

This thesis presents a microbattery recharging circuit suitable for autonomous microsystems. The battery charger chosen for this design is a constant current battery charger. Two methods of regulating the constant-current are discussed. A published shunt regulator design is analyzed and is presented with enhancements to the design. A series regulator that controls the current to the battery with a switch is designed and fabricated in a 1.5µm CMOS process. The fabricated prototype occupies less than 2.20x2.20mm and is expected to dissipate less than 25µW of power. A discrete model of the integrated circuit is constructed and tested to demonstrate that …

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On The Implementation Of Swarmlinda? A Linda System Based On Swarm Intelligence (Extended Version), Ahmed Charles, Ronaldo Menezes, Robert Tolksdorf Feb 2004

On The Implementation Of Swarmlinda? A Linda System Based On Swarm Intelligence (Extended Version), Ahmed Charles, Ronaldo Menezes, Robert Tolksdorf

Electrical Engineering and Computer Science Faculty Publications

Natural-forming multi-agent systems (aka Swarms) can grow to enormous sizes and perform seemingly complex tasks without the existence of any centralized control. Their success comes from the fact that agents are simple and the interaction with the environment and neighboring agents is local in nature. In this paper we discuss the implementation of SwarmLinda, a Linda-based system that abstracts Linda concepts in terms of swarm intelligence constructs such as scents and stigmergy. The goal of this implementation is to achieve many characteristics such as scalability, adaptiveness and some level of fault tolerance. This paper describes our initial version of SwarmLinda …

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Ultra-Wide (Uwb) Communications: New Paradigms And Opportunities., Robert H. Morelos-Zaragoza Feb 2004

Ultra-Wide (Uwb) Communications: New Paradigms And Opportunities., Robert H. Morelos-Zaragoza

Faculty Publications

In this talk, the unique characteristics of ultra wideband (UWB) communications systems are introduced. Receiver design considerations are presented. Focus is on the relation between the symbol duration and the delay spread of the channel. This determines whether the receiver should use a Rake receiver (Spread-spectrum system) or an equalizer (multiple carrier or OFDM system).

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A "Divide And Conquer" Technique For Implementing Wide Dynamic Range Continuous-Time Filters, Yorgos Palaskas, Yannis Tsividis, Vladimir I. Prodanov, Vito Boccuzzi Feb 2004

A "Divide And Conquer" Technique For Implementing Wide Dynamic Range Continuous-Time Filters, Yorgos Palaskas, Yannis Tsividis, Vladimir I. Prodanov, Vito Boccuzzi

Electrical Engineering

This paper presents a technique for implementing analog filters with wide dynamic range and low power dissipation and chip area. The desired dynamic range of the filter is divided into subranges, each covered by a different filtering path optimized specifically for this subrange. This results in small admittance levels for the individual filtering paths and correspondingly small power dissipation and chip area. The system provides undisturbed output during range switching, contrary to conventional automatic gain control (AGC)/filter arrangements that generate disturbances every time the gain of the AGC changes. We also report on a low-noise highly linear CMOS transconductor useful …

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Laboratory Project In Wireless Fsk Receiver Design, Michael A. Jensen, Cynthia Fuse, Raymond Woodward Feb 2004

Laboratory Project In Wireless Fsk Receiver Design, Michael A. Jensen, Cynthia Fuse, Raymond Woodward

Faculty Publications

This paper describes a wireless local area network laboratory project that provides senior and first-year graduate students in microwave engineering courses the opportunity to design, build, and test several passive microstrip components and integrate them into a working system. Students design filters, couplers, amplifiers, diode detectors, quarter-wave transformers, antennas, and stub matching networks in weekly labs that parallel-lectures in a one-semester microwave engineering course. This paper also describes simple inexpensive prototyping and testing methods that have been used in this course. Laboratory materials and technical details of the design are provided on the web for students and educators.

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