Engineering Commons^™

Passive Ranging Using Atmospheric Oxygen Absorption Spectra, Michael R. Hawks

Theses and Dissertations

The depth of absorption bands in observed spectra of distant, bright sources can be used to estimate range to the source. A novel approach is presented and demonstrated using observations of the oxygen absorption band near 762 nm. Range is estimated by comparing observed values of band-average absorption against curves derived from either historical data or model predictions. Curves are based on fitting a random band model to the data, which reduces average range error by 67% compared to the Beer's Law model used in previous work. A new modification to existing band models for long, inhomogeneous paths is presented …

A Climatological Study Of Equatorial Gps Data And The Effects On Ionospheric Scintillation, Katharine A. Wicker

Theses and Dissertations

Ionospheric scintillation is detrimental to radio signals, especially those from the global positioning system. Such scintillation is caused when a signal permeates the ionosphere through plasma bubbles. The signal’s phase and amplitude can be altered, and a receiver on the ground can lose lock on the GPS signal. Measured using a zero to one index known as S4, scintillation severity is based upon season, solar cycle, time of day, location and frequency. The most severe scintillation occurs at the equatorial anomaly, or fifteen degrees north and south of the equator. Seven years of data from fifteen different locations around the …

Forward-Looking Radar Clutter Suppression Using Frequency Diverse Arrays, Piotr Baizert

Theses and Dissertations

This thesis introduces a new array structure, the Frequency Diverse Array (FDA), where each channel transmits and receives at a different frequency. The resulting range-dependent FDA antenna pattern is proposed to improve forward-looking clutter suppression. The planar FDA radar data model is derived and analytically verified to be equivalent to the constant frequency data model when each element frequency is set to the same value. The linear FDA at high platform altitude provides significant benefits? by reducing the range ambiguous clutter contribution, improving target detection by up to 10 dB. At low altitudes without range ambiguous clutter the linear FDA …

Evaluating The Correlation Characteristics Of Arbitrary Am And Fm Radio Signals For The Purpose Of Navigation, Bryan S. Kim

Theses and Dissertations

The Global Positioning System (GPS) provides position estimates on the Earth at anytime, anywhere and in any weather. However, to provide robust positioning, GPS requires an unobstructed path to satellite signals. As such, GPS performance generally degrades or becomes non-existent in environments such as large urban areas. This research investigates and analyzes the correlation characteristics of arbitrary AM and FM radio signals for the purpose of navigation. Simulations are conducted with different combinations of correlation methods (`fixed' or `varying'), modulation types (AM or FM), and signal types (song or voice). Out of the eight different variations considered, only two provided …

Multiple Model Methods For Cost Function Based Multiple Hypothesis Trackers, Matthew C. Kozak

Theses and Dissertations

Multiple hypothesis trackers (MHTs) are widely accepted as the best means of tracking targets in clutter. This research seeks to incorporate multiple model Kalman filters into an Integral Square Error (ISE) cost-function-based MHT to increase the fidelity of target state estimation. Results indicate that the proposed multiple model methods can properly identify the maneuver mode of a target in dense clutter and ensure that an appropriately tuned filter is used. During benign portions of flight, this causes significant reductions in position and velocity RMS errors compared to a single-filter MHT. During portions of flight when the mixture mean deviates significantly …

Decision Directed And Constant Modulus Algorithms Derived And Evaluated For Multicarrier Systems, Nicholas L. Linnenkamp

Theses and Dissertations

The purpose of this research is to derive and examine blind adaptive algorithms for equalizing multicarrier (MC) communication systems. The author analyzes how they perform under varying environmental conditions and parametric variations, focusing on equalizers set in cascade with the channel. Two well-accepted and widely known cost functions, Decision Directed (DD) and Constant Modulus (CM), are applied to the MC signal structure, and gradient descent algorithms based on both DD and CM functions are derived, analyzed, and compared. Comparison of the new algorithms, Multi-Carrier Decision Directed (MCDD) and Multi-Carrier Constant Modulus (MCCM), focuses on detailing how each algorithm performs when …

Side-Looking Airborne Adaptive Operation In Hot Clutter, Timothy W. Lawson

Theses and Dissertations

This research effort examines side-looking airborne radar operation in hot clutter. In this context, hot clutter is an electronic counter-measure used to degrade airborne radar performance. Hot clutter occurs by illuminating the ground with an airborne jammer at some velocity, azimuth, elevation, and range from the airborne radar. This research uses a simplifying assumption where the bistatic hot clutter radar cross section (RCS) scattering statistics are identical to the monostatic clutter RCS scattering statistics. When the airborne jammer waveform scattered returns are perfectly coherent with the radar waveform, the radar cannot distinguish between the returns transmitted by the jammer and …

Wideband Signal Detection Using A Down-Converting Channelized Receiver, Willie H. Mims

Theses and Dissertations

Ultra wideband (UWB) signals typically occupy a very large spectral bandwidth resulting from extremely short duration pulses. Direct sequence spread spectrum (DSSS) signals typically occupy a large spectral bandwidth resulting from spreading methods. Both signals can be difficult to detect without having prior knowledge of their structure and/or existence. This research develops and evaluates techniques for the non-cooperative (non-matched filter) detection of such signals. Impulse-like UWB and DSSS signals are received in an Additive White Gaussian Noise (AWGN) channel and are assessed using a bandpass filtered, down-converting (BPF-D/C) channelized receiver architecture. Modeling and simulation are conducted to characterize BPF-D/C channelized …

Characterization And Design Of High-Level Vhdl I/Q Frequency Downconverter Via Special Sampling Scheme, Jesse P. Somann

Theses and Dissertations

This study explores the characterization and implementation of a Special Sampling Scheme (SSS) for In-Phase and Quad-Phase (I/Q) down conversion utilizing top-level, portable design strategies. The SSS is an under-developed signal sampling methodology that can be used with military and industry receiver systems, specifically, United States Air Force (USAF) video receiver systems. The SSS processes a digital input signal-stream sampled at a specified sampling frequency, and down converts it into In-Phase (I) and Quad-Phase (Q) output signal-streams. Using the theory and application of the SSS, there are three main objectives that will be accomplished: characterization of the effects of input, …

Supplementing An Ad-Hoc Wireless Network Routing Protocol With Radio Frequency Identification (Rfid) Tags, Leroy S. Willemsen

Theses and Dissertations

Wireless sensor networks (WSNs) have a broad and varied range of applications, yet all of these are limited by the resources available to the sensor nodes that make up the WSN. The most significant resource is energy. A WSN may be deployed to an inhospitable or unreachable area, leaving it with a non-replenishable power source. This research examines a way of reducing energy consumption by augmenting the nodes with radio frequency identification (RFID) tags that contain routing information. It was expected that RFID tags would reduce the network throughput, the ad hoc on-demand distance vector (AODV) routing traffic sent, and …

Verification Of A Decision Level Fusion Algorithm Using A Proven Atr System And Measured Sar Data, James Douglas Thompson

Theses and Dissertations

Decision level fusion (DLF) algorithms combine outputs of multiple single sensors to make one confident declaration of a target. This research compares performance results of a DLF algorithm using measured data and a proven ATR system with results from simulated data and a modeled ATR system. This comparison indicates that DLF offers significant performance improvements over single sensor looks. However, results based on simulated data and a modeled ATR are slightly optimistic and overestimate results from measured data and a proven ATR system by nearly 10% over all targets tested.

Digital Signal Processing (Second Edition), Jonathan Blackledge

Books/Book chapters

This book provides an account of the mathematical background, computational methods and software engineering associated with digital signal processing. The aim has been to provide the reader with the mathematical methods required for signal analysis which are then used to develop models and algorithms for processing digital signals and finally to encourage the reader to design software solutions for Digital Signal Processing (DSP). In this way, the reader is invited to develop a small DSP library that can then be expanded further with a focus on his/her research interests and applications.

There are of course many excellent books and software …

Nist Sre Speaker Recognition Evaluation Workshop 2006, Sanjay Patil, Vinod Prakash, Pongtep Angkitatrakul, John Hansen, Wooil Kim, Syed Moosa

Sanjay A. Patil

No abstract provided.

Radio Frequency Enabled Soil Redox Potential Sensor Networks, Chris Holme

Theses : Honours

There is a need for' cost effective tools and data collection methods for field measurements; to increase both productivity and volumes of collected data in the quest for enhanced understanding and management of environmental systems. To such end, various technologies that may be combined into a cost effective soil redox sensor network were explored. Suitability of each technology, as a component of said network was evaluated. A prototype soil redox sensor network was constructed and basic laboratory and field testing was completed. Results indicate that the prototype sensor network functions correctly within bounds. Both laboratory and field testing show that …

An Enhancement Of Decimation Process Using Fast Cascaded Integrator Comb (Cic), Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.

An Overview Of The Decimation Process And Its Vlsi Implementation, Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.

An Improved Recursive And Non-Recursive Comb Filter For Dsp Applications, Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.

Vlsi Implementation Of Cascaded Integrator Comb Filters For Dsp Applications, Rozita Teymourzadeh, Masuri Othman

Dr. Rozita Teymourzadeh, CEng.