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Articles 31 - 48 of 48
Full-Text Articles in Signal Processing
Evaluating The Correlation Characteristics Of Arbitrary Am And Fm Radio Signals For The Purpose Of Navigation, Bryan S. Kim
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 …
Side-Looking Airborne Adaptive Operation In Hot Clutter, Timothy W. Lawson
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
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 …
Non-Cooperative Detection Of Frequency-Hopped Gmsk Signals, Clint R. Sikes
Non-Cooperative Detection Of Frequency-Hopped Gmsk Signals, Clint R. Sikes
Theses and Dissertations
Many current and emerging communication signals use Gaussian Minimum Shift Keyed (GMSK), Frequency-Hopped (FH) waveforms to reduce adjacent-channel interference while maintaining Low Probability of Intercept (LPI) characteristics. These waveforms appear in both military (Tactical Targeting Networking Technology, or TTNT) and civilian (Bluetooth) applications. This research develops wideband and channelized radiometer intercept receiver models to detect a GMSK-FH signal under a variety of conditions in a tactical communications environment. The signal of interest (SOI) and receivers have both fixed and variable parameters. Jamming is also introduced into the system to serve as an environmental parameter. These parameters are adjusted to examine …
Supplementing An Ad-Hoc Wireless Network Routing Protocol With Radio Frequency Identification (Rfid) Tags, Leroy S. Willemsen
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 …
Nonlinear Suppression Of Range-Ambiguous Clutter For Outdoor Radar Measurement Facilities, Michael C. Baumgartner
Nonlinear Suppression Of Range-Ambiguous Clutter For Outdoor Radar Measurement Facilities, Michael C. Baumgartner
Theses and Dissertations
In the outdoor measurement facility, a certain amount of real estate is owned by the organization, and therefore can be groomed to keep clutter contributions to a minimum. As the transmit signal travels further down range, however, returns from long-range clutter sources are inevitable and can have a significant impact on measurement accuracy. This research effort investigates the effectiveness of employing nonlinear suppression (NLS) to abate long-range ambiguous clutter in these facilities. Initial testing provides an extended proof-of-concept for coincident point scatterers representing target and clutter sources. The NLS process is finally applied to simulated measured data from the National …
Multiframe Shift Estimation, Stephen A. Bruckart
Multiframe Shift Estimation, Stephen A. Bruckart
Theses and Dissertations
The purpose of this research was to develop a fundamental framework for a new approach to multiframe translational shift estimation in image processing. This thesis sought to create a new multiframe shift estimator, to theoretically prove and experimentally test key properties of it, and to quantify its performance according to several metrics. The new estimator was modeled successfully and was proven to be an unbiased estimator under certain common image noise conditions. Furthermore its performance was shown to be superior to the cross correlation shift estimator, a robust estimator widely used in similar image processing cases, according to several criteria. …
Space-Time Adaptive Processing For Side-Looking Arrays With Platform Maneuver, John T. Buckreis
Space-Time Adaptive Processing For Side-Looking Arrays With Platform Maneuver, John T. Buckreis
Theses and Dissertations
This research effort develops a space-time adaptive processing (STAP) radar data model for the side-looking (SL) array with platform maneuver. A primary assumption of most STAP models is the absence of platform maneuver during the coherent processing interval (CPI). This research abandons the platform stationarity assumption, allowing platform pitch, roll, and yaw during the CPI. The model developed characterizes platform maneuver effects on the clutter spectrum, examines Matched Filter (MF) output Signal-to-Interference-plus-Noise-Ratio (SINR), and investigates maneuver impact on sample support homogeneity. The introduction of pitch marginally impacts MF SINR due to the lack of achieved azimuth resolution in this research, …
Image Processing Resource Allocation Methods For Multi-Target Tracking Of Dismounted Targets In Urban Environments, Jonathan P. Champion
Image Processing Resource Allocation Methods For Multi-Target Tracking Of Dismounted Targets In Urban Environments, Jonathan P. Champion
Theses and Dissertations
Dismounted targets can be tracked in urban environments with video sensors. Real-time systems are unable to process all of the imagery, demanding some method for prioritization of the processing resources. Furthermore, various segmentation algorithms exist within image processing, each algorithm possesses unique capabilities, and each algorithm has an associated computational cost. Additional complexity arises in the prioritization problem when targets become occluded (e.g., by a building) and when the targets are intermixed with other dismounted entities. This added complexity leads to the question "which portions of the scene warrant both low cost and high cost processing?" The approach presented in …
Passive Ranging Using Atmospheric Oxygen Absorption Spectra, Michael R. Hawks
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
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 …
Digital Signal Processing (Second Edition), Jonathan Blackledge
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
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
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
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
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
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