Signal Processing Commons^™

Full-Wave Based Validation Of Stripline Field Applicator For Low Frequency Material Measurements, James H. Crane Ii

Theses and Dissertations

This research presents the analysis and verification of a stripline designed by Air Force Research Laboratory for use in measuring the electrical properties of materials at low frequencies and high temperature. It is designed to operate in the TEM mode up to 4 Ghz and have a characteristic impedance of 50 ohms. A full wave base method is used to analyze the structure. The parallel plate waveguide dyadic Green's function is developed for a current immersed in a PEC parallel plate environment. It is used to formulate a pair of coupled electric field integral equations (CIE). These CIEs are solved …

Blind Deconvolution Through Polarization Diversity Of Long Exposure Imagery, Steven P. James

Theses and Dissertations

The purpose of the algorithm developed in this thesis was to create a post processing method that could resolve objects at low signal levels using polarization diversity and no knowledge of the atmospheric seeing conditions. The process uses a two-channel system, one unpolarized image and one linearly polarized image, in a GEM algorithm to reconstruct the object. Previous work done by Strong showed that a two-channel system using polarization diversity on short exposure imagery could produce images up to twice the diffraction limit. In this research, long exposure images were simulated and a simple Kolmogorov model used. This allowed for …

Detecting Near-Earth Objects Using Cross-Correlation With A Point Spread Function, Anthony P. O'Dell

Theses and Dissertations

This thesis describes a process to help discover Near-Earth Objects (NEOs) of larger than 140 meters in diameter from ground based telescopes. The process involves using Nyquist sampling rate to take data from a ground-based telescope and measuring the atmospheric seeing parameter, r₀, at the time of data collection. r0 is then used to create a point spread function (PSF) for a NEO at the visual magnitude limit of the telescope and exposure time. This PSF is cross-correlated with the Nyquist sampling rate image from the telescope to reduce the noise and therefore increase the detection probability of …

Failure Detection Of A Pseudolite-Based Reference System Using Residual Monitoring, Michael A. Ciampa

Theses and Dissertations

The 746th TS uses a flight reference system referred to as the Central Inertial and GPS Test Facility (CIGTF) Reference System (CRS). Currently the CRS is the modern standard flight reference system for navigation testing, but high accuracy is dependent on the availability of GPS. A pseudolite system is currently being developed to augment the CRS and supply the capability to maintain high accuracy navigation under normal and jamming conditions. Pseudolite measurements typically contain cycle slips and other errors (such as multipath, tropospheric error, measurement noise) that can affect reliability. Past work relied on the receiver-reported signal-to-noise (SNR) value to …

Using Shadows To Detect Targets In Synthetic Aperture Radar Imagery, Brian P. Donnell

Theses and Dissertations

Synthetic Aperture Radar (SAR) can generate high resolution imagery of re- mote scenes by combining the phase information of multiple radar pulses along a given path. SAR based Intelligence, Surveillance, and Reconnaissance (ISR) has the advantage over optical ISR that it can provide usable imagery in adverse weather or nighttime conditions. Certain radar frequencies can even result in foliage or limited soil penetration, enabling imagery to be created of objects of interest that would otherwise be hidden from optical surveillance systems. This thesis demonstrates the capability of locating stationary targets of interest based on the locations of their shadows and …

Fusion Of Inertial Sensors And Orthogonal Frequency Division Multiplexed (Ofdm) Signals Of Opportunity For Unassisted Navigation, Jason G. Crosby

Theses and Dissertations

The advent of the global positioning system (GPS) has provided worldwide high-accuracy position measurements. However, GPS may be rendered unavailable by jamming, disruption of satellites, or simply by signal shadowing in urban environments. Thus, this thesis considers fusion of Inertial Navigation Systems (INS) and Orthogonal Frequency Division Multiplexed (OFDM) signals of opportunity (SOOP) for navigation. Typical signal of opportunity navigation involves the use of a reference receiver and uses time difference of arrival (TDOA) measurements. However, by exploiting the block structure of OFDM communication signals, the need for the reference receiver is reduced or possibly removed entirely. This research uses …

Radar Imaging With A Network Of Digital Noise Radar Systems, Ashley L. Schmitt

Theses and Dissertations

Today's battlefield consists of a blend of humans and machines working together to locate and monitor the enemy. Due to the threat of terrorism, today's enemy can be anyone and they can exist anywhere even in populated cities. Monitoring human activities in an urban environment is a difficult problem due to walls, clutter, and other obstructions. This thesis focused on developing a network of digital noise radar sensors that could operate simultaneously to track humans and non-human targets inside rooms and through walls. The theory, application, and results are discussed throughout this thesis. A noise radar works by cross correlating …

Abstracting Gis Layers From Hyperspectral Imagery, Torsten E. Howard

Theses and Dissertations

Modern warfare methods in the urban environment necessitates the use of multiple layers of sensors to manage the battle space. Hyperspectral imagers are one possible sensor modality to provide remotely sensed images that can be converted into Geographic Information Systems (GIS) layers. GIS layers abstract knowledge of roads, buildings, and scene content and contain shape files that outline and highlight scene features. Creating shape files is a labor-intensive and time-consuming process. The availability of shape files that reflect the current configuration of an area of interest significantly enhances Intelligence Preparation of the Battlespace (IPB). The solution presented in this thesis …

Utilizing Microelectromechanical Systems (Mems) Micro-Shutter Designs For Adaptive Coded Aperture Imaging (Acai) Technologies, Mary M. Ledet

Theses and Dissertations

The Air Force has long relied on surveillance for intelligence and strategic purposes. Most surveillance systems rely on a lensing system to acquire their images, most of which are in either the visible or infrared wavelengths. Because lensing systems can be expensive, obtrusive, or hard to maintain, researchers have designed adaptive coded aperture imaging (ACAI) as a replacement system. Coded aperture imaging (CAI) has been used in both the astronomical and medical communities for years due to its ability to image light at short wavelengths and thus replacing conventional lenses. Where CAI is limited, researchers have discovered that adaptive coded …

Evaluation Of Performance Of A Maximum Likelihood Estimator For Tracking Purposes In The Presence Of Speckle Noise, Adrian Brett Monz

Theses and Dissertations

In many cases, optical tracking systems do not have cooperative beacons avail- able. This is particularly true for the case involving tracking a laser illuminated target such as a missile seeker head, where the object of interest is an extended source. Furthermore the extended source is often observed in the presence of noise such as shot and speckle noise as well as atmospheric turbulence which further degrades the signal. This research effort presents the evaluation of an existing algorithm based on the maximum-likelihood technique for tilt estimation in the presence of extended sources and speckle noise, with particular application to …

Subjective Audio Quality Over A Secure Ieee 802.11n Draft 2.0 Wireless Local Area Network, Benjamin W. Ramsey

Theses and Dissertations

This thesis investigates the quality of audio generated by a G.711 codec and transmission over an IEEE 802.11n draft 2.0 wireless local area network (WLAN). Decline in audio quality due to additional calls or by securing the WLAN with transport mode Internet Protocol Security (IPsec) is quantified. Audio quality over an IEEE 802.11n draft 2.0 WLAN is also compared to that of IEEE 802.11b and IEEE 802.11g WLANs under the same conditions. Audio quality is evaluated by following International Telecommunication Union Telecommunication Standardization Sector (ITU-T) Recommendation P.800, where human subjects rate audio clips recorded during various WLAN configurations. The Mean …

Localization Quality Assessment In Source Separation-Based Upmixing Algorithms, Dan Barry, Gavin Kearney

Conference papers

In this paper we explore the source localisation accuracy and perceived spatial distortion of a source separation based upmix algorithm for 2 to 5 channel conversion. Unlike traditional upmixing techniques, source separation based techniques allow individual sources to be separated from the mixture and repositioned independently within the surround sound field. Generally, spectral artefacts and source interference generated during the source separation process are masked when the upmixed sound field is presented in its entirety; however, this can lead to perceived spatial distortion and ambiguous source localisation. Here, we use subjective testing to compare the localisation perceived on a purposely …

Automatic Musical Meter Detection, Mikel Gainza

Conference papers

A method that automatically estimates the metrical structure of a piece of music is presented. The approach is based on the generation of a beat similarity matrix, which provided information about the similarity between any two beats of a piece of music. The repetitive structure of most music is exploited by processing the beat similarity matrix in order to identify similar patterns of beats in different parts of a piece. This principles proves to be equally effective for the detection of both duple and triple meters as awll as complex meters. The use of beat positions and dynamic programming techniques …

Structural Segmentation Of Irish Traditional Music Using Chroma At Set Accented Tone Locations, Cillian Kelly, Mikel Gainza, David Dorran, Eugene Coyle

Conference papers

An approach is presented which provides a structural segmentation of Irish Traditional Music. Chroma information is extracted at certain locations within the music. The resulting chroma vectors are compared to determine similar structural segments. Chroma is only calculated at "set accented tone" locatins within the music. "Set accented tones" are considered to be impervious to melodic variation and are entirely representative of an Irish Traditional tune. Results show that comparing "set accented tones" represented by chroma significantly increases the structural segmentation accuracy that when "set accented tones" are represented by pitch values.

Three-Dimensional Target Modeling With Synthetic Aperture Radar, John R. Hupton

Master's Theses

Conventional Synthetic Aperture Radar (SAR) offers high-resolution imaging of a target region in the range and cross-range dimensions along the ground plane. Little or no data is available in the range-altitude dimension, however, and target functions and models are limited to two-dimensional images. This thesis first investigates some existing methods for the computation of target reflectivity data in the deficient elevation domain, and a new method is then proposed for three-dimensional (3-D) SAR target feature extraction.

Simulations are implemented to test the decoupled least-squares technique for high-resolution spectral estimation of target reflectivity, and the accuracy of the technique is assessed. …

Information Hiding By Stochastic Disfusion And Its Application To Printed Document Authentication, Jonathan Blackledge, Eugene Coyle

Conference papers

The use of image based information exchange has grown rapidly over the years in terms of both e-to-e image storage and transmission and in terms of maintaining paper documents in electronic form. Further, with the dramatic improvements in the quality of COTS (Commercial-O-The-Shelf) printing and scanning devices, the ability to counterfeit electronic and printed documents has become a widespread problem. Consequently, there has been an increasing demand to develop digital watermarking, information hiding and covert encryption methods which can be applied to both electronic and printed images (and documents) for the purposes of authentication, prevent unauthorized copying and, in the …

A Mobile Ecg Monitoring System With Context Collection, Jin Peng Li, Damon Berry, Richard Hayes

Conference Papers

Preventative health management represents a shift from the traditional approach of reactive treatment-based healthcare towards a proactive wellness-management approach where patients are encouraged to stay healthy with expert support when they need it, at any location and any time. This work represents a step along the road towards proactive, preventative healthcare for cardiac patients. It seeks to develop a smart mobile ECG monitoring system that requests and records context information about what is happening around the subject when an arrhythmia event occurs. Context information about the subject’s activities of daily living will, it is hoped, provide an enriched data set …

Inverse Scattering Solutions With Applications To Electromagnetic Signal Processing, Jonathan Blackledge, Timo Hamalainen, Jyrki Joutsensalo

Articles

When a signal is recorded that has been physically generated by some scattering process (the interaction of electromagnetic, acoustic or elastic waves with inhomogeneous materials, for example), the ‘standard model’ for the signal (i.e. information content convolved with a characteristic Impulse Response Function) is usually based on a single scattering approximation. An additive noise term is introduced into the model to take into account a range of non-deterministic factors including multiple scattering that, along with electronic noise and other background noise sources, is assumed to be relatively weak. Thus, the standard model is based on a ‘weak field condition’ and …

On The Use Of The Beta Divergence For Musical Source Separation, Derry Fitzgerald, Matt Cranitch, Eugene Coyle

Conference papers

Non-negative Tensor Factorisation based methods have found use in the context of musical sound source separation. These techniques require the use of a suitable cost function to determine the optimal factorisation, and most work has focused on the use of the generalised Kullback-Liebler divergence, and more recently the Itakura-Saito divergence. These divergences can be regarded as limiting cases of the parameterised Beta divergence. This paper looks at the use of the Beta Divergence in the context of musical source separation with a view to determining an optimal value of Beta for this problem. This is considered for both magnitude and …

Musical Sound Source Separation Using Extended Tensor Decompositions, Derry Fitzgerald

Conference papers

Recently, tensor decompositions have found use in sound source separation. In particular, non-negative tensor decompositions have received a lot of attention due to their ability to decompose audio spectrograms into meaningful ”parts” such as individual notes. Extensions to the basic non-negative tensor factorisation framework allow the incorporation of additional constraints, such as shift-invariance in both frequency and time. This enables the factorisations to capture more complex structures than individual notes, such as individual sources playing different pitches and time-evolving instrument timbres. Further music specific constraints such as harmonicity and source-filter modeling have been shown to improve separation performance for musical …

Using Tensor Factorisation Models To Separate Drums From Polyphonic Music, Derry Fitzgerald, Matt Cranitch, Eugene Coyle

Conference papers

This paper describes the use of Non-negative Tensor Factorisation models for the separation of drums from polyphonic audio. Improved separation of the drums is achieved through the incorporation of Gamma Chain priors into the Non-negative Tensor Factorisation framework. In contrast to many previous approaches, the method used in this paper requires little or no pre-training or use of drum templates. The utility of the technique is shown on real-world audio examples.

Imaging Reconstruction For Light Scattering From A Tenuous Random Medium, Jonathan Blackledge

Conference papers

We consider the basis for describing strong scattering in terms of diffusive processes based on the diffusion equation. Intermediate strength scattering is then considered in terms of a fractional diffusion equation which is studied using results from fractional calculus. This approach is justified in terms of the generalization of a random walk model with no statistical bias in the phase to a random walk that has a phase bias and is thus, only `partially' or `fractionally' diffusive. A Green's function solution to the fractional diffusion equation is studied and a result derived that provides a model for an incoherent image …

Optimal Design Of Discrete-Time Delta Sigma Modulators, Matthew Edward Jackson

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis, optimal signal transfer functions (STFs) and noise transfer functions (NTFs) for discrete time delta sigma (ΔΣ) modulators are determined. For a given oversampling rate (OSR), these STFs and NTFs are optimized with respect to a weighted combination of the ΔΣ modulator's signal-to-noise ratio (SNR) and dynamic range (DR). This optimization problem is solved using a novel hybrid orthogonal genetic (HOG) algorithm that uses customized genetic operators to improve algorithm performance and accuracy when applied to multimodal, non-differentiable performance surfaces. To generate optimal system functions, the HOG algorithm is implemented as a constrained global optimizer to minimize cost …

Free Regions Of Sensor Nodes, Laxmi P. Gewali, Navin Rongatana, Henry Selvaraj, Jan B. Pedersen

Electrical & Computer Engineering Faculty Research

We introduce the notion of free region of a node in a sensor network. Intuitively, a free region of a node is the connected set of points R in its neighborhood such that the connectivity of the network remains the same when the node is moved to any point in R. We characterize several properties of free regions and develop an efficient algorithm for computing them. We capture free region in terms of related notions called in-free region and out-free region. We present an O(n2) algorithm for constructing the free region of a node, where n is the number of …