Signal Processing Commons^™

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 …

Forward Looking Radar: Interference Modelling, Characterization, And Suppression, James T. Caldwell

Theses and Dissertations

This research characterizes forward looking radar performance while noting differences with traditionally examined sidelooking radar. The target detection problem for forward looking radar is extremely difficult due to the severe, heterogeneous and range dependent ground clutter. Consequently, forward looking radar detection represents an important but overlooked topic because of the increased difficulty compared to sidelooking radar. This void must be filled since most fighter aircraft use forward looking radar, making this topic intensely interesting to the Air Force. After characterizing forward looking radar performance, basic radar concepts along with advanced adaptive interference suppression techniques improve the output Signal-to-Interference-plus-Noise Ratio (SINR) …

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 …

Characterization Of The Target-Mount Interaction In Radar Cross Section Measurement Calibrations, Donald W. Powers

Theses and Dissertations

Radar Cross Section (RCS) measurements are quintessential in understanding target scattering phenomenon. The reduced RCS of modern weapons systems stresses the capability of current RCS measurement ranges. A limiting factor that has recently become more significant is the electromagnetic coupling between a test target and the mounting hardware used to support it and control its orientation during the RCS measurement. Equally important is the electromagnetic coupling between the RCS calibration artifact and its mount, which provides an opportunity to explore the coupling phenomena without delving into operationally sensitive areas. The primary research goal was to characterize the interaction between a …

A Fast And Simple Algorithm For Computing M-Shortest Paths In State Graph, M. Sherwood, Laxmi P. Gewali, Henry Selvaraj, Venkatesan Muthukumar

Electrical & Computer Engineering Faculty Research

We consider the problem of computing m shortest paths between a source node s and a target node t in a stage graph. Polynomial time algorithms known to solve this problem use complicated data structures. This paper proposes a very simple algorithm for computing all m shortest paths in a stage graph efficiently. The proposed algorithm does not use any complicated data structure and can be implemented in a straightforward way by using only array data structure. This problem appears as a sub-problem for planning risk reduced multiple k-legged trajectories for aerial vehicles.

A Computer-Based Articulation Training Aid For Short Words (Cata), Mukund Devarajan

Electrical & Computer Engineering Theses & Dissertations

Several improvements in the vowel articulation training aid (VATA) are described, as well as the efforts to extend the visual feedback system to operate with short words in the form of consonant, vowel and consonant (CVC). The extended version of the visual feedback system is referred to as CATA (Computer-based Articulation Training Aid); the vowel version of the aid (VATA) only operates with ten American English monopthong vowels. Improvements in VATA include the use of a neural network (NN) recognizer method to prune a large database of vowel recordings to eliminate noisy and/or mispronounced tokens. The spectral jitter problem, previously …

Automatic Classification Of African Elephant (Loxodonta Africana) Follicular And Luteal Rumbles, Michael T. Johnson, Patrick J. Clemins

Dr. Dolittle Project: A Framework for Classification and Understanding of Animal Vocalizations

Recent research in African elephant vocalizations has shown that there is evidence for acoustic differences in the rumbles of females based on the phase of their estrous cycle (1). One reason for these differences might be to attract a male for reproductive purposes. Since rumbles have a fundamental frequency near 10Hz, they attenuate slowly and can be heard over a distance of several kilometers. This research exploits differences in the rumbles to create an automatic classification system that can determine whether a female rumble was made during the luteal or follicular phase of the ovulatory cycle. This system could be …

Implementing An Integrated Signaling And Power Distribution Control System For Remotely Located Devices, Andrew Stephen Hintz

Graduate Theses - Electrical and Computer Engineering

A system was designed and implemented that combined the distribution of high-current power with a digital control signal over a common conductor. Two different versions of this system were implemented. Initially, a design based on of commercially available parts was created and tested to prove that the concept of combining communications and power is valid. The resulting design was then miniaturized to show that the system might be combined onto a single integrated circuit. In the miniaturization process, some circuit blocks were redesigned to take advantage of the flexibility provided by ASIC designs. Both the proof of concept and the …

Classification Of Radar Targets Using Invariant Features, Gregory J. Meyer

Theses and Dissertations

Automatic target recognition ATR using radar commonly relies on modeling a target as a collection of point scattering centers, Features extracted from these scattering centers for input to a target classifier may be constructed that are invariant to translation and rotation, i.e., they are independent of the position and aspect angle of the target in the radar scene. Here an iterative approach for building effective scattering center models is developed, and the shape space of these models is investigated. Experimental results are obtained for three-dimensional scattering centers compressed to nineteen-dimensional feature sets, each consisting of the singular values of the …

Application Of Speech Recognition To African Elephant (Loxodonta Africana) Vocalizations, Patrick J. Clemins, Michael T. Johnson

Dr. Dolittle Project: A Framework for Classification and Understanding of Animal Vocalizations

This paper presents a novel application of speech processing research, classification of African elephant vocalizations. Speaker identification and call classification experiments are performed on data collected from captive African elephants in a naturalistic environment. The features used for classification are 12 mel-frequency cepstral coefficients plus log energy computed using a shifted filter bank to emphasize the infrasound range of the frequency spectrum used by African elephants. Initial classification accuracies of 83.8% for call classification and 88.1% for speaker identification were obtained. The long-term goal of this research is to develop a universal analysis framework and robust feature set for animal …

Redundant Discrete Wavelet Transform Based Super-Resolution Using Sub-Pixel Image Registration, Daniel L. Ward

Theses and Dissertations

The limited resolution of video imagery taken by aircraft, over geographical areas of interest, hinders the accurate extraction of useful information. The frame resolution of the video is determined by the camera that created it. Information exists about the camera which can be used to increase frame resolution beyond the resolution capability of the camera. This is achieved by a process called super-resolution, which uses multiple low-resolution video frames to create one high-resolution image.

Evaluating The Performance Of Multiple Classifier Systems: A Matrix Algebra Representation Of Boolean Fusion Rules, Justin M. Hill

Theses and Dissertations

Given a finite collection of classifiers one might wish to combine, or fuse, the classifiers in hopes that the multiple classifier system (MCS) will perform better than the individuals. One method of fusing classifiers is to combine their final decision using Boolean rules (e.g., a logical OR, AND, or a majority vote of the classifiers in the system). An established method for evaluating a classifier is measuring some aspect of its Receiver Operating Characteristic (ROC) curve, which graphs the trade-off between the conditional probabilities of detection and false alarm. This work presents a unique method of estimating the performance of …

Feature Guided Image Registration Applied To Phase And Wavelet-Base Optic Flow, Kate R. Duffy

Theses and Dissertations

Optic Flow algorithms are useful in problems such as computers vision, navigational systems, and robotics. However, current algorithms are computationally expensive or lack the accuracy to be effective compared with traditionally navigation systems. Recently, lower accuracy inertial navigation systems (INS) based on Microelectromechanical systems (MEMS) technology have been proposed to replace more accurate traditional navigation systems.

Theoretical Analysis Of Information Watermarking In Wavelet-Based Video Compression, Brendan K. Casey

Theses and Dissertations

Embedding audio bits into images for transmission of video data alleviates the synchronization problem common in video transmission techniques. We continue work combining audio or other information bits and images into one file using digital watermarking techniques to correct the synchronization problem. The system compresses the file by using wavelet image coefficients and implementing bit plane coding. Our research encompasses incorporating five free variables into the watermark/compression technique. These variables are watermark robustness, number of coding iterations, number of image coefficients, number of watermarked information bits, and number of watermarked error correcting bits. By altering these variables, four measurements of …

Fast Compression Of Imagery With High Frequency Content, D. Scott Anderson

Theses and Dissertations

Image compression is an active area due to the many applications involving electronic media. Much research has been focused on image quality versus bit rate and/or algorithm speed. Here, we seek an effective image coder with a weighted constraint on speed. However, the compression must not taint the quality of impulsive features on the image. Moreover, the camera is operated in a mode that creates a dominant fixed pattern noise across the image array, degrading visual quality and disrupting compression performance. We propose a method that efficiently compresses such an image. We begin by characterizing and removing the fixed pattern …

Inquisitive Pattern Recognition, Amy L. Magnus

Theses and Dissertations

The Department of Defense and the Department of the Air Force have funded automatic target recognition for several decades with varied success. The foundation of automatic target recognition is based upon pattern recognition. In this work, we present new pattern recognition concepts specifically in the area of classification and propose new techniques that will allow one to determine when a classifier is being arrogant. Clearly arrogance in classification is an undesirable attribute. A human is being arrogant when their expressed conviction in a decision overstates their actual experience in making similar decisions. Likewise given an input feature vector, we say …

Digital Image Processing, Russell C. Hardie, Majeed M. Hayat

Electrical and Computer Engineering Faculty Publications

In recent years, digital images and digital image processing have become part of everyday life. This growth has been primarily fueled by advances in digital computers and the advent and growth of the Internet. Furthermore, commercially available digital cameras, scanners, and other equipment for acquiring, storing, and displaying digital imagery have become very inexpensive and increasingly powerful. An excellent treatment of digital images and digital image processing can be found in Ref. [1]. A digital image is simply a two-dimensional array of finite-precision numerical values called picture elements (or pixels). Thus a digital image is a spatially discrete (or discrete-space) …

Drum Transcription In The Presence Of Pitched Instruments Using Prior Subspace Analysis, Derry Fitzgerald, Robert Lawlor, Eugene Coyle

Conference papers

This paper demonstrates the use of Prior Subspace Analysis (PSA) as a method for transcribing drums in the presence of pitched instruments. PSA uses prior subspaces that represent the sources to be transcribed to overcome some of the problems associated with other subspace methods such as Independent Subspace Analysis (ISA) or sub-band ISA. The use of prior knowledge results in improved robustness for transcription purposes and enables the method to work more readily in the presence of pitched instruments than other subspace methods. The system presented in this paper attempts to extend the use of PSA to transcribe drum sounds …

Device Structure Effects On Electrical Crosstalk In Backwall Illuminated Cmos Compatible Photodiode Arrays, Paul Vernon Jansz

Theses : Honours

This research has made a comparative investigated of crosstalk in backside illuminated and frontside illuminated single junction photodiode and vertical double junction photodiode CMOS compatible pixels, using a commercial 2D device simulation package, SEMICAD DEVICE (1994). Comparison of pixel total, electron and hole quantum efficiency response and Absorption Volume data is undertaken. This is so that the underlying carrier drift-diffusion dynamics responsible for optimal pixel response resolution may be qualitatively understood, allowing prediction of even more optimal photodiode pixel configurations. The effect of varying the double junction and single junction photodiode pixel's geometry on response resolution is considered. Only for …

System Identification Using Higher Order Spectra, Aidan O'Dwyer

Conference papers

This communication will explore the use of particular types of frequency domain concepts, labelled higher order spectra, to help determine the frequency response of a process. This will allow the identification of the parameters of a single input, single output (SISO) model for a process (which includes a time delay), in both open loop and closed loop environments.

Evaluation Of Distributed Effects In Field Effect Transistors For High Frequency Applications, Srinivas Rowjee Cuddapah

Electrical & Computer Engineering Theses & Dissertations

Metal Semiconductor Field Effect Transistors are at the heart of currently used microwave and millimeter-wave devices. CAD (Computer Aided Design) models for MESFET are used in the development and optimization of high-speed microwave devices. The increase in the chip density demands more accurate models. A distributed small signal model was developed for a GaAs MESFET account of the high frequency effects.

The lumped model of the MESFET is inadequate at frequencies where the wavelength of operation approaches device dimensions. This is because different regions in the device can experience different amplitudes and phases of the biasing signal. In this thesis, …

Yet Another Algorithm For Pitch Tracking (Yaapt), Kavita Kasi

Electrical & Computer Engineering Theses & Dissertations

This thesis presents a pitch detection algorithm that is extremely robust for both high quality and telephone speech. The kernel method for this algorithm is the Normalized Cross Correlation (NCCF) reported by David Talkin [16]. Major innovations include: processing of the original acoustic signal and a nonlinearly processed version of the signal to partially restore very weak F0 components; intelligent peak picking to select multiple F0 candidates and assign merit factors; and, incorporation of highly robust pitch contours obtained from smoothed versions of low frequency portions of spectrograms. Dynamic programming is used to find the ''best" pitch track among all …

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 …

Automatic Target Recognition Classification System Evaluation Methodology, Christopher Brian Bassham

Theses and Dissertations

This dissertation research makes contributions towards the evaluation of developing Automatic Target Recognition (ATR) technologies through the application of decision analysis (DA) techniques. ATR technology development decisions should rely not only on the measures of performance (MOPs) associated with a given ATR classification system (CS), but also on the expected measures of effectiveness (MOEs). The purpose of this research is to improve the decision-makers in the ATR Technology development. A decision analysis framework that allows decision-makers in the ATR community to synthesize the performance measures, costs, and characteristics of each ATR system with the preferences and values of both the …

Autoassociative-Heteroassociative Neural Network, Claudia V. Kropas-Hughes, Steven K. Rogers, Mark E. Oxley, Matthew Kabrisky

AFIT Patents

An efficient neural network computing technique capable of synthesizing two sets of output signal data from a single input signal data set. The method and device of the invention involves a unique integration of autoassociative and heteroassociative neural network mappings, the autoassociative neural network mapping enabling a quality metric for assessing the generalization or prediction accuracy of the heteroassociative neural network mapping.

Implementation Of Large Neural Networks Using Decomposition, Henry Selvaraj, H. Niewiadomski, P. Buciak, M. Pleban, Piotr Sapiecha, Tadeusz Luba, Venkatesan Muthukumar

Electrical & Computer Engineering Faculty Research

The article presents methods of dealing with huge data in the domain of neural networks. The decomposition of neural networks is introduced and its efficiency is proved by the authors’ experiments. The examinations of the effectiveness of argument reduction in the above filed, are presented. Authors indicate, that decomposition is capable of reducing the size and the complexity of the learned data, and thus it makes the learning process faster or, while dealing with large data, possible. According to the authors experiments, in some cases, argument reduction, makes the learning process harder.

Airborne Radar Interference Suppression Using Adaptive Three-Dimensional Techniques, Todd B. Hale

Theses and Dissertations

This research advances adaptive interference suppression techniques for airborne radar, addressing the problem of target detection within severe interference environments characterized by high ground clutter levels, levels, noise jammer infiltration, and strong discrete interferers. Two-dimensional (2D) Space-Time Adaptive Processing (STAP) concepts are extended into three-dimensions (3D) by casting each major 2D STAP research area into a 3D framework. The work first develops an appropriate 3D data model with provisions for range ambiguous clutter returns. Adaptive 3D development begins with two factored approaches, 3D Factored Time-Space (3D-FTS) and Elevation-Joint Domain Localized (Elev-JDL). The 3D adaptive development continues with optimal techniques, i.e., …

An Analysis Of Mutually Dispersive Brown Symbols For Non-Linear Ambiguity Suppression, Matthew J. Papaphotis

Theses and Dissertations

This thesis significantly advances research towards the implementation of optimal Non-linear Ambiguity Suppression (NLS) waveforms by analyzing the Brown theorem. The Brown theorem is reintroduced with the use of simplified linear algebraic notation. A methodology for Brown symbol design and digitization is provided, and the concept of dispersive gain is introduced. Numerical methods are utilized to design, synthesize, and analyze Brown symbol performance. The theoretical performance in compression and dispersion of Brown symbols is demonstrated and is shown to exhibit significant improvement compared to discrete codes. As a result of this research a process is derived for the design of …

Space Time Adaptive Processing And Clutter Classification Integration And Evaluation, Nathan A. Jensen

Theses and Dissertations

Radar is a fundamental technology in today's military and civilian environment, and continuing development of this technology is of utmost importance to maintaining technological advantages this realm. Current radar technologies suffer from jamming and clutter limitations. STAP is a statistical method to remove this noise, however it is extremely computationally intensive, and presents several real time processing hurdles. Clutter Classification is another method to classify the radar returns that are found according to the best fit statistical distribution that the return follows. This research investigation attempts to use this clutter classification technology to aid in the detection of targets by …

Translation And Rotation Invariant Multiscale Image Registration, Jennifer L. Manfra

Theses and Dissertations

The most recent research involved registering images in the presence of translations and rotations using one iteration of the redundant discrete wavelet transform. We extend this work by creating a new multiscale transform to register two images with translation or rotation differences, independent of scale differences between the images. Our two-dimensional multiscale transform uses an innovative combination of lowpass filtering and the continuous wavelet transform to mimic the two-dimensional redundant discrete wavelet transform. This allows us to obtain multiple subbands at various scales while maintaining the desirable properties of the redundant discrete wavelet transform. Whereas the discrete wavelet transform produces …