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Articles 31 - 48 of 48
Full-Text Articles in Signal Processing
Computational Genomic Signatures And Metagenomics, Ozkan U. Nalbantoglu
Computational Genomic Signatures And Metagenomics, Ozkan U. Nalbantoglu
Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research
Mathematical characterizations of biological sequences form one of the main elements of bioinformatics. In this work, a class of DNA sequence characterization, namely computational genomics signatures, which capture global features of these sequences is used to address emerging computational biology challenges. Because of the species specificity and pervasiveness of genome signatures, it is possible to use these signatures to characterize and identify a genome or a taxonomic unit using a short genome fragment from that source. However, the identification accuracy is generally poor when the sequence model and the sequence distance measure are not selected carefully. We show that the …
Blind Deconvolution Method Of Image Deblurring Using Convergence Of Variance, Quentin D. Macmanus
Blind Deconvolution Method Of Image Deblurring Using Convergence Of Variance, Quentin D. Macmanus
Theses and Dissertations
Images are used for both aerial and space imagery applications, including target detection and tracking. The current problem concerning objects in geosynchronous orbit is that they are dim and hard to resolve because of their distance. This work will further the combined effort of AFIT and AFRL to provide enhanced space situational awareness (SSA) and space surveillance. SSA is critical in a time when many countries possess the technology to put satellites into orbit. Enhanced imaging technology improves the Air Force's ability to see if foreign satellites or other space hardware are operating in the vicinity of our own assets …
Direction Finding With Mutually Orthogonal Antennas, David F. Chick
Direction Finding With Mutually Orthogonal Antennas, David F. Chick
Theses and Dissertations
Estimating the direction-of-arrival of incident electromagnetic plane waves (a.k.a. direction finding or DF) has typically been accomplished in the past using arrays of spatially separated antennas. The spatial separation produces a delay in each antenna's measured voltage due to the finite propagation time as the wave strikes each antenna in succession. In this thesis, we approach the problem differently by using three antennas that have been oriented in orthogonal directions but are co-located at the origin of a coordinate system. Being co-located, this mutually orthogonal arrangement of antennas cannot detect the propagation phase delay and must rely solely on the …
Characterization Of Noise Technology Radar Signal Detectability Using A Non-Cooperative Receiver, Daniel V. Atienza
Characterization Of Noise Technology Radar Signal Detectability Using A Non-Cooperative Receiver, Daniel V. Atienza
Theses and Dissertations
As Noise Technology Radar (NTR) systems emerge, there is a need for non-cooperative, non-matched filter detection and exploitation. This work is based on that need and AFIT's Noise Network (NoNET) radar system. These signals are associated with Low Probability of Detection/ Intercept (LPD/LPI) signals. Quadrature Mirror Filter Banks (QMFB) has been effectively used for non-cooperatively detecting structured LPD/LPI signals and extracting various waveform characteristics. However, the QMFB process performance with unstructured NTR signals was challenging and motivated a need for a transformed QMFB. This transform was based on AFIT research by Gronholz and Mims (G-M), who used a multi-channel receiver …
Effects Of Cyclic Prefix Jamming Versus Noise Jamming In Ofdm Signals, Amber L. Scott
Effects Of Cyclic Prefix Jamming Versus Noise Jamming In Ofdm Signals, Amber L. Scott
Theses and Dissertations
Signal jamming of an orthogonal frequency-division multiplexing (OFDM) signal is simulated in MATLAB. Two different means of jamming are used to see, which is a more efficient way to disrupt a signal using the same signal power. The first way is a basic additive white Gaussian noise (AWGN) jammer that equally jams the entire signal. The second way is an AWGN jammer that targets only the cyclic prefix (CP) of the signal. These two methods of jamming are simulated using different channel models and unknowns to get varying results. The three channel models used in the simulations are the no …
A Simple Non-Destructive Method For Characterizing Non-Dispersive, Low-Loss Dielectrics, Thomas S. Olney
A Simple Non-Destructive Method For Characterizing Non-Dispersive, Low-Loss Dielectrics, Thomas S. Olney
Theses and Dissertations
It is shown how permittivity can be extracted via time domain reflection data from a perfect electric conductor (PEC) backed planar sample of a low-loss, non-dispersive dielectric using two rectangular Ku-band waveguide aperture probes with attached PEC flange plates of the same geometry but different dimensions. Of critical importance is being able to identify the reflection from the edge of the flange plate in the parallel plate region created by the plate and the PEC backing of the sample. A signal processing method that takes advantage of physical insight into the geometry and superposition is developed for identifying this edge …
Signals Of Opportunity Navigation Using Wi-Fi Signals, Wilfred E. Noel
Signals Of Opportunity Navigation Using Wi-Fi Signals, Wilfred E. Noel
Theses and Dissertations
Since GPS is generally limited to areas with clear sky view, additional methods of navigation are currently being explored. This thesis explores navigation using Signals of Opportunity(SoOP). The signals chosen for evaluation in this thesis are the common Internet IEEE 802.11a/g signals, or Wi-Fi. This thesis presents SoOP navigation based on cross-correlations of received data from multiple Wi-Fi stations. It shows the effectiveness of the methods using collected Wi-Fi signals in a real-world environment. By using simple statistical representations of collected data in large groups, or windows, cross-correlation calculations can produce timing offsets between simulated stations. The timing offsets, or …
Simultaneous Range/Velocity Detection With An Ultra-Wideband Random Noise Radar Through Fully Digital Cross-Correlation In The Time Domain, James R. Lievsay
Simultaneous Range/Velocity Detection With An Ultra-Wideband Random Noise Radar Through Fully Digital Cross-Correlation In The Time Domain, James R. Lievsay
Theses and Dissertations
This research effort examines the theory, application, and results of applying two-dimensional cross-correlation in the time domain to ultra-wideband (UWB) random noise waveforms for simultaneous range and velocity estimation. When applying common Doppler processing techniques to random noise waveforms for the purpose of velocity estimation, the velocity resolution degrades as the signal bandwidth or the target speed increase. To mitigate the degradation, the Doppler approximation is not utilized, and instead, wideband signal processing theory is applied in the time domain. The results show that by accurately interpolating each sample in the digitized reference signal, a target's velocity and range can …
Bistatic 3d Electromagnetic Scattering From A Right-Angle Dihedral At Arbitrary Orientation And Position, Andreas Z. Tempelis
Bistatic 3d Electromagnetic Scattering From A Right-Angle Dihedral At Arbitrary Orientation And Position, Andreas Z. Tempelis
Theses and Dissertations
A method is created to extend a bistatic 3D electromagnetic scattering solution for a dihedral at a given orientation and position to the case of arbitrary orientation and position. Results produced using this method are compared to shooting and bouncing rays (SBR) and method of moments (MoM) predictions, as well as measured data for applicable cases. The model in this thesis shows excellent agreement in magnitude and phase with SBR predictions. It also shows good agreement in magnitude with MoM predictions. Small phase differences between model and MoM data occur due to differences in the underlying scattering solution and the …
Electric Guitar Amplifier With Digital Effects, Shawn Garrett
Electric Guitar Amplifier With Digital Effects, Shawn Garrett
Computer Engineering
During the course of this project, the research and development of an electric guitar amplifier was undertaken. This amplifier is divided into three distinct sections. The power distribution circuitry provides the proper voltages to safely operate all necessary components. The DSP and digital effects stage provides processing and allows the user to add digital effects to the original guitar sound. The amplification stage increases the power of the input signal to drive a loudspeaker. Due to several setbacks throughout the course of this project, the overall amplifier was not completed. All three of the sections were developed to working functionality, …
Intelligibility Of Electrolarynx Speech Using A Novel Hands-Free Actuator, Brian Madden, Mark Nolan, Ted Burke, James Condron, Eugene Coyle
Intelligibility Of Electrolarynx Speech Using A Novel Hands-Free Actuator, Brian Madden, Mark Nolan, Ted Burke, James Condron, Eugene Coyle
Conference Papers
During voiced speech, the larynx provides quasi-periodic acoustic excitation of the vocal tract. In most electrolarynxes, mechanical vibrations are produced by a linear electromechanical actuator, the armature of which percusses against a metal or plastic plate at a frequency within the range of glottal excitation. In this paper, the intelligibility of speech produced using a novel hands-free actuator is compared to speech produced using a conventional electrolarynx. Two able-bodied speakers (one male, one female) performed a closed response test containing 28 monosyllabic words, once using a conventional electrolarynx and a second time using the novel design. The resulting audio recordings …
Augmented Control Of A Hands-Free Electrolarynx, Brian Madden, James Condron, Eugene Coyle
Augmented Control Of A Hands-Free Electrolarynx, Brian Madden, James Condron, Eugene Coyle
Conference Papers
During voiced speech, the larynx acts as the sound source, providing a quasi-periodic excitation of the vocal tract. Following a total laryngectomy, some people speak using an electrolarynx which employs an electromechanical actuator to perform the excitatory function of the absent larynx. Drawbacks of conventional electrolarynx designs include the monotonic sound emitted, the need for a free-hand to operate the device, and the difficulty experienced by many laryngectomees in adapting to its use. One improvement to the electrolarynx, which clinicians and users frequently suggest, is the provision of a convenient hands-free control facility. This would allow more natural use of …
Freeing Space For Nasa: Incorporating A Lossless Compression Algorithm Into Nasa's Fiber Optic Strain Sensing System, Kaitlyn Fiechtner, Allen Parker
Freeing Space For Nasa: Incorporating A Lossless Compression Algorithm Into Nasa's Fiber Optic Strain Sensing System, Kaitlyn Fiechtner, Allen Parker
STAR Program Research Presentations
NASA’s Fiber Optic Strain Sensing (FOSS) system can gather and store up to 1,536,000 bytes (1.46 megabytes) per second. Since the FOSS system typically acquires hours—or even days—of data, the system can gather hundreds of gigabytes of data for a given test event. To store such large quantities of data more effectively, NASA is modifying a Lempel-Ziv-Oberhumer (LZO) lossless data compression program to compress data as it is being acquired in real time. After proving that the algorithm is capable of compressing the data from the FOSS system, the LZO program will be modified and incorporated into the FOSS system. …
Tempo Detection Using A Hybrid Multi-Band Approach, Mikel Gainza, Eugene Coyle
Tempo Detection Using A Hybrid Multi-Band Approach, Mikel Gainza, Eugene Coyle
Articles
In this paper, a novel tempo detection system is presented, which suggests the use of a hybrid multiband decomposition. The model tracks the periodicities of different signal property changes that manifest within different frequency bands by using the most appropriate onset/transient detectors for each frequency band. In addition, the proposed system applies a novel method to weight tempo candidates. Each contribution is evaluated by comparing the presented system against existing approaches using three different databases that comprises 1638 songs. These databases include the two publicly available database of songs used in the tempo evaluation contest of ISMIR 2004. These songs …
The Synchronized Short-Time-Fourier-Transform: Properties And Definitions For Multichannel Source Separation., Ruairí De Fréin, Scott Rickard
The Synchronized Short-Time-Fourier-Transform: Properties And Definitions For Multichannel Source Separation., Ruairí De Fréin, Scott Rickard
Articles
This paper proposes the use of a synchronized linear transform, the synchronized short-time-Fourier-transform (sSTFT), for time-frequency analysis of anechoic mixtures. We address the short comings of the commonly used time-frequency linear transform in multichannel settings, namely the classical short-time-Fourier-transform (cSTFT). We propose a series of desirable properties for the linear transform used in a multichannel source separation scenario: stationary invertibility, relative delay, relative attenuation, and finally delay invariant relative windowed-disjoint orthogonality (DIRWDO). Multisensor source separation techniques which operate in the time-frequency domain, have an inherent error unless consideration is given to the multichannel properties proposed in this paper. The sSTFT …
On Improving Electrooculogram-Based Computer Mouse Systems: The Accelerometer Trigger, Johnalan Keegan, Edward Burke, James Condron, Eugene Coyle
On Improving Electrooculogram-Based Computer Mouse Systems: The Accelerometer Trigger, Johnalan Keegan, Edward Burke, James Condron, Eugene Coyle
Conference Papers
Eye tracking is a well-established method of computer control for profoundly paralysed people (Anson et al., 2002). Cameras are commonly used to track eye movements (Morimoto et al., 2005) but one alternative is the bioelectrical signal known as the electrooculogram (EOG). There are some EOG mouse control systems that facilitate the use of GUI applications, but certain actions, which are straightforward using a conventional mouse, remain impossible. Unless the eyes are tracking a target, they move in saccades (jumps), making it impossible to voluntarily trace out smooth trajectories with one's gaze, as would be required to draw a smooth curve. …
Application Of Stochastic Diffusion For Hiding High Fidelity Encrypted Images, Jonathan Blackledge, Abdulrahman Al-Rawi
Application Of Stochastic Diffusion For Hiding High Fidelity Encrypted Images, Jonathan Blackledge, Abdulrahman Al-Rawi
Articles
Cryptography coupled with information hiding has received increased attention in recent years and has become a major research theme because of the importance of protecting encrypted information in any Electronic Data Interchange system in a way that is both discrete and covert. One of the essential limitations in any cryptography system is that the encrypted data provides an indication on its importance which arouses suspicion and makes it vulnerable to attack. Information hiding of Steganography provides a potential solution to this issue by making the data imperceptible, the security of the hidden information being a threat only if its existence …
A Shock Tube Technique For Blast Wave Simulation And Studies Of Flow Structure Interactions In Shock Tube Blast Experiments, Nicholas N. Kleinschmit
A Shock Tube Technique For Blast Wave Simulation And Studies Of Flow Structure Interactions In Shock Tube Blast Experiments, Nicholas N. Kleinschmit
Department of Engineering Mechanics: Dissertations, Theses, and Student Research
Improvised explosive devices (IED’s) are widely used against US and allied forces fighting in Iraq and Afghanistan. Exposure to IED blast may cause blast-induced traumatic brain injury (bTBI). The injury mechanisms are however not well understood. A critical need in bTBI-related research is the ability to replicate the loading conditions of IED blast waves in a laboratory environment. In this work, experimental studies have been carried out to explore the use of the shock tube technique for generating air shock waves that mimic the temporal and spatial characteristics of free-field blast waves and to investigate the blast wave-test sample interactions …