Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 26 for “"Instantaneous Frequency"”.
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Implementation of Instantaneous Frequency Estimation based on Time-Varying AR Modeling
Instantaneous Frequency (IF) estimation based on time-varying autoregressive (TVAR) modeling has been shown to perform well in practical scenarios when the IF variation is rapid and/or non-linear and only short data records are available for modeling. A challenging aspect of implementing IF …
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Combined-channel instantaneous frequency analysis for audio source separation based on comodulation
… indicates that detecting common amplitude and frequency variation in acoustic signals plays an important role in the separation process. The physical mechanisms of sound generation in many sources cause common onsets/offsets and correlated increases/decreases in both amplitude and frequency …
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An Instantaneous Frequency Based Approach to Estimate Heart Rate and Calculate Heart Rate Variability Metrics
… associated with using R peaks to calculate instantaneous heart rate. In this study we present an alternative method (that does not rely on R peaks) based on the concept of instantaneous frequency to estimate heart rate from electrocardiogram (EKG) signals. The EKG signal is filtered to …
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Fast Chirped Signals for a TDMA Ultrasonic Indoor Positioning System
… for ultrasonic indoor positioning based on instantaneous frequency of ultrasonic signals is presented. Nonlinear phase characteristics of ultrasonic transducers introduce a frequency deviation in ultrasonic signals. By sweeping at very fast rates, a large spike in the deviation is …
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Analysis and filtering of time-varying signals
… sections are elementary signals. Mixed time-frequency representations (MTFRs) such as the Wigner distribution (WD), the Pseudo-Wigner distribution (PWD), the Short-time Fourier transform (STFT) and the optimally smoothed Wigner distribution (OSWD) used in analyzing STV signals are analyzed …
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Frequency Estimation Using Time-Frequency Based Methods
… of spectral parameters such as its amplitude, frequency, phase, and the variability of its instantaneous spectral components. The accuracy of these parameters depends on several processing variables such as resolution, noise level, and bias of the algorithm used. This thesis presents some …
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AM-FM methods for image and video processing
… of robust and efficient Amplitude-Modulation Frequency-Modulation (AM-FM) demodulation methods for image and video processing (there is currently a patent pending that covers the AM-FM methods and applications described in this dissertation). The motivation for this research lies in the wide …
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Particle filtering for frequency estimation from acoustic time-series in dispersive media
… methods to obtain accurate estimates of instantaneous frequencies using Short Term Fourier Transforms within the acoustic field measured at an array of hydrophones, which can be used in a subsequent step for the estimation of propagation related parameters. We develop a particle filter to …
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Interpretation and Fracture Characterization of Early-Cretaceous Buda Limestone Formation Using Post-Stack 3D Seismic Data in Zavala County, Texas
… along with physical seismic attributes such as instantaneous amplitude and instantaneous frequency. This study indicates that a combination of acoustic impedance inversion and seismic attributes can identify areas of enhanced natural fracturing within the Buda Limestone interval.</p>
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Polar frequency discriminators
This dissertation makes a study of frequency discriminators and their role in instantaneous frequency measuring (IFM) signal acquisition receivers. Frequency discriminators are the major building blocks of IFM. They are required to measure frequency accurately over very broad bandwidths and to have …
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Exploring fundamental physics with gravitational waves
… can provide a new method for searching for low-frequency GWs. This method is applied to searches for signals from individually resolvable supermassive black hole binaries. The main obstacle to performing efficient searches is the large size of the data sets, which consist of more than one …
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AM-FM Analysis of Structural and Functional Magnetic Resonance Images
… of multi-dimensional Amplitude-Modulation Frequency-Modulation (AM-FM) methods to magnetic resonance images (MRI). The basic goal is to provide a framework for exploring non-stationary characteristics of structural and functional MRI (sMRI and fMRI). First, we provide a comparison framework …
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Adaptive Data Representation and Analysis
… signals that lies in the field of adaptive time-frequency analysis. It explains a current state-of-the-art work, named the Synchrosqueezed transform, in this field. Then it illustrates two proposed algorithms that use non-parametric regression to reveal the underlying os- cillatory patterns of …
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Co-channel interference rejection using a model-based demodulator
… (AMPS) and the narrowband version (NAMPS) use frequency modulation (FM) in a frequency division duplex mode. Because such systems typically use the same frequency bands in nearby cells, co-channel interference can be a significant problem. A typical digital implementation uses a quadrature …
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High harmonic generation by short laser pulses: time-frequency behavior and applications to attophysics
… gas atoms excited by an intense laser field at frequency ω<sub>1</sub> emit radiation of higher frequencies that are odd integer multiples of ω<sub>1</sub>. Driven by an infrared laser, high harmonic radiation can span from the optical into the extreme ultraviolet (XUV) frequency range. In this …
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Localized Kernel Methods for Signal Processing
… (SSO) is constructed using a localized kernel. Instantaneous frequency estimates are obtained via FFT-based filtering, then clustered and fitted with piecewise linear regression. The method operates without prior knowledge of the number of components and is shown to recover intersecting and …
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Time-Frequency Analysis and Filtering based on the Short-Time Fourier Transform
The joint time-frequency (TF) domain provides a convenient platform for signal analysis by involving the dimension of time in the frequency representation of a signal. A straightforward way to acquire localized knowledge about the frequency content of the signal at different times is to perform the …
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Wavelets Based on Second Order Linear Time Invariant Systems, Theory and Applications
… The new wavelets can have well defined Time-Frequency resolutions, and they have useful properties; a direct relation between the scale and the frequency, unique transform formulas that can be easily obtained for most elementary signals such as unit step, sinusoids, polynomials, and decaying …
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Computational Approaches To Epilepsy: Graph Networks For Localization And Multi-Model Approach For Prediction
… effective connectivity measures based on frequency-domain convergent cross-mapping (FD-CCM) and graph centrality, a robust model is developed. This approach is validated on challenging interictal recordings, demonstrating that integrating these novel graph features with established …
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Space/time/frequency methods in adaptive radar
… may be processed with various space, time and frequency techniques. Advanced radar systems are required to detect targets in the presence of jamming and clutter. This work studies the application of two types of radar systems. It is well known that targets moving along-track within a Synthetic …
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