Browsing by Subject "Time Frequency and Spectral Analysis"
Now showing items 159 of 59

An Adaptive OptimalKernel TimeFrequency Representation
(19951001)Timefrequency representations with fixed windows or kernels figure prominently in many applications, but perform well only for limited classes of signals. Representations with signal dependent kernels can overcome this ... 
Applications of Adaptive Time Frequency Representations to Underwater Acoustic Signal Processing
(19911101)The authors describe the application of an adaptive optimal kernel (AOK) timefrequency representation to the processing of underwater acoustic data. The optimal kernel is a signaldependent radially Gaussian function. ... 
Beyond Time Frequency Analysis: Energy Densities in One and Many Dimensions
(19980901)Given a unitary operator A representing a physical quantity of interest, we employ concepts from group representation theory to define two natural signal energy densities for A. The first is invariant to A and proves ... 
Beyond Time Frequency Analysis: Energy Densities in One and Many Dimensions
(19940401)Given a unitary operator <i>A</i> representing a physical quantity of interest, we employ concepts from group representation theory to define two natural signal energy densities for <i>A</i>. The first is invariant to ... 
Blind Quadratic and Time Frequency Based Detectors from Training Data
(19950120)Timefrequency based methods, particularly quadratic (Cohen'sclass) representations, are often considered for detection in applications ranging from sonar to machine monitoring. We propose a method of obtaining nearoptimal ... 
A Canonical Covariance Based Method for Generalized Joint Signal Representations
(19960420)Generalized joint signal representations extend the scope of joint timefrequency representations to a richer class of nonstationary signals. Cohen's marginalbased generalized approach is canonical from a distributional ... 
Covariant Time Frequency Representations Through Unitary Equivalence
(19960301)We propose a straightforward characterization of all quadratic timefrequency representations covariant to an important class of unitary signal transforms (namely, those having two continuousvalued parameters and an ... 
Data Driven Signal Detection and Classification
(19970120)In many practical detection and classification problems, the signals of interest exhibit some uncertain nuisance parameters, such as the unknown delay and Doppler in radar. For optimal performance, the form of such parameters ... 
Decomposition of seismic signals via timefrequency representations
(19960115)In this paper we discuss the use of a timefrequency representation, the Wigner distribution, for the decomposition and characterization of seismic signals. The advantage of the Wigner distribution over other representations, ... 
Design of Training Data Based Quadratic Detectors with Application to Mechanical Systems
(19960120)Reliable detection of engine knock is an important issue in the design and maintenance of high performance internal combustion engines. Cost considerations dictate the use of vibration signals, measured at the engine ... 
Diverging moments and parameter estimation
(20040115)Heavy tailed distributions enjoy increased popularity and become more readily applicable as the arsenal of analytical and numerical tools grows. They play key roles in modeling approaches in networking, finance, hydrology ... 
Enhanced Pseudo Power Signatures for Nonstationary Signal Classification: The Projector Approach
(19990501)The classification of nonstationary signals of unknown duration is of great importance in areas like oil exploration, moving target detection, and pattern recognition. In an earlier work, we provided a solution to this ... 
Enhanced signatures for event classification: The projector approach
(19981001)The classification of nonstationary signals of unknown duration is of great importance in areas like oil exploration, moving target detection, and pattern recognition. In an earlier work, we provided a solution to this ... 
Equivalence of Generalized Joint Signal Representations of Arbitrary Variables
(19961220)Joint signal representations (JSRs) of arbitrary variables generalize timefrequency representations (TFRs) to a much broader class of nonstationary signal characteristics. Two main distributional approaches to JSRs of ... 
Generalized Joint Signal Representations and Optimum Detection
(19960120)Generalized joint signal representations (JSRs) extend the scope of joint timefrequency representations (TFRs) to a richer class of nonstationary signals, but their use, just as in the case of TFRs, has been primarily ... 
Hybrid Linear / Bilinear TimeScale Analysis
(19990101)We introduce a new method for the timescale analysis of nonstationary signals. Our work leverages the success of the "timefrequency distribution series / crossterm deleted representations" into the timescale domain ... 
Improved TimeFrequency Filtering of SignalAveraged Electrocardiograms
(19950115)A recently proposed timefrequency filtering technique has shown promising results for the enhancement of signalaveraged electrocardiograms. This method weights the shorttime Fourier transform (STFT) of the ensembleaveraged ... 
Integral Transforms Covariant to Unitary Operators and their Implications for Joint Signal Representations
(19960601)Fundamental to the theory of joint signal representations is the idea of associating a variable, such as time or frequency, with an operator, a concept borrowed from quantum mechanics. Each variable can be associated ... 
Joint Distributions of Arbitrary Variables Made Easy
(19981001)In this paper, we propose a simple framework for studying certain distributions of variables beyond timefrequency and timescale. When applicable, our results turn the theory of joint distributions of arbitrary variables ... 
A Limitation of the Kernel Method for Joint Distributions of Arbitrary Variables
(19960201)Recently, Cohen has proposed a construction for joint distributions of arbitrary physical quantities, in direct generalization of joint timefrequency representations. Actually this method encompasses two approaches, one ... 
Marginals vs. Covariance in Joint Distribution Theory
(19950501)Recently, Cohen has proposed a method for constructing joint distributions of arbitrary physical quantities, in direct generalization of joint timefrequency representations. In this paper, we investigate the covariance ... 
Measuring TimeFrequency Information Content using the Renyi Entropies
(20010501)The generalized entropies of Renyi inspire new measures for estimating signal information and complexity in the timefrequency plane. When applied to a timefrequency representation (TFR) from Cohen's class or the affine ... 
Multiple Window Time Frequency Analysis
(19960601)We propose a robust method for estimating the timevarying spectrum of a nonstationary random process. Our approach extends Thomson's powerful multiple window spectrum estimation scheme to the timefrequency and timescale ... 
Multiple Window Time Varying Spectrum Estimation
(20000120)We overview a new nonparametric method for estimating the timevarying spectrum of a nonstationary random process. Our method extends Thomson's powerful multiple window spectrum estimation scheme to the timefrequency ... 
Myoelectric Teleoperation of a Complex Robotic Hand
(19961001)Teleoperation continues to be a primary control mode in robotics applications, particularly for robots with complex hands. This paper details a novel method of teleoperation of complex anthropomorphic robotic hands: ... 
New Dimensions In Wavelet Analysis
(19920301)In this paper we propose a new class of signal analysis tools that generalizes the popular wavelet and shorttime Fourier transforms. The class allows skews and rotations of the analyzing wavelet in the timefrequency ... 
Nonlinear WignerVille Spectrum Estimation using Wavelet Soft Thresholding
(19950401)The large variance of the WignerVille distribution makes smoothing essential for producing readable estimates of the timevarying power spectrum of noise corrupted signals. Since linear smoothing trades reduced variance ... 
Nonstationary signal classification using pseudo power signatures
(19980620)This paper deals with the problem of classification of nonstationary signals using signatures which are essentially independent of the signal length. We develop the notion of a separable approximation to the Continuous ... 
Nonstationary signal classification using pseudo power signatures: The Matrix SVD Approach
(19991220)This paper deals with the problem of classification of nonstationary signals using signatures which are essentially independent of the signal length. This independence is a requirement in common classification problems ... 
Nonstationary Signal Enhancement Using The Wavelet Transform
(19960320)Conventional signal processing typically involves frequency selective techniques which are highly inadequate for nonstationary signals. In this paper, we present an approach to perform timefrequency selective processing ... 
On Joint Distributions for Arbitrary Variables
(19950101)There has been considerable interest in the problem of joint representations for variables other than time and frequency. In this letter we compare the methods of Cohen and of Baraniuk and Jones and show their equivalence ... 
On the Equivalence of the Operator and Kernel Methods for Joint Distributions of Arbitrary Variables
(19970420)Generalizing the concept of timefrequency representations, Cohen has recently proposed a general method, based on operator correspondence rules, for generating joint distributions of arbitrary variables. As an alternative ... 
Opitmal Phase Kernels for TimeFrequency Analysis
(19960501)We consider the design of kernels for timefrequency distributions through the phase, rather than amplitude, response. While phase kernels do not attenuate troublesome crosscomponents, they can translate them in the ... 
Optimal Detection Using Bilinear Time Frequency and Time Scale Representations
(19951220)Bilinear timefrequency representations (TFRs) and timescale representations (TSRs) are potentially very useful for detecting a nonstationary signal in the presence of nonstationary noise or interference. As quadratic ... 
Optimal Kernels for Nonstationary Spectral Estimation
(19950220)Current theories of a timevarying spectrum of a nonstationary process all involve, either by definition or by difficulties in estimation, an assumption that the signal statistics vary slowly over time. This restrictive ... 
Optimal Phase Kernels for TimeFrequency Analysis
(19960501)We consider the design of kernels for timefrequency distributions through the phase, rather than amplitude, response. While phase kernels do not attenuate troublesome crosscomponents, they can translate them in the ... 
Optimal Phase Kernels for TimeFrequency Analysis
(19960101)We consider the design of kernels for timefrequency distributions through the phase, rather than amplitude, response. While phase kernels do not attenuate troublesome crosscomponents, they can translate them in the ... 
Optimal Reduced Rank TimeFrequency/Time Scale Quadratic Detectors
(19960120)Optimal detectors based on timefrequency/timescale representations (TFRs/TSRs) admit a representation in terms of a bank of spectrograms/scalograms that yields a large class of detectors. These range from the conventional ... 
Optimum Quadratic Detection and Estimation Using Generalized Joint Signal Representations
(19961201)Timefrequency analysis has recently undergone significant advances in two main directions: statistically optimized methods that extend the scope of timefrequencybased techniques from merely exploratory data analysis to ... 
Pseudo Affine Wigner Distributions
(19960501)In this paper, we introduce a new set of tools for timevarying spectral analysis: the pseudo affine Wigner distributions. Based on the affine Wigner distributions of J. and P. Bertrand, these new timescale distributions ... 
Pseudo Affine Wigner Distributions: Definition and Kernel Formulation
(19980601)In this paper, we introduce a new set of tools for timevarying spectral analysis: the pseudo affine Wigner distributions. Based on the affine Wigner distributions of J. and P. Bertrand, these new timescale distributions ... 
Pseudo Power Scale Signatures: Frequency Domain Approach
(20000301)In an earlier work, we introduced a new form of signal representation called the <b><i>pseudo power signature (PPS)</i></b> that was essentially independent of the duration of the signal. The signatures were obtained based ... 
A PseudoBertrand Distribution for TimeScale Analysis
(19960301)Using the pseudoWigner timefrequency distribution as a guide, we derive two new timescale representations, the pseudoBertrand and the smoothed pseudoBertrand distributions. Unlike the Bertrand distribution, these ... 
Shear Madness: New Orthonormal Bases and Frames Using Chirp Functions
(19931201)The proportionalbandwidth and constantbandwidth timefrequency signal decompositions of the wavelet, Gabor, and Wilson orthonormal bases have attracted substantial interest for representing nonstationary signals. However, ... 
A Signal Dependent Time Frequency Representation: Optimal Kernel Design
(19930401)Timefrequency distributions (TFDs), which indicate the energy content of a signal as a function of both time and frequency, are powerful tools for timevarying signal analysis. The lack of a single distribution that is ... 
Signal Transform Covariant to Scale Changes
(19930901)A unitary signal transformation that is covariant by translation to scale changes (dilations and compressions) in the signal is formulated and justified. Unlike the Mellin transform, which is invariant to scale changes, ... 
SignalDependent TimeFrequency Analysis using a Radially Gaussian Kernel
(19930115)Timefrequency distributions are twodimensional functions that indicate the timevarying frequency content of onedimensional signals. Each bilinear timefrequency distribution corresponds to a kernel function that ... 
A SignalDependent TimeFrequency Representation: Fast Algorithm for Optimal Kernel Design
(19940101)A timefrequency representation based on an optimal, signaldependent kernel has been proposed recetnly in an attempte to overcome one of the primary limitations of bilinear timefrequency distributions: that the best ... 
A Simple Covariance Based Characterization of Joint Signal Representations of Arbitrary Variables
(19960120)Joint signal representations of arbitrary variables extend the scope of joint timefrequency representations, and provide a useful description for a wide variety of nonstationary signal characteristics. Cohen's marginalbased ... 
A Simple Scheme for Adapting TimeFrequency Representations
(19941201)Signaldependent timefrequency representations, by adapting their functional form to fit the signal being analyzed, offer many performance advantages over conventional representations. In this paper, we propose a simple, ... 
Time Frequency Analysis Applications in Geophysics
(20020115)In this chapter, we overview a number of applications of timefrequency representations in seismic data processing, from the analysis of seismic sequences to efficient attribute extraction to 3D attributes for volumetric data. 
Time Frequency Detectors
(19960120)Timefrequency representations (TFRs) provide a powerful and flexible structure for designing optimal detectors in a variety of nonstationary scenarios. In this paper, we describe a TFRbased framework for optimal detection ... 
TimeFrequency Complexity and Information
(19940401)Many functions have been proposed for estimating signal information content and complexity on the timefrequency plane, including momentbased measures such as the timebandwidth product and the Shannon and Renyi entropies. ... 
Timefrequency analysis of seismic sequences
(19950115)Reflection patterns play an important role in seismic sequence stratigraphy, therefore making their quantitative description essential for the construction and validation of sequence stratigraphic models from seismic data. ... 
TimeFrequency Based Distance and Divergence Measures
(19941001)A study of the phase and amplitude sensitivity of the recently proposed Renyi timefrequency information measure leads to the introduction of a new "Jensenlike" divergence measure. While this quantity promises to be a ... 
Unitary Equivalence: A New Twist on Signal Processing
(19951001)Unitary similarity transformations furnish a powerful vehicle for generating infinite generic classes of signal analysis and processing tools based on concepts different from time, frequency, and scale. Implementation of ... 
Warped Perspectives in Time Frequency Analysis
(19941001)Unitary similarity transformations furnish a simple yet powerful vehicle for generating new classes of joint distributions based on concepts different from time, frequency, and scale. These new signal representations ... 
Warped Wavelet Bases: Unitary Equivalence and Signal Processing
(19930401)The notions of time, frequency, and scale are generalized using concepts from unitary operator theory and applied to timefrequency analysis, in particular the wavelet and shorttime Fourier transform orthonormal bases and ... 
WignerBased Formulation of the Chirplet Transform
(19961201)Using the Wigner distribution, we derive and analyze a matrix formulation for the chirplet transform, a signal analysis tool that generalizes the wavelet and shorttime Fourier transforms. The formulation expresses the ...