Now showing items 1-59 of 59

  • An Adaptive Optimal-Kernel Time-Frequency Representation 

    Jones, Douglas L.; Baraniuk, Richard G. (1995-10-01)
    Time-frequency 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 

    Baraniuk, Richard G.; Jones, Douglas L.; Tom, Brotherton; Larry, Marple (1991-11-01)
    The authors describe the application of an adaptive optimal kernel (AOK) time-frequency representation to the processing of underwater acoustic data. The optimal kernel is a signal-dependent radially Gaussian function. ...
  • Beyond Time Frequency Analysis: Energy Densities in One and Many Dimensions 

    Baraniuk, Richard G. (1994-04-01)
    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 ...
  • Beyond Time Frequency Analysis: Energy Densities in One and Many Dimensions 

    Baraniuk, Richard G. (1998-09-01)
    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 ...
  • Blind Quadratic and Time Frequency Based Detectors from Training Data 

    Jones, Douglas L.; Sayeed, Akbar M. (1995-01-20)
    Time-frequency based methods, particularly quadratic (Cohen's-class) representations, are often considered for detection in applications ranging from sonar to machine monitoring. We propose a method of obtaining near-optimal ...
  • A Canonical Covariance Based Method for Generalized Joint Signal Representations 

    Jones, Douglas L.; Sayeed, Akbar M. (1996-04-20)
    Generalized joint signal representations extend the scope of joint time-frequency representations to a richer class of nonstationary signals. Cohen's marginal-based generalized approach is canonical from a distributional ...
  • Covariant Time Frequency Representations Through Unitary Equivalence 

    Baraniuk, Richard G. (1996-03-01)
    We propose a straightforward characterization of all quadratic time-frequency representations covariant to an important class of unitary signal transforms (namely, those having two continuous-valued parameters and an ...
  • Data Driven Signal Detection and Classification 

    Sayeed, Akbar M. (1997-01-20)
    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 time-frequency representations 

    Tobback, Tom; Steeghs, Philippe; Drijkoningen, Guy G; Fokkema, Jacob T (1996-01-15)
    In this paper we discuss the use of a time-frequency 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 

    Rizzoni, Giorgio; Sayeed, Akbar M.; Jones, Douglas L. (1996-01-20)
    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 

    Goncalves, Paulo; Riedi, Rudolf H. (2004-01-15)
    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 

    Venkatachalam, Vidya; Aravena, Jorge.L. (1999-05-01)
    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 

    Venkatachalam, Vidya; Aravena, Jorge.L. (1998-10-01)
    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 

    Sayeed, Akbar M.; Jones, Douglas L. (1996-12-20)
    Joint signal representations (JSRs) of arbitrary variables generalize time-frequency 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 

    Sayeed, Akbar M.; Jones, Douglas L. (1996-01-20)
    Generalized joint signal representations (JSRs) extend the scope of joint time-frequency 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 Time-Scale Analysis 

    Pasquier, Martin; Goncalves, Paulo; Baraniuk, Richard G. (1999-01-01)
    We introduce a new method for the time-scale analysis of non-stationary signals. Our work leverages the success of the "time-frequency distribution series / cross-term deleted representations" into the time-scale domain ...
  • Improved Time-Frequency Filtering of Signal-Averaged Electrocardiograms 

    Sayeed, Akbar M.; Jones, Douglas L. (1995-01-15)
    A recently proposed time-frequency filtering technique has shown promising results for the enhancement of signal-averaged electrocardiograms. This method weights the short-time Fourier transform (STFT) of the ensemble-averaged ...
  • Integral Transforms Covariant to Unitary Operators and their Implications for Joint Signal Representations 

    Sayeed, Akbar M.; Jones, Douglas L. (1996-06-01)
    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 

    Baraniuk, Richard G. (1998-10-01)
    In this paper, we propose a simple framework for studying certain distributions of variables beyond time-frequency and time-scale. 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 

    Baraniuk, Richard G. (1996-02-01)
    Recently, Cohen has proposed a construction for joint distributions of arbitrary physical quantities, in direct generalization of joint time-frequency representations. Actually this method encompasses two approaches, one ...
  • Marginals vs. Covariance in Joint Distribution Theory 

    Baraniuk, Richard G. (1995-05-01)
    Recently, Cohen has proposed a method for constructing joint distributions of arbitrary physical quantities, in direct generalization of joint time-frequency representations. In this paper, we investigate the covariance ...
  • Measuring Time-Frequency Information Content using the Renyi Entropies 

    Baraniuk, Richard G.; Flandrin, Patrick; Janssen, A. J. E. M.; Michel, Olivier (2001-05-01)
    The generalized entropies of Renyi inspire new measures for estimating signal information and complexity in the time-frequency plane. When applied to a time-frequency representation (TFR) from Cohen's class or the affine ...
  • Multiple Window Time Frequency Analysis 

    Bayram, Metin; Baraniuk, Richard G. (1996-06-01)
    We propose a robust method for estimating the time-varying spectrum of a non-stationary random process. Our approach extends Thomson's powerful multiple window spectrum estimation scheme to the time-frequency and time-scale ...
  • Multiple Window Time Varying Spectrum Estimation 

    Baraniuk, Richard G.; Bayram, Metin (2000-01-20)
    We overview a new non-parametric method for estimating the time-varying spectrum of a non-stationary random process. Our method extends Thomson's powerful multiple window spectrum estimation scheme to the time-frequency ...
  • Myoelectric Teleoperation of a Complex Robotic Hand 

    Farry, Kristin A; Walker, Ian D; Baraniuk, Richard G. (1996-10-01)
    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 

    Baraniuk, Richard G.; Jones, Douglas L. (1992-03-01)
    In this paper we propose a new class of signal analysis tools that generalizes the popular wavelet and short-time Fourier transforms. The class allows skews and rotations of the analyzing wavelet in the time-frequency ...
  • Nonlinear Wigner-Ville Spectrum Estimation using Wavelet Soft Thresholding 

    Baraniuk, Richard G. (1995-04-01)
    The large variance of the Wigner-Ville distribution makes smoothing essential for producing readable estimates of the time-varying power spectrum of noise corrupted signals. Since linear smoothing trades reduced variance ...
  • Nonstationary signal classification using pseudo power signatures 

    Venkatachalam, Vidya; Aravena, Jorge.L. (1998-06-20)
    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 

    Aravena, Jorge.L.; Venkatachalam, Vidya (1999-12-20)
    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 

    Venkatachalam, Vidya; Aravena, Jorge.L. (1996-03-20)
    Conventional signal processing typically involves frequency selective techniques which are highly inadequate for nonstationary signals. In this paper, we present an approach to perform time-frequency selective processing ...
  • On Joint Distributions for Arbitrary Variables 

    Baraniuk, Richard G.; Cohen, Leon (1995-01-01)
    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 

    Sayeed, Akbar M. (1997-04-20)
    Generalizing the concept of time-frequency 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 Time-Frequency Analysis 

    Wisur-Olsen, Fridtjof; Baraniuk, Richard G. (1996-05-01)
    We consider the design of kernels for time-frequency distributions through the phase, rather than amplitude, response. While phase kernels do not attenuate troublesome cross-components, they can translate them in the ...
  • Optimal Detection Using Bilinear Time Frequency and Time Scale Representations 

    Sayeed, Akbar M.; Jones, Douglas L. (1995-12-20)
    Bilinear time-frequency representations (TFRs) and time-scale 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 

    Sayeed, Akbar M.; Jones, Douglas L. (1995-02-20)
    Current theories of a time-varying 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 Time-Frequency Analysis 

    Wisur-Olsen, Fridtjof (1996-05-01)
    We consider the design of kernels for time-frequency distributions through the phase, rather than amplitude, response. While phase kernels do not attenuate troublesome cross-components, they can translate them in the ...
  • Optimal Phase Kernels for Time-Frequency Analysis 

    Baraniuk, Richard G.; Wisur-Olsen, Fridtjof (1996-01-01)
    We consider the design of kernels for time-frequency distributions through the phase, rather than amplitude, response. While phase kernels do not attenuate troublesome cross-components, they can translate them in the ...
  • Optimal Reduced Rank Time-Frequency/Time Scale Quadratic Detectors 

    Sayeed, Akbar M.; Jones, Douglas L. (1996-01-20)
    Optimal detectors based on time-frequency/time-scale 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 

    Sayeed, Akbar M.; Jones, Douglas L. (1996-12-01)
    Time-frequency analysis has recently undergone significant advances in two main directions: statistically optimized methods that extend the scope of time-frequency-based techniques from merely exploratory data analysis to ...
  • Pseudo Affine Wigner Distributions 

    Goncalves, Paulo; Baraniuk, Richard G. (1996-05-01)
    In this paper, we introduce a new set of tools for time-varying spectral analysis: the pseudo affine Wigner distributions. Based on the affine Wigner distributions of J. and P. Bertrand, these new time-scale distributions ...
  • Pseudo Affine Wigner Distributions: Definition and Kernel Formulation 

    Goncalves, Paulo; Baraniuk, Richard G. (1998-06-01)
    In this paper, we introduce a new set of tools for time-varying spectral analysis: the pseudo affine Wigner distributions. Based on the affine Wigner distributions of J. and P. Bertrand, these new time-scale distributions ...
  • Pseudo Power Scale Signatures: Frequency Domain Approach 

    Venkatachalam, Vidya; Aravena, Jorge.L. (2000-03-01)
    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 Pseudo-Bertrand Distribution for Time-Scale Analysis 

    Goncalves, Paulo; Baraniuk, Richard G. (1996-03-01)
    Using the pseudo-Wigner time-frequency distribution as a guide, we derive two new time-scale representations, the pseudo-Bertrand and the smoothed pseudo-Bertrand distributions. Unlike the Bertrand distribution, these ...
  • Shear Madness: New Orthonormal Bases and Frames Using Chirp Functions 

    Baraniuk, Richard G.; Jones, Douglas L. (1993-12-01)
    The proportional-bandwidth and constant-bandwidth time-frequency 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 

    Baraniuk, Richard G.; Jones, Douglas L. (1993-04-01)
    Time-frequency distributions (TFDs), which indicate the energy content of a signal as a function of both time and frequency, are powerful tools for time-varying signal analysis. The lack of a single distribution that is ...
  • Signal Transform Covariant to Scale Changes 

    Baraniuk, Richard G. (1993-09-01)
    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, ...
  • Signal-Dependent Time-Frequency Analysis using a Radially Gaussian Kernel 

    Baraniuk, Richard G.; Jones, Douglas L. (Elsevier, 1993-01-15)
    Time-frequency distributions are two-dimensional functions that indicate the time-varying frequency content of one-dimensional signals. Each bilinear time-frequency distribution corresponds to a kernel function that ...
  • A Signal-Dependent Time-Frequency Representation: Fast Algorithm for Optimal Kernel Design 

    Baraniuk, Richard G.; Jones, Douglas L. (1994-01-01)
    A time-frequency representation based on an optimal, signal-dependent kernel has been proposed recetnly in an attempte to overcome one of the primary limitations of bilinear time-frequency distributions: that the best ...
  • A Simple Covariance Based Characterization of Joint Signal Representations of Arbitrary Variables 

    Jones, Douglas L.; Sayeed, Akbar M. (1996-01-20)
    Joint signal representations of arbitrary variables extend the scope of joint time-frequency representations, and provide a useful description for a wide variety of nonstationary signal characteristics. Cohen's marginal-based ...
  • A Simple Scheme for Adapting Time-Frequency Representations 

    Jones, Douglas L.; Baraniuk, Richard G. (1994-12-01)
    Signal-dependent time-frequency 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 

    Steeghs, Philippe; Baraniuk, Richard G.; Odegard, Jan E. (CRC Press, 2002-01-15)
    In this chapter, we overview a number of applications of time-frequency representations in seismic data processing, from the analysis of seismic sequences to efficient attribute extraction to 3-D attributes for volumetric data.
  • Time Frequency Detectors 

    Sayeed, Akbar M.; Jones, Douglas L. (1996-01-20)
    Time-frequency representations (TFRs) provide a powerful and flexible structure for designing optimal detectors in a variety of nonstationary scenarios. In this paper, we describe a TFR-based framework for optimal detection ...
  • Time-Frequency Complexity and Information 

    Flandrin, Patrick; Baraniuk, Richard G.; Michel, Olivier (1994-04-01)
    Many functions have been proposed for estimating signal information content and complexity on the time-frequency plane, including moment-based measures such as the time-bandwidth product and the Shannon and Renyi entropies. ...
  • Time-frequency analysis of seismic sequences 

    Steeghs, Philippe; Drijkoningen, Guy G (1995-01-15)
    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. ...
  • Time-Frequency Based Distance and Divergence Measures 

    Michel, Olivier; Baraniuk, Richard G. (1994-10-01)
    A study of the phase and amplitude sensitivity of the recently proposed Renyi time-frequency information measure leads to the introduction of a new "Jensen-like" divergence measure. While this quantity promises to be a ...
  • Unitary Equivalence: A New Twist on Signal Processing 

    Baraniuk, Richard G.; Jones, Douglas L. (1995-10-01)
    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 

    Baraniuk, Richard G. (1994-10-01)
    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 

    Baraniuk, Richard G.; Jones, Douglas L. (1993-04-01)
    The notions of time, frequency, and scale are generalized using concepts from unitary operator theory and applied to time-frequency analysis, in particular the wavelet and short-time Fourier transform orthonormal bases and ...
  • Wigner-Based Formulation of the Chirplet Transform 

    Baraniuk, Richard G.; Jones, Douglas L. (1996-12-01)
    Using the Wigner distribution, we derive and analyze a matrix formulation for the chirplet transform, a signal analysis tool that generalizes the wavelet and short-time Fourier transforms. The formulation expresses the ...