Now showing items 1-18 of 18

  • 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 ...
  • 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 ...
  • 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 ...
  • 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 ...
  • 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 ...
  • Improved Wavelet Denoising via Empirical Wiener Filtering 

    Ghael, Sadeep; Sayeed, Akbar M.; Baraniuk, Richard G. (1997-07-01)
    Wavelet shrinkage is a signal estimation technique that exploits the remarkable abilities of the wavelet transform for signal compression. Wavelet shrinkage using thresholding is asymptotically optimal in a minimax ...
  • 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 ...
  • Multiuser detection in fast-fading multipath environments 

    Sayeed, Akbar M.; Sendonaris, Andrew; Aazhang, Behnaam (1998-12-20)
    We propose a new framework for multiuser detection in fast-fading channels that are encountered in many mobile communication scenarios. Existing multiuser RAKE receivers, developed to combat multipath fading and multiuser ...
  • Multiuser detection in fast-fading multipath environments 

    Sayeed, Akbar M.; Aazhang, Behnaam (2001-10-20)
    We propose a new framework for multiuser detection in fast-fading channels that are encountered in many mobile communication scenarios. Existing multiuser RAKE receivers, developed to combat multipath fading and multiuser ...
  • 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 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 ...
  • 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 ...
  • 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-Selective Signaling and Reception for Communication over Multipath Fading Channels 

    Bhashyam, Srikrishna; Sayeed, Akbar M.; Aazhang, Behnaam (2000-01-20)
    The mobile wireless channel affords inherent diversity to combat the effects of fading. Existing code division multiple access (CDMA) systems, by virtue of spread-spectrum signaling and RAKE reception, exploit only part ...