Now showing items 21-40 of 49

    • 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 ...
    • Low Rank Estimation of Higher Order Statistics 

      Nowak, Robert David; Van Veen, Barry D. (1995-12-01)
      Low rank estimators for higher order statistics are considered in this paper. Rank reduction methods offer a general principle for trading estimator bias for reduced estimator variance. The bias-variance tradeoff is analyzed ...
    • Multifractal Formalism for Infinite Multinomial Measures 

      Riedi, Rudolf H.; Mandelbrot, Benoit (1995-01-20)
      There are strong reasons to believe that the multifractal spectrum of DLA shows anomalies which have been termed left sided. In order to show that this is compatible with strictly multiplicative structures Mandelbrot et ...
    • Multifractal Properties of TCP Traffic: a Numerical Study 

      Riedi, Rudolf H.; Vehel, Jacques (1997-10-20)
      We analyze two traces of TCP--traffic recorded at the gateway of a LAN corre­ sponding to two hours at Berkeley and to eight hours at CNET labs respectively. We are mainly interested in a multifractal approach, which we ...
    • Noise Reduction Using an Undecimated Discrete Wavelet Transform 

      Lang, Markus; Guo, Haitao; Odegard, Jan E.; Burrus, C. Sidney; Wells, R.O. (1995-01-15)
      A new nonlinear noise reduction method is presented that uses the discrete wavelet transform. Similar to Donoho and Johnstone, we employ thresholding in the wavelet transform domain but, following a suggestion by Coifman, ...
    • Nonlinear Wavelet Processing for Enhancement of Images 

      Odegard, Jan E.; Lang, Markus; Guo, Haitao; Gopinath, Ramesh A.; Burrus, C. Sidney (1994-05-20)
      In this note we apply some recent results on nonlinear wavelet analysis to image processing. In particular we illustrate how the (soft) thresholding algorithm due to Donoho and Johnstone can successfully be used to remove ...
    • 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 ...
    • Numerical Estimates of Generalized Dimensions D_q for Negative q 

      Riedi, Rudolf H. (1996-01-01)
      Usual fixed-size box-counting algorithms are inefficient for computing generalized fractal dimensions D(<i>q</i>) in the range of <i>q</i><0. In this Letter we describe a new numerical algorithm specifically devised to ...
    • 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 ...
    • An Overview of the AT&T Spoken Document Retrieval System 

      Choi, John; Hindle, Don; Hirschberg, Julia; Magrin-Chagnolleau, Ivan; Nakatani, Christine; Pereira, Fernando; Singhal, Amit; Whittaker, Steve (1998-01-15)
      We present an overview of a spoken document retrieval system developed at AT&T Labs-Research for the HUB4 Broadcast News corpus. This overview includes a description of the intonational phrase boundary detection, ...
    • 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 ...
    • 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 ...
    • Recent advances in Imaging and Spectroscopy with T-rays 

      Mittleman, Daniel M.; Neelamani, Ramesh; Gupta, Maya; Baraniuk, Richard G.; Nuss, Martin C. (1998-12-01)
      Recent work in terahertz "T-Ray" imaging is reported. With the ongoing development of commercially viable THz-TDS imaging system, opitmail signal processing strategies for the THz waveforms must be developed. Algorithms ...
    • SCAN - Speech Content Based Audio Navigator: A Systems Overview 

      Choi, John; Hindle, Don; Hirschberg, Julia; Magrin-Chagnolleau, Ivan; Nakatani, Christine; Pereira, Fernando; Singhal, Amit; Whittaker, Steve (1998-01-15)
      SCAN (Speech Content based Audio Navigator) is a spoken document retrieval system integrating speaker-independent, large-vocabulary speech recognition with information-retrieval to support query-based retrieval of information ...
    • Second-Order Statistical Measures for Text-Independent Speaker Identification 

      Bimbot, Frederic; Magrin-Chagnolleau, Ivan (1995-08-20)
      This article presents an overview of several measures for speaker recognition. These measures relate to second-order statistical tests, and can be expressed under a common formalism. Alternate formulations of these measures ...
    • 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, ...
    • A Simple Statistical Analysis of Wavelet-based Multifractal Spectrum Estimation 

      Goncalves, Paulo; Riedi, Rudolf H.; Baraniuk, Richard G. (1998-11-01)
      The multifractal spectrum characterizes the scaling and singularity structures of signals and proves useful in numerous applications, from network traffic analysis to turbulence. Of great concern is the estimation of the ...
    • Speaker Detection in Broadcast Speech Databases 

      Rosenberg, Aaron; Magrin-Chagnolleau, Ivan; Parthasarathy, S. (1998-01-15)
      Experiments have been carried out to assess the feasibility of detecting target speaker segments in multi-speaker broadcast databases. The experiemental database consists of NBC Nightly News broadcasts. The target speaker ...
    • Tensor Product Basis Approximations for Volterra Filters 

      Nowak, Robert David; Van Veen, Barry D. (1996-02-01)
      This paper studies approximations for a class of nonlinear filters known as Volterra filters. Although the Volterra filter provides a relatively simple and general representation for nonlinear filtering, often it is highly ...