Proceedings of Third International Symposium on Time-Frequency and Time-Scale Analysis (TFTS-96)

18-21 June 1996

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  • Proceedings of Third International Symposium on Time-Frequency and Time-Scale Analysis (TFTS-96)

    Publication Year: 1996
    Request permission for commercial reuse | PDF file iconPDF (699 KB)
    Freely Available from IEEE
  • Ridges associated to continuous linear time-frequency representations of asymptotic and transient signals

    Publication Year: 1996, Page(s):177 - 180
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (393 KB)

    In most fields of experimental physics, signals to be considered possess evolutive spectral characteristics. This situation is encountered for instance when one deals with acoustic signals, from musical sounds to nondestructive evaluation (Guillemain and Kronland-Martinet, 1996). The characterization of such signals is improved if time-frequency techniques are used. The representations obtained th... View full abstract»

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  • Using Malvar wavelets for transient detection

    Publication Year: 1996, Page(s):229 - 232
    Cited by:  Papers (2)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (317 KB)

    This paper is devoted to the detection of transient acoustic signals in very low signal-to-noise ratio contexts. The proposed algorithm uses the adaptive Malvar wavelet transform. It leads to a partition of the signal which is "optimal" according to a criteria that tests the Gaussian nature of the segments. A statistic based on the kurtosis is computed from this segmentation. View full abstract»

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  • Redundancy in a frame of wavelets-based matched-filter

    Publication Year: 1996, Page(s):257 - 260
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (356 KB)

    We propose in this paper a formulation for the matched-filter (MF) based on the frame of wavelets. We precisely compare the performance of the time-domain MF to that of this wavelet-based MF, with respect to the level of redundancy of the sampling of the time-scale plane, or equivalently, of the frame. The main result is that the redundancy of the discrete wavelet transform, instead of improving t... View full abstract»

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  • Multiresolution image reconstruction by wavelet decomposition

    Publication Year: 1996, Page(s):281 - 284
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (551 KB)

    We present a method of image reconstruction based on wavelet decomposition. The method seeks to overcome the problem of noise amplification during the image reconstruction process. We decompose the raw image to be reconstructed into several wavelet planes and a residual image, we reconstruct each one independently using an iterative maximum likelihood algorithm. To control the process, we stop the... View full abstract»

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  • Abrupt changes detection in the time-frequency plane

    Publication Year: 1996, Page(s):285 - 288
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (387 KB)

    This paper deals with a comparison between two new non-parametric methods for detecting abrupt spectral changes in non-stationary signals. The first one consists in comparing two smoothed time-frequency representations (TFRs), as well as for parametric approaches, a long-time and a short-time model are compared. In front of abrupt changes, the instantaneous distance between the two TFRs will sharp... View full abstract»

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  • High-speed moving sources analysis

    Publication Year: 1996, Page(s):397 - 400
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    This article describes the first step of moving acoustic sources analysis. Time-frequency and time-scale tools are used to characterize the signal received on a fixed microphone. It permits one to improve localisation methods. Simulations are presented in case of a sinusoidal source. An experiment with a known source fixed on a high speed train (TGV) is carried out. Then, the signal of a TGV comin... View full abstract»

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  • An efficient subband decomposition based on the Hilbert transform for high-resolution spectral estimation

    Publication Year: 1996, Page(s):409 - 412
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    This paper deals with high-resolution frequency estimation for narrow-band plane waves. We propose an approach based on subband decomposition in the spectral domain to improve the performance of high-resolution analysis. This decomposition is based on the Hilbert transform for one and two-dimensional signals. This improvement is tested on ESPRIT and MEMP techniques. We first present the subband de... View full abstract»

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  • Classification of power distribution system fault currents using wavelets associated to artificial neural networks

    Publication Year: 1996, Page(s):421 - 424
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (401 KB)

    In a power distribution system with a resonant neutral grounding, traditional protection algorithms based on a steady state analysis are no longer adapted. Hence a good use of transients becomes essential. This paper deals with the possibility of using wavelet transform as a preprocess for artificial neural networks (ANN) in the algorithm of power system relays. The ANN decides, after training, if... View full abstract»

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  • Ultrasonic crack detection and modelization by wavelet analysis

    Publication Year: 1996, Page(s):485 - 488
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (311 KB)

    Wavelet analysis has been applied as a signal processing tool for ultrasonic crack detection at an interface. The basic idea is to discriminate between signatures in the time-frequency frame, precisely in the time-scale frame. The tool is also shown to be a good one to qualify modelizations of the interaction between waves and flaws. It also allows one to reject parasitic distorted signals. View full abstract»

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  • Multiresolution analysis scheme for ERS-1 image segmentation

    Publication Year: 1996, Page(s):489 - 492
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (568 KB)

    We exploit the speckle information to provide ERS-1 images segmentation into regions, with reference to roughness. We describe a new segmentation scheme by using multi-scale information related to multifractal dimensions. We show that two different natural regions will give on radar imaging different roughness. The roughness characteristic may be considered as preliminary segmentation criterion. T... View full abstract»

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  • Instantaneous frequency tracking of a sine wave phase modulation signal

    Publication Year: 1996, Page(s):501 - 504
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (324 KB)

    When a signal is modulated by a sine with a low index of modulation, the tracking of the instantaneous frequency encounters many difficulties. In the application of acoustic velocity measurement by means of laser Doppler anemometry, the limitations appear quite rapidly with the signal processing now available. The approaches, proposed assume a knowledge of the modulation frequency and need several... View full abstract»

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  • Supervised time-frequency reassignment

    Publication Year: 1996, Page(s):517 - 520
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (384 KB)

    The reassignment method has been proved to improve the time-frequency representation of deterministic signals and especially of "chirp-like" FM signals. Unfortunately, reassignment presents some limitations when broadband noise is present. In this case, the squeezing process yields peaked areas in noise-only regions: this drawback should be avoided, since a rather flat energy distribution should b... View full abstract»

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  • Index

    Publication Year: 1996
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    Freely Available from IEEE
  • An algorithm for positive time-frequency distributions

    Publication Year: 1996, Page(s):165 - 168
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (324 KB)

    The time-frequency distributions (TFDs) of Cohen's class provide a method for high-resolution representation of time-varying signals. This benefit does not come without cost; the most noticeable is the existence of negative values in most desirable fixed-kernel TFDs. We examine the relation between the negative values and several aspects of TFDs, such as cross terms and marginal properties. We sug... View full abstract»

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  • Improved spread-spectrum communication with a wavelet packet based transceiver

    Publication Year: 1996, Page(s):417 - 420
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (412 KB)

    In a previous work by Lindsey (see PhD. Dissertation, Ohio University, 1994) wavelet packet modulation was introduced as a viable coding and M-ary orthogonal modulation strategy for improved communication performance, especially in scenarios where traditional quadrature amplitude modulation (QAM) is currently in use. A most important application of wavelet packet modulation is in direct sequence s... View full abstract»

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  • Seismic signal detection with time-frequency models

    Publication Year: 1996, Page(s):345 - 348
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (296 KB)

    We start by reviewing the pattern of a seismic signal. Then, we apply a time-frequency analysis to the signal by means of the smoothed pseudo Wigner-Ville distribution (SPWVD) in order to obtain instantaneous frequency (if) information. Based on the time-frequency behavior, we estimate a pattern to characterize the seismic signal. At the same time, we analyze the energy signal envelope, which is t... View full abstract»

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  • Wigner-Ville distribution decomposition via wavelet packet transform

    Publication Year: 1996, Page(s):413 - 416
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (284 KB)

    A new time-frequency distribution is proposed in this paper. It is based on a combination of the Wigner-Ville distribution (WVD) decomposition and the wavelet packet transform. First, the input signal is optimally decomposed into frequency bands by a best basis selection. Then, each subsignal within a frequency band is represented by the WVD decomposition. Finally, the proposed decomposition is ob... View full abstract»

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  • Tracking of frequency in a time-frequency representation

    Publication Year: 1996, Page(s):341 - 344
    Cited by:  Papers (6)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (324 KB)

    For non-stationary signals, the evolution of frequency characteristics with time may bring useful information to approach the underlying physical process. Time-frequency representations may facilitate such an interpretation. Here, we consider a representation obtained by the ARCAP method, which is adapted to narrow band signals. At the end of the analysis, at each sampling date, the signal is char... View full abstract»

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  • Wavelet coefficients, quadrature mirror filters and the group SO(4)

    Publication Year: 1996, Page(s):45 - 48
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (260 KB)

    Let c=(cj)j∈ Z∈l2 and u(ξ) be its Fourier series. We consider the local or gauge group of linear transformations preserving the combined energy spectral density at angular frequencies offset by π, |u(ξ)|2+|u(ξ+π)|2, separately at each ξ∈[0,π]. This gauge transformation group consists of the mappings from [0,... View full abstract»

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  • Classification of non-stationary random signals using multiple hypotheses testing

    Publication Year: 1996, Page(s):245 - 248
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    We present a new non-stationary signal classification algorithm based on a time-frequency distribution and multiple hypothesis testing. The time-frequency distribution is used to construct a time-dependent quadratic discriminant function. At selected points in time we evaluate the discriminant function and form a set of statistics which are used to test multiple hypotheses. The multiple hypotheses... View full abstract»

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  • Instantaneous frequency estimation using the crossterm deleted Wigner representation (CDWR)

    Publication Year: 1996, Page(s):289 - 292
    Cited by:  Papers (3)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    In this paper, an instantaneous frequency (IF) estimator based on the crossterm deleted Wigner representation (CDWR) is described. The performance of this estimator is verified by deriving the mean and the variance of the estimate. It has been demonstrated that the estimator is unbiased minimum variance under certain constraints. The Cramer-Rao lower bound for the two types of signals considered h... View full abstract»

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  • Estimating covariances of locally stationary processes: consistency of best basis methods

    Publication Year: 1996, Page(s):337 - 340
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (348 KB)

    Mallat, Papanicolaou and Zhang [1995] have suggested a method for approximating the covariance of a locally stationary process by a covariance which is diagonal in an ideally constructed Coifman-Meyer [1991] basis of cosine packets. A natural question arising from their work is to translate approximation results into estimation results. In this paper we discuss the problem of estimation of the cov... View full abstract»

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  • Generalized-marginal time-frequency distributions

    Publication Year: 1996, Page(s):509 - 512
    Cited by:  Papers (4)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    We introduce a family of time-frequency (TF) distributions with generalized-marginals, i.e., beyond the time-domain and the frequency-domain marginals, in the sense that the projections of a TF distribution along one or more angles are equal to the magnitude squared of the fractional Fourier transforms of the signal. We present a necessary and sufficient condition for a TF distribution in the Cohe... View full abstract»

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  • Signal de-noising using adaptive Bayesian wavelet shrinkage

    Publication Year: 1996, Page(s):225 - 228
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (280 KB)

    Shrinkage of the empirical wavelet coefficients is an effective way to de-noise signals possessing sparse wavelet transforms. This article outlines a Bayesian approach to wavelet shrinkage, in which the form of the shrinkage function is induced by a particular choice of prior distributions placed on the wavelet coefficients. Our priors are chosen to be mixtures of two normal distributions, one wid... View full abstract»

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