By Topic

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

18-21 June 1996

Filter Results

Displaying Results 1 - 25 of 135
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Index

    Publication Year: 1996
    Request permission for commercial reuse | PDF file iconPDF (161 KB)
    Freely Available from IEEE
  • Identification of a class of time-varying nonlinear systems using basis sequences

    Publication Year: 1996, Page(s):161 - 164
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (420 KB)

    We consider the identification of a class of time-varying nonlinear systems, called the time-varying Hammerstein series. This identification problem is motivated by the practical need to characterise time-varying nonlinear systems in a simple and parsimonious manner. Basis sequences are introduced to facilitate a reduction in system parameterisation and also to make the estimation task tractable. ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Time-varying parametric modeling and simulation of ultrasonic Doppler signals

    Publication Year: 1996, Page(s):157 - 160
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (340 KB)

    A new approach for the simulation of nonstationary pulsed wave (PW) ultrasonic Doppler signals is proposed. The approach does not assume a theoretical power spectral density function for the PW Doppler signal and employs a time varying ARMA model whose parameters are approximated with a linear combination of Fourier base functions. Comparisons in both time and frequency domains show that the metho... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Applications of Wigner-Ville distribution on ERS-1 SAR images

    Publication Year: 1996, Page(s):293 - 296
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (420 KB)

    We propose here some utilizations of the Wigner-Ville distribution (WVD) for analysing ocean SAR images. It can be used for different purposes, the first one being the specific ability of the WVD for spectral analysis, especially with non-stationary signals. A second possible use is in the detection of roughness variations of the ocean surface, via the decrease of the spectrum around its maximum. ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Improved FM demodulation in a fading environment

    Publication Year: 1996, Page(s):9 - 12
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    Analog frequency modulation remains an important format for wireless communications, such as in the AMPS cellular telephone standard. Frequency modulation codes the signal as the instantaneous frequency of the transmitted waveform, so FM demodulation corresponds to the problem of instantaneous frequency (IF) estimation. Time-frequency methods have been shown to provide better IF estimates at low-S... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An iterative technique to design 2D QMF banks under constraints by the method of Lagrange multipliers

    Publication Year: 1996, Page(s):69 - 72
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    In order to design 2D FIR filters for near-perfect reconstruction, we study an iterative technique for designing 2D QMF banks without loosening the constraint of filter size. This technique allows one to solve the problem of the nonlinearity of the reconstruction equations and offers the possibility of introducing constraints derived from these equations by the method of Lagrange multipliers. We p... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An approach to the polynomial Wigner distributions

    Publication Year: 1996, Page(s):153 - 156
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (364 KB)

    The distribution concentration along the instantaneous frequency is one of the interesting research topics in time frequency analysis. The oldest and simplest transform for time-frequency signal representation is the short-time Fourier transform (STFT). However, it may achieve high concentration at the instantaneous frequency only for signals whose frequency is constant. The quality of the time-fr... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A wavelet based recursive reconstruction algorithm for linear measurements

    Publication Year: 1996, Page(s):33 - 36
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (336 KB)

    A recursive algorithm is proposed to obtain an efficient regularized least squares solution to large linear system of equations which arises in many physical measurement models. The algorithm recursively updates the solution in an increasingly larger dimensional subspace whose basis vectors are chosen as a subset of a complete wavelet basis. Robust criterions on how to chose the basis vectors at e... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Power class time-frequency representations: interference geometry, smoothing, and implementation

    Publication Year: 1996, Page(s):193 - 196
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (516 KB)

    The nth power class (PCn) of quadratic time-frequency representations (QTFRs) is specifically suited for the multiresolution analysis of signals passing through systems whose dispersion characteristic is approximately fκ. This paper considers several aspects of PC analysis important in applications. We discuss the geometry of PC auto terms and cross terms, and we propos... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 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»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Bayesian estimation of instantaneous frequency

    Publication Year: 1996, Page(s):5 - 8
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    The problem addressed in this paper is the Bayesian estimation of the instantaneous frequency for parametric nonstationary processes. We carry out Bayesian inference on the unknown parameters using powerful stochastic algorithms, the Markov chain Monte Carlo methods. Applications of such techniques to several models are presented and results of a simulation for one of those models are presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Automatic feature-finding for time-frequency distributions

    Publication Year: 1996, Page(s):333 - 336
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (868 KB)

    Given the detailed time and frequency resolution of time-frequency distributions, trainable automatic classifiers can easily be overwhelmed by the complexity of this input representation. This problem becomes even more severe as more advanced and higher resolution time-frequency distributions come into use. Our research is directed to making a better match to automatic classification by automatica... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.