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Proceedings of IEEE-SP International Symposium on Time- Frequency and Time-Scale Analysis

25-28 Oct. 1994

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Displaying Results 1 - 25 of 165
  • Wigner distribution and continuous wavelet transforms for image analysis: relationships and interpretation

    Publication Year: 1994, Page(s):314 - 317
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (334 KB)

    In this paper we discuss the relationships between space-scale, and space-frequency representations for 2D images. We compare the interpretation of the two representations and show that the affine smoothed Wigner distribution class may also be advantageously used in image processing.<> View full abstract»

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  • Non stationary signals classification using time-frequency distributions

    Publication Year: 1994, Page(s):233 - 236
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (313 KB)

    The paper deals with a comparison between different non-parametric classification methods of non stationary signals. The first ones, consider the time frequency representation (TFR) of the signal as the code itself and the decision is taken following the value of a dissimilarity index between the TFRs. In the other methods, the authors compute the instantaneous log-deviation between the (positive)... View full abstract»

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  • The why and how of time-frequency reassignment

    Publication Year: 1994, Page(s):197 - 200
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (400 KB)

    A general methodology providing a better readability of any bilinear distribution has been proposed. This methodology, referred to as reassignment, is essentially a generalization of an improvement of the spectrogram proposed by Kodera, Gendrin and de Villedary (1978). After a presentation of this original work, its generalization to a wide range of distributions is shown. The close connections of... View full abstract»

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  • Detection of stop consonants with the wavelet transform

    Publication Year: 1994, Page(s):612 - 615
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (331 KB)

    We present the burst detection of stop consonants in the French language with the wavelet transform. The system is based on the study of normalized correlation functions between the modulus of the impulse wavelet transform and the same transform of the speech signal. Every correlation function presents a minimum before each maximum, where that maximum is synchronous with the burst. Two signals S/s... View full abstract»

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  • Geometry of affine distributions

    Publication Year: 1994, Page(s):80 - 83
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (319 KB)

    Bilinear affine distributions are considered from the point of view of their geometry in the time-frequency plane. General construction rules are established for interference terms, with further interpretations in terms of localization properties and generalized means. In the case of frequency modulated signals, it is shown how the pointwise application of these rules can be refined by the study o... View full abstract»

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  • Time-frequency based distance and divergence measures

    Publication Year: 1994, Page(s):64 - 67
    Cited by:  Papers (19)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (330 KB)

    A study of the phase and amplitude sensitivity of the Renyi (1961) time-frequency information measure leads to the introduction of a new "Jensen-like" divergence measure. While this quantity promises to be a useful indicator of the distance between two time-frequency distributions, it is limited to the analysis of positive definite TFDs. In spite of this rather severe limitation, this measure coul... View full abstract»

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  • Proceedings of IEEE-SP International Symposium on Time- Frequency and Time-Scale Analysis

    Publication Year: 1994
    Request permission for commercial reuse | PDF file iconPDF (20 KB)
    Freely Available from IEEE
  • Wigner-Ville spectrum estimation via wavelet soft-thresholding

    Publication Year: 1994, Page(s):452 - 455
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    The high noise sensitivity of the Wigner distribution makes smoothing a necessity for producing readable time-frequency images of noise corrupted signals. Since linear smoothing suppresses noise at the expense of considerable smearing of the signal components, we explore two nonlinear denoising techniques based on soft-thresholding in an orthonormal basis representation. Soft-thresholding provides... View full abstract»

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  • Optimal estimation of time-frequency representations from corrupted observations

    Publication Year: 1994, Page(s):456 - 459
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (300 KB)

    Statistical time-frequency analysis is potentially very useful for estimating the parameters of nonstationary signals from measurements corrupted by nonstationary noise or interference which is a common situation in many signal processing applications. However, most existing time-frequency estimation techniques are ad hoc and invoke the quasi-stationarity assumption, which severely limits their sc... View full abstract»

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  • Quadratic time-varying spectral estimation for underspread processes

    Publication Year: 1994, Page(s):460 - 463
    Cited by:  Papers (15)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (324 KB)

    We study time-varying spectral estimation for nonstationary processes with restricted time-frequency (TF) correlation. We present explicit bias and variance expressions for quadratic TF-invariant (QTFI) estimators of an expected real-valued QTFI representation based on a single noisy observation. Unbiased theoretical estimators with globally minimal variance are derived and approximately realized ... View full abstract»

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  • Time-limited signals and Gabor expansion

    Publication Year: 1994, Page(s):268 - 271
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    Gabor (1946) expansion suffers from the consequences of the zero theorem which states that all continuous functions have a zero on the unit square in the Zak space. In particular the Gaussian function routinely selected for a window in the Gaborian analysis has a zero at (1/2,1/2). As a result a zero-matching scheme between the signal and the window must be employed, which limits the class of sign... View full abstract»

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  • Sub-band decomposition for projection magnetic resonance imaging of dynamic phenomena

    Publication Year: 1994, Page(s):580 - 583
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (244 KB)

    In this note we summarize some recent work concerning the imaging of time varying objects from a sequence of projections taken during the evolution of the object. Reconstruction of coarse features, corresponding to low spatial-frequency data, can be made nearly instantaneously in time from the evolving data. A temporal sequence of these low spatial-frequency reconstructions can be used to estimate... View full abstract»

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  • Smoothed multiple taper spectral analysis and adaptive implementation

    Publication Year: 1994, Page(s):464 - 467
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    A hybrid estimator of the log-spectral density of a stationary time series is proposed. First, a multiple taper estimate is performed, followed by kernel smoothing the log-multitaper estimate. This procedure reduces the expected mean square error by ((π2)/4)0.8 over simply smoothing the log tapered periodogram. The optimal number of tapers is O(N8(15/)). A data... View full abstract»

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  • Biomedical problems in time-frequency-scale analysis-new challenges

    Publication Year: 1994, Page(s):536 - 539
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    Biomedical problems are especially rich in the information they provide as an indication of the body's organ or system function. Information obtained from the human body is dynamic, time-varying, sometimes transient, mostly non-stationary, usually corrupted by noise. Time-frequency and time-scale analysis techniques are especially well suited to address such problems. Successful examples of applic... View full abstract»

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  • The computation of Weyl-Heisenberg coefficients for critically sampled and oversampled signals

    Publication Year: 1994, Page(s):272 - 275
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (212 KB)

    We present algorithms and implementations for Weyl-Heisenberg (W-H) coefficient computation of critically sampled and oversampled periodic discrete signals. In the oversampled case, both integer oversampling and fractional oversampling are investigated. Implementation results on single RISC processor of i860 and the Paragon parallel multiprocessor system are given for sampling sizes both of powers... View full abstract»

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  • Wavelet analysis as a potential tool for seizure detection

    Publication Year: 1994, Page(s):584 - 587
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (248 KB)

    Long-term monitoring of electroencephalograms (EEGs) is a well established clinical procedure for sleep studies and in epileptology for capturing seizure activity and localizing epileptic foci. Good seizure detection schemes facilitate diagnosis of epilepsy and enhance the management of long-term EEG records. The authors investigate a new automated method based on the discrete wavelet decompositio... View full abstract»

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  • Electromagnetic phenomenology studies using a data-adaptive time-frequency representation

    Publication Year: 1994, Page(s):468 - 471
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    An adaptive time-frequency representation (TFR) based on a non-uniform tiling of the time-frequency plane is presented and applied to several radar scatterers. In the proposed TFR, several focusing times can be selected according to the local (non-dispersive) features of the data. The maximum available frequency band is utilized to provide good time-resolution for points close to the focusing poin... View full abstract»

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  • Extensive analysis of a QRS detector based on the dyadic wavelet transform

    Publication Year: 1994, Page(s):540 - 543
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    Provides an extensive analysis of the dyadic wavelet transform (D yWT) based QRS detector algorithm proposed in Kadambe et al. (1992). This includes the analysis of the algorithm on the entire (standardised) American Heart Association database. The accuracy of the DyWT detector is compared with that of the Hamilton-Tompkins, Okada and MOBD algorithms. None of these algorithms... View full abstract»

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  • Oversampled finite-discrete Gabor transforms

    Publication Year: 1994, Page(s):276 - 279
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (400 KB)

    This paper considers the construction and fast computation of non-periodic discretizations of the Gabor transform. We first derive a reasonable finite version of the continuous transform by discretizing the integrals over regular in the time-frequency domain. We next apply the novel decomposition of the Gabor transform presented by Redding and Newsam (see Proceedings of the International Conferenc... View full abstract»

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  • Analysis of nonlinear cellular dynamics in the cochlea using the continuous wavelet transform and the short-time Fourier transform

    Publication Year: 1994, Page(s):588 - 591
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (256 KB)

    The continuous wavelet transform (CWT) and the short-time Fourier transform (STFT) are used to analyze the time course of cellular motion in the guinea-pig inner ear. The velocity responses of individual auditory cells (outer hair cells and Hensen's cells) to amplitude-modulated (AM) acoustical signals display characteristics typical of nonlinear systems, such as harmonic generation. Nonlinear eff... View full abstract»

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  • Application of wavelet transforms to ultrasonic NDE and remote-sensing signal analysis

    Publication Year: 1994, Page(s):472 - 475
    Cited by:  Papers (6)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    The use of discrete wavelet transforms and the discrete Gabor transforms in the ultrasonic NDE (nondestructive evaluation) and remote-sensing signal characterization and/or classification is considered. Both the NDE and the remote-sensing signals are likely to have multiple components which may be quite suitable for wavelet analysis. For the ultrasonic NDE signals, both the hidden geometrical defe... View full abstract»

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  • Coding of ECG signals by wavelet transform extrema

    Publication Year: 1994, Page(s):544 - 547
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (236 KB)

    A new electrocardiogram (ECG) coding method is presented. The method is based on storing the extrema of the wavelet transform of the ECG signal. The finite wavelet packet decomposition of the sampled ECG signal is obtained using the perfect reconstruction filterbank of the transform. The extrema of the resulting high-frequency subsignals are detected and the ones representing the clinically signif... View full abstract»

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  • Time-frequency analysis and observation synthesis of non-radial oscillations of white dwarfs

    Publication Year: 1994, Page(s):349 - 352
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    We reconstruct temporal spectra obtained from incomplete light-curve records of white dwarfs. The regularization of the corresponding inverse problem refers to band-limited interpolation and matching pursuit. A crucial point is the choice of the frequency support of the deconvolution. We show that matching pursuit, used as a complement to Fourier analysis, is a powerful tool for discriminating the... View full abstract»

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  • Oversampling in Gabor's signal expansion by an integer factor

    Publication Year: 1994, Page(s):280 - 283
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (324 KB)

    Gabor's (1946) expansion of a signal into a discrete set of shifted and modulated versions of an elementary signal is reviewed and its relation to sampling of the sliding-window spectrum is shown. It is indicated how Gabor's expansion coefficients can be found as samples of the sliding-window spectrum, where the window function, which still has to be determined, is related to the elementary signal... View full abstract»

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  • Narrow band frame multiresolution analysis with perfect reconstruction

    Publication Year: 1994, Page(s):36 - 39
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (244 KB)

    We define the notion of a frame multiresolution analysis (FMRA), and analyze its associated subband coding system. An important feature of this 2-band system is that the elements of the filter bank can be narrow band, unlike the half-band nature of a classical 2-band perfect reconstruction filter bank (PRFB). In the class of multiresolution structures, it is unnecessary to introduce FMRAs for perf... View full abstract»

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