[1992] Proceedings of the IEEE-SP International Symposium on Time-Frequency and Time-Scale Analysis

4-6 Oct. 1992

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  • Proceedings of the IEEE-SP International Symposium Time-Frequency and Time-Scale Analysis (Cat.No.92TH0478-8)

    Publication Year: 1992
    Request permission for commercial reuse | PDF file iconPDF (107 KB)
    Freely Available from IEEE
  • Automatic classification of active sonar data using time-frequency transforms

    Publication Year: 1992, Page(s):21 - 24
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    Automatic classification of active sonar signals using the Wigner-Ville transform (WVT), the wavelet transform (WT) and the scalogram is addressed. Features are extracted by integrating over regions in the time-frequency (TF) distribution, and are classified by a decision tree. Experimental results show classification and detection rates of up to 92% at -4 dB of SNR. The WT outperforms the WVT and... View full abstract»

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  • A unified framework for the Bertrand distribution and the Altes distribution: the new hyperbolic class of quadratic time-frequency distributions

    Publication Year: 1992, Page(s):27 - 30
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (336 KB)

    The Bertrand (1991) distribution, which is a member of the affine class of time-frequency distributions (TFDs), and the Altes (1970, 1990) distribution, which does not belong to any known class of TFDs, are studied. It is shown that both TFDs are closely related to a hyperbolic time-frequency geometry. Based on this geometry, a new hyperbolic class of TFDs which contains both the Bertrand distribu... View full abstract»

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  • Wavelet vector quantization of images

    Publication Year: 1992, Page(s):471 - 474
    Cited by:  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (572 KB)

    A scheme for very low bit rate coding of images is presented. A pyramidal structure, constructed from the wavelet decomposition of the original image on successive dyadic resolutions, serves as the basic representation of the image. Entropy-constrained vector quantization (ECVQ) is adopted to quantize various subimages lying on the pyramid levels. Optimal entropy coding of the resulted indices can... View full abstract»

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  • Polynomial Wigner-Ville distributions and time-varying higher-order spectra

    Publication Year: 1992, Page(s):31 - 34
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    The concept of reduced time-varying higher-order spectra based on polynomial Wigner-Ville distributions (PWVDs) is presented. Two members of a class of PWVDs are illustrated, each dedicated to a specific problem that cannot be optimally solved using Cohen's class of bilinear (second order) time-frequency distributions. Polynomial WVDs are shown to preserve or generalize many properties of the WVD.... View full abstract»

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  • Spectral estimation from subbands

    Publication Year: 1992, Page(s):69 - 72
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (260 KB)

    The results of previous work by the authors (see Conf. on Inform. Sci. and Syst., 1992) are used to prove that subband differential pulse-code modulation (DPCM) provides a coding gain over full-band DPCM for finite orders of prediction. The equivalence of linear prediction and autoregressive (AR) modeling equations are used to estimate source spectra from subbands. Subband decomposition of a sourc... View full abstract»

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  • Image coding using DCT of wavelet coefficients

    Publication Year: 1992, Page(s):475 - 478
    Cited by:  Patents (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (396 KB)

    A method to encode wavelet transformed (WT) images is described. WT decomposition of natural images preserves image structure within each subimage. Subsequent coding of this multiresolution representation can be achieved through techniques such as scalar/vector quantization (SQ/VQ). It is proposed that by transforming WT coefficients, a better result can be achieved in both compression ratio and o... View full abstract»

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  • Famlet, to be or not to be a wavelet?

    Publication Year: 1992, Page(s):335 - 338
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    A class of orthogonal time domain functions called famlets is introduced. Famlets are produced from their frequency domain representatives by using the inverse Fourier transform. The basic theory behind famlets and the famlet transform associated with them is formulated, and their usage in nonuniform resolution spectrum analysis is described. The similarities and dissimilarities of famlets and wav... View full abstract»

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  • Wold-Cramer evolutionary spectral estimators

    Publication Year: 1992, Page(s):115 - 118
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (228 KB)

    A nonstationary signal can be represented as the output of a linear time-varying system, characterized by Zadeh's system function, with white noise as input. The Wold-Cramer evolutionary spectrum is defined as the magnitude squared of this system function. Estimators are obtained by expressing the signal as a random time-varying amplitude modulating a complex exponential of a certain analysis freq... View full abstract»

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  • Application of eigenanalysis and tomography to time-frequency representations

    Publication Year: 1992, Page(s):35 - 38
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (236 KB)

    The author addresses the question of how to obtain the high accuracy inherent in Wigner representations while avoiding the artifacts caused by cross products between multiple signal components. One approach involves separation of the components of a multicomponent signal by means of eigenanalysis. Various distortions are deliberately introduced by differentiation, smoothing, and the use of time va... View full abstract»

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  • Computational efficiency of the Gabor transform

    Publication Year: 1992, Page(s):399 - 402
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (384 KB)

    The two-dimensional Gabor transform has been proposed as a model of the visual receptive field of the simple cells of the mammalian striate cortex. The authors analyze the computational steps needed to achieve this transformation and present typical execution times for several computers. The use of an adaptive iteration step size is shown to improve performance significantly. Computational require... View full abstract»

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  • Wavelets as a regularization technique for spectral density estimation

    Publication Year: 1992, Page(s):73 - 76
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (232 KB)

    Estimation of the spectral density S(f) of a stationary random process can be viewed as a nonparametric statistical estimation problem. A nonparametric approach based on a wavelet representation for the logarithm of the unknown S(f) is introduced. This approach offers the ability to capture significant components of S(f) at different resolution... View full abstract»

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  • Mean value jump detection using wavelet decomposition

    Publication Year: 1992, Page(s):181 - 184
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (252 KB)

    The problem of detecting a mean value jump of a stationary random process by means of the wavelet transform (WT) is studied. This is significant for general nonstationarity detection. The properties of the continuous and discrete transforms are investigated, and the SNR expression is derived. It is shown that the Haar wavelet is optimum with respect to this criterion, but the discrete wavelet tran... View full abstract»

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  • Multiresolution speech analysis with an analog cochlear model

    Publication Year: 1992, Page(s):433 - 436
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (252 KB)

    The limitations of uniform bandwidth analysis methods (such as the spectrogram) for broadband signals when both temporal and spectral resolution are important are discussed. Signal representation by an auditory periphery model based on neurophysiological data is described. The model exhibits wavelet-like properties. The temporal analysis of the response of the model yields accurate time and freque... View full abstract»

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  • Wavelet localization of the Radon transform in even dimensions

    Publication Year: 1992, Page(s):137 - 140
    Cited by:  Papers (14)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (284 KB)

    One of the phenomena associated with the Radon transform is the following: in odd dimensions, local values of a function f:Rn→R can be determined by local measurements of the integrals of f over (n-1)-dimensional hyperplanes; in even dimensions, local values are globally dependent on the integrals over hyperplanes. The wavelet transform ... View full abstract»

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  • Adaptive optimal decompositions with hybrid DCT-subband coding

    Publication Year: 1992, Page(s):479 - 482
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (224 KB)

    A generalization of the discrete wavelet transform, i.e., the hybrid subband coding decomposition is introduced. It consists of the application of adequate invertible operators at each level of decomposition (inner-and inter-subbands) before application of the next level of decomposition. An important application is hybrid discrete cosine-transform (DCT)-subband coding, which produces optimal loca... View full abstract»

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  • New signal-space orthonormal bases via the metaplectic transform

    Publication Year: 1992, Page(s):339 - 342
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    The discretization of the metaplectic transform (MT) is considered, and it is shown that it can lead to completely new orthonormal bases (ONBs) for the signal space of square integrable functions. Two new classes of bases, the scale-and-shear bases and the translation-and-shear bases, are derived to demonstrate the discretization process. Besides generalizing the current methods of generating time... View full abstract»

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  • An investigation of the Wigner model for texture discrimination

    Publication Year: 1992, Page(s):539 - 542
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (356 KB)

    The generic issue of texture discrimination using spectral methods is addressed. A computational method based on exploiting local spectral information of the image is presented. The method is based on the use of a two-dimensional Wigner distribution which allows a precise tracking in space of the frequency characteristics of an image. Performance is illustrated for a synthesized image and for natu... View full abstract»

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  • Measuring amplitude and frequency modulations in noise using multiband energy operators

    Publication Year: 1992, Page(s):3 - 6
    Cited by:  Papers (8)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    The statistical properties of the nonlinear energy operator Ψ( s)=(ds/dt)2-sd2 /dt2 and a related energy separation algorithm (ESA) are developed. The ESA uses Ψ to demodulate noisy AM-FM signals. The performance of Ψ and the ESA when applied to bandpass noisy AM-FM signals is examined. The predicted performa... View full abstract»

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  • A technique for estimating the parameters of multiple polynomial phase signals

    Publication Year: 1992, Page(s):119 - 122
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (300 KB)

    An iterative algorithm for estimating the parameters of multiple superimposed polynomial phase signals is presented. The algorithm is based on the ability of the discrete polynomial transform (DPT) to estimate the parameters of a polynomial phase signal in the presence of other interfering signals. The parameters of one of the signals having been estimated, it can be filtered out from the composit... View full abstract»

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  • Random wavelet representation of unvoiced speech

    Publication Year: 1992, Page(s):41 - 44
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (328 KB)

    The different types of speech noise are reviewed together with their first-order statistics. A theoretical framework is formulated for speech noise analysis in terms of time-frequency energy concentrations (spectral peaks, amplitude and phase modulation). This framework is based on the linear acoustic theory of speech production, and on the theory of random modulation. A synthesis scheme using ran... View full abstract»

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  • Computational accuracy and stability issues for the finite, discrete Gabor transform

    Publication Year: 1992, Page(s):403 - 406
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    A Gabor expansion may use highly nonorthogonal basis functions and consequently inherit accuracy and stability problems due to near singularity when computed digitally. Two methods to discretize the Gabor transform are studied from the viewpoint of controlling numerical properties: a Zak-transform-based method and a matrix method. Theoretical issues relating to the singular behavior of each are ci... View full abstract»

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  • Butterworth wavelets and adaptive echo cancellation

    Publication Year: 1992, Page(s):451 - 454
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (300 KB)

    Butterworth wavelets are introduced for wavelet analysis, and it is shown that they constitute a large class of orthonormal wavelets with some advantages. Wavelet and binary tree representations are compared, and cross terms that decrease the intelligibility are suppressed by carefully adjusting the cut-off frequency. Rational sampling is used to obtain nonaliased frequency bands. Structural freed... View full abstract»

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  • Multiscale reconstruction of tomographic images

    Publication Year: 1992, Page(s):219 - 222
    Cited by:  Papers (15)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    The reconstruction of a tomographic image from the wavelet transform of its projections with a given 1-D analyzing wavelet is studied. This procedure permits reconstruction of a 2-D wavelet decomposition of the image. The generated 2-D analyzing wavelet is a radial wavelet, closely related to the 1-D analyzing wavelet. Results for an X-ray computerized tomography scan medical image are presented View full abstract»

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  • Time-frequency and time-scale analysis of high resolution ECGs

    Publication Year: 1992, Page(s):77 - 80
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (292 KB)

    Electrocardiograms (ECGs) of patients prone to ventricular tachycardia present micropotentials which may be defined as low amplitude, high frequency signals. The use of the Wigner distribution (WD) and wavelet transform (WT) to detect such micropotentials in high resolution ECGs is investigated. The two methods are precisely compared on data from patients with and without ventricular tachycardia. ... View full abstract»

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