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Time-Frequency and Time-Scale Analysis, 1994., Proceedings of the IEEE-SP International Symposium on

Date 25-28 Oct. 1994

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Displaying Results 1 - 25 of 165
  • 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
  • Time-frequency peak filtering: analysis and implementation details

    Publication Year: 1994, Page(s):256 - 259
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    Time-frequency peak filtering is a novel technique for signal filtering and enhancement. The method is based upon encoding the signal as an instantaneous frequency (IF) and using IF analysis techniques to recover a filtered version of it. A general iterative time-frequency peak filtering (TFPF) scheme based on this method has been formulated. In this contribution we give details of bias and varian... View full abstract»

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  • A new method for the design of high performance receivers in the presence of co-channel interference

    Publication Year: 1994, Page(s):496 - 499
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (284 KB)

    We present the co-channel interference mitigation in the time-scale domain (CIMTS) algorithm which estimates the signal of interest (SOI) and the interfering signal from their superposition in the presence of additive noise. This method is inspired by the reconstruction of the interference from the null space of the SOI in the time-scale domain. Once the null space of the SOI is determined, the in... View full abstract»

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  • A novel adaptive time-frequency excision technique for direct sequence spread spectrum communications

    Publication Year: 1994, Page(s):492 - 495
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    A novel, adaptive time-frequency (ATF) exciser for suppressing the interference in direct sequence spread spectrum (DSSS) communications systems is proposed. The adaptability of the proposed algorithm is two-fold. First, the domain of excision is decided. Then, for time-localized interference, excision is performed in the time domain. For a frequency-localized interference, an adaptive subband tra... 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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  • Time-frequency representations using a radial Butterworth kernel

    Publication Year: 1994, Page(s):60 - 63
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    A new radial Butterworth kernel (RBK) with two adjustable parameters for the Cohen's (1966) class of distributions (CCD) is presented in the ambiguity function domain. It is particularly suitable for signals with a high degree of of nonstationarity and, by adjusting these parameters, the resulting time-frequency distribution can effectively suppress the crossterms while retaining the autoterms. Nu... View full abstract»

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  • Design of an optimum wavelet for cancellation of long echoes in telephony

    Publication Year: 1994, Page(s):488 - 491
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    The application of wavelet packet (WP) in the echo cancellation is investigated and its performance is discussed. An efficient algorithm is developed to design a set of optimal wavelet filter banks for echo cancellation. Experimental results show that with the optimum wavelet filter banks, the output echo energy can be minimized and the computation load can be reduced View full abstract»

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  • Adaptive filtering based on wavelet decomposition

    Publication Year: 1994, Page(s):260 - 263
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (252 KB)

    Addresses a novel, wavelet decomposition based adaptive filtering technique. The input signal is decomposed into octave-bands and the adaptive filtering is performed on those signals using a hierarchical structure. The signal error is decomposed and used in the adaptation process. Using this technique, considerable computational reduction is achieved over the full-band scheme. Simulations show tha... View full abstract»

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  • Joint representation in time and frequency scale for harmonic type signals

    Publication Year: 1994, Page(s):84 - 87
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (268 KB)

    When a periodic waveform is modulated the resulting signal consists of a fundamental which has broadness in frequency and the sum of functions that are scaled and/or shifted versions of the fundamental. We present a method to study such functions and present an example using a speech signal View full abstract»

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  • Time-frequency analysis of frames

    Publication Year: 1994, Page(s):52 - 55
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    The theory of frames is fundamental to time-frequency (TF) or time-scale signal expansions like Gabor expansions and wavelet transforms. We propose a TF analysis of frames via two “TF frame representations” called the Weyl symbol and Wigner distribution of a frame. The TF analysis shows how a frame's properties depend on the signal's TF location and on certain frame parameters View full abstract»

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  • Application of wavelet analysis to automatic frequency control

    Publication Year: 1994, Page(s):484 - 487
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (248 KB)

    The discrete wavelet transform (DWT) being applied to the spectrum analysis algorithm in an automatic frequency control (AFC) feedback loop, the AFC has an intelligent characteristic of “observation and control according to frequency error”, which makes it possible to achieve both fast initial acquisition and accurate tracking. Furthermore, it can make the irreducible frequency error a... View full abstract»

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  • Application of the discrete wavelet transform to identification of questioned documents

    Publication Year: 1994, Page(s):318 - 321
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (224 KB)

    Identification of questioned documents (QDs) is the process of associating documents produced by an unknown writer with labeled archival samples. Here we use the discrete wavelet transform (DWT) to extract characteristics of letters and words of archival database samples, and questioned documents that need to be identified. Using standard clustering techniques, database document characteristics ar... View full abstract»

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  • The instantaneous spectral band

    Publication Year: 1994, Page(s):28 - 31
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (232 KB)

    Shows that while in principle all frequencies existing in a signal are needed to reconstruct it, in actuality only a small band around a central frequency is needed. The central frequency and band are essentially the first and second derivatives of the dynamic signal as defined by Poletti (1993). The authors show theoretically and by example that exact reconstruction of the signal is achieved. The... View full abstract»

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  • Blind and adaptive image restoration in the framework of a multiscale Gabor representation

    Publication Year: 1994, Page(s):306 - 309
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (656 KB)

    We present a blind method for space-variant image restoration, which can be applied to remove degradations due to either additive noise or blurring, but not both simultaneously. Restoration is performed using a multiscale Gabor (1946) representation, which consists of a pyramid of 4×4 Gaborian channels in frequency and orientation plus a zero-frequency residual. The definition of a generic u... View full abstract»

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  • Time-frequency distributions that preserve energy variations

    Publication Year: 1994, Page(s):48 - 51
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (300 KB)

    We present and illustrate the shortcomings of Cohen's (1989) class of bilinear time-frequency distributions (BTFD) in preserving short-time energy variations of the individual frequency components of a multi-component signal. We then define a suitable energy variation property and derive a constraint on the BTFD kernel which is necessary and sufficient for this energy variation property. To satisf... View full abstract»

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  • Block data flow implementation of the 2-D discrete wavelet transform

    Publication Year: 1994, Page(s):294 - 297
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    Implements the 2D discrete wavelet transform (DWT) for real time image processing applications. The algorithms for the 2D wavelet transform can also be viewed as subband filter banks. The authors propose a block data flow architecture (BDFA) for the 2D product separable filter which is used for the DWT. The BDFA uses block data processing and the block data flow paradigm to minimize system managem... View full abstract»

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  • Speech signal analysis with reallocated spectrogram

    Publication Year: 1994, Page(s):640 - 643
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    The limited joint time and frequency resolution of Fourier analysis makes an accurate analysis of speech signals difficult. Fourier analysis offers either good temporal accuracy or good frequency resolution, never both. Many methods have been proposed to overcome this limitation. The results do not show a great improvement in the readability of the representation due to the presence of many compon... View full abstract»

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  • Biomedical applications of time-frequency analysis

    Publication Year: 1994, Page(s):576 - 579
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (300 KB)

    Spectral analysis of heart rate variability (HRV) provides an estimate of sympathetic and parasympathetic influences on heart rate without drugs or other invasive procedures. However, there are many situations where heart rate changes rapidly over time and the control of those changes is of considerable interest. Time-frequency analysis was utilized to expand the concept of spectral analysis of HR... View full abstract»

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  • Scale domain analysis of a bat sonar signal

    Publication Year: 1994, Page(s):373 - 376
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (268 KB)

    Scale domain signal analysis has been developed in response to the need to analyse Doppler-tolerant waveforms or self-similar random signals. Following Cohen's concept of scale representations, this paper introduces the concept of higher-order scale-spectra and investigates advantages and drawbacks of scale domain versus the traditional frequency domain analysis. Several scale-domain methods are a... View full abstract»

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  • 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 (288 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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  • A method for cross-term reduction in the Wigner higher order spectra

    Publication Year: 1994, Page(s):56 - 59
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (248 KB)

    Wigner higher order spectra, in the case of multicomponent signals, are studied. It is shown, that modifying the signal in an appropriate way, before the Wigner higher order spectra application, the terms lying at the positions of instantaneous frequencies of components may be obtained, at the same time avoiding other terms, for any order of spectra. The theory is illustrated on a numerical exampl... View full abstract»

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  • Optimal iterative algorithms in Gabor analysis

    Publication Year: 1994, Page(s):44 - 47
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (340 KB)

    Gabor expansions of discrete signals and images have a wide range of applications in signal analysis and pattern recognition. It is well known that the difficulty in expanding a 1-D or a 2-D signal into a Gabor series is the non-orthogonality of the building blocks, which are time-frequency shifted versions (along some lattice in the TF-plane) of a, given Gabor atom. The theory of frames (Gabor or... View full abstract»

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  • Fault detection and identification using real-time wavelet feature extraction

    Publication Year: 1994, Page(s):217 - 220
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (324 KB)

    Development of real-time fault detection and identification technologies will allow a migration, in the respective theater of operation, from expensive scheduled based maintenance to the more efficient, less costly alternative of condition based maintenance. This paper presents successful initial results applying continuous wavelet transforms coupled with conventional neural networks to the develo... View full abstract»

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  • Multiresolution transient detection

    Publication Year: 1994, Page(s):225 - 228
    Cited by:  Papers (26)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    Designs and studies the performance of a multiresolution-based transient detector. The transients the authors are interested in consist of wide-band, pulse-like, coherent structures in a turbulent flow. To take advantage of the fast pyramidal wavelet algorithm, an important point when processing large amounts of experimental data, the detector makes use of the discrete wavelet transform. The autho... View full abstract»

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  • Matching pursuit of images

    Publication Year: 1994, Page(s):330 - 333
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    A crucial problem in image analysis is to construct efficient low-level representations of an image, providing informations on features such as edges and texture components. An image usually contains very different types of features, which have been successfully modelized by the very redundant family of 2D Gabor functions. However, this model generates representations with a very large size. Inste... View full abstract»

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