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IEEE Signal Processing Letters

Issue 3 • Date March 1996

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Displaying Results 1 - 11 of 11
  • Combining statistical information in set theoretic estimation

    Publication Year: 1996, Page(s):61 - 62
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (235 KB)

    Statistical information has been used extensively to define feasible solutions in set theoretic signal processing. However, the reliability of the set theoretic estimates resulting from the combination of multiple statistical constraints has thus far not been investigated. We address this question in order to provide a basis for a better use of statistical information in set theoretic estimation p... View full abstract»

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  • The rational filter for image smoothing

    Publication Year: 1996, Page(s):63 - 65
    Cited by:  Papers (45)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (698 KB)

    A nonlinear operator is presented that is able to effectively attenuate the noise that corrupts an image while introducing small distortions on the image details. It is described by a rational function, i.e., by the ratio of two polynomials in the input variables. Notwithstanding its simplicity, this operator proves to be more powerful than conventional methods for many noise distributions. View full abstract»

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  • Word recognition by a parallel-branch subunit model based on misrecognized data in semi-continuous HMM

    Publication Year: 1996, Page(s):66 - 68
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (270 KB)

    We propose a parallel-branch subunit model in semicontinuous HMM for improved initialization and training in word recognition. We obtain the model by adding a new subunit branch based on misrecognized data in training to the previous parallel branches for that subunit. Simulation results show that this proposed model is efficient and gives good recognition performance in word recognition. View full abstract»

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  • FIR filter design for frequency invariant beamformers

    Publication Year: 1996, Page(s):69 - 71
    Cited by:  Papers (73)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (267 KB)

    Two methods of implementing FIR filters for a frequency invariant beamformer are presented. Each of these methods uses a single underlying set of filter coefficients obtained directly from the desired beamformer response. One method uses multirate processing, and the other is based on a single sampling rate. View full abstract»

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  • On bandlimited signals with fractional Fourier transform

    Publication Year: 1996, Page(s):72 - 74
    Cited by:  Papers (126)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (250 KB)

    We study bandlimited signals with fractional Fourier transform (FRFT). We show that if a nonzero signal f is bandlimited with FRFT F/sub /spl alpha// for a certain real /spl alpha/, then it is not bandlimited with FRFT F/sub /spl beta// for any /spl beta/ with /spl beta//spl ne//spl plusmn//spl alpha/+n/spl pi/ for any integer n. This is a generalization of the fact that a nonzero signal can not b... View full abstract»

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  • Fast computation of Gabor functions

    Publication Year: 1996, Page(s):75 - 78
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (341 KB)

    This letter presents a new frame condition for the Gabor expansion that avoids the estimation of frame bounds and the Zak transform and a fast new algorithm to compute the dual frame based on a biorthogonal condition. One of the main contributions of this work is that we can obtain a pair of analysis and synthesis functions that generate a frame and dual-frame pair without computation of frame bou... View full abstract»

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  • Covariant time-frequency representations through unitary equivalence

    Publication Year: 1996, Page(s):79 - 81
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (362 KB)

    We propose a straightforward characterization of all quadratic time-frequency representations covariant to an important class of unitary signal transforms (namely, those having two continuous-valued parameters and an underlying group structure). Thanks to a fundamental theorem from the theory of Lie groups, we can describe these representations simply in terms of unitary transformations of the wel... View full abstract»

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  • A pseudo-Bertrand distribution for time-scale analysis

    Publication Year: 1996, Page(s):82 - 84
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (349 KB)

    Using the pseudo-Wigner time-frequency distribution as a guide, we derive two new time-scale representations: the pseudo-Bertrand and the smoothed pseudo-Bertrand distributions. Unlike the Bertrand distribution, these representations support efficient online operation at the same computational cost as the continuous wavelet transform. Moreover, they take advantage of the affine smoothing inherent ... View full abstract»

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  • Shift-orthogonal wavelet bases using splines

    Publication Year: 1996, Page(s):85 - 88
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (358 KB)

    We present examples of a new type of wavelet basis functions that are orthogonal across shifts but not across scales. The analysis functions are piecewise linear while the synthesis functions are polynomial splines of degree n (odd). The approximation power of these representations is essentially as good as that of the corresponding Battle-Lemarie orthogonal wavelet transform, with the difference ... View full abstract»

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  • A time-frequency distribution concentrated along the instantaneous frequency

    Publication Year: 1996, Page(s):89 - 91
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (333 KB)

    A time-frequency distribution that produces high concentration at the instantaneous frequency for an arbitrary signal is proposed. This distribution may be treated as a variant of the L-Wigner distribution, but it also satisfies unbiased energy condition, time marginal, as well as the frequency marginal in the case of asymptotic signals. The theory presented is illustrated by examples. View full abstract»

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  • Reduced polynomial order linear prediction

    Publication Year: 1996, Page(s):92 - 94
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (347 KB)

    Reduced rank linear predictive frequency and direction-of-arrival (DOA) estimation algorithms use the singular value decomposition (SVD) to produce a noise-cleaned linear prediction vector. These algorithms then root this vector to obtain a subset of roots, whose angles contain the desired frequency or DOA information. The roots closest to the unit circle are deemed to be the "signal roots". The r... View full abstract»

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The IEEE Signal Processing Letters is a monthly, archival publication designed to provide rapid dissemination of original, cutting-edge ideas and timely, significant contributions in signal, image, speech, language and audio processing.

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Meet Our Editors

Editor-in-Chief
Peter Willett
University of Connecticut
Storrs, CT 06269
peter.willett@uconn.edu