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Acoustics, Speech, and Signal Processing, 1994. ICASSP-94., 1994 IEEE International Conference on

Date 19-22 Apr 1994

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  • Real time implementation of HMM speech recognition for telecommunications applications

    Publication Year: 1994, Page(s):VI/145 - VI/148 vol.6
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (292 KB)

    This paper describes an implementation of connected word recognition using commercially available parallel processing DSPs. The recognition system uses continuous density HMMs for speaker independent recognition over a public switched network. It describes how the computationally intensive functions can be optimised for efficient real time implementation. Results of recognition accuracy are presen... View full abstract»

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  • A statistical model for the simulation of time-varying multipath mobile radio propagation channel

    Publication Year: 1994, Page(s):VI/149 - VI/152 vol.6
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (260 KB)

    We propose a new model for the mobile radio channel which takes into account the channel non-stationarity. It is a statistical model whose parameters are derived from real impulse responses. It is based on modelling the variations of an existing stationary model when moving through small areas within which stationarity can be assumed. The stationary model used was developed in earlier work and con... View full abstract»

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  • Shape estimation and self-noise analysis for towed arrays

    Publication Year: 1994, Page(s):VI/153 - VI/155 vol.6
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (276 KB)

    Towed line arrays of hydrophones are used in the underwater environment to detect weak signals, to resolve closely-spaced contacts and to estimate the bearing and other properties of acoustic sources. The detection performance of a towed array is limited by its self-noise. Towed array data are processed using an adaptive spatial filtering technique implemented in the frequency domain. The resultin... View full abstract»

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  • An overview of multiple-window and quadratic-inverse spectrum estimation methods

    Publication Year: 1994, Page(s):VI/185 - VI/194 vol.6
    Cited by:  Papers (11)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (728 KB)

    Presents examples, history, and a brief review of the theory of multiple-window and quadratic-inverse spectrum estimation methods for mixed harmonizable processes. In addition to the standard uses of making consistent non-parametric auto- and cross-spectrum estimates with jackknife confidence intervals and estimating periodic components in coloured noise, quadratic-inverse theory gives a time-freq... View full abstract»

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  • Location of a dragline bucket in space using machine vision techniques

    Publication Year: 1994, Page(s):VI/161 - VI/164 vol.6
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    Because a dragline bucket's rigging is flexible, its position cannot be inferred from knowledge of rope length and boom position only. Moreover, active devices cannot be placed on the bucket itself to sense position because of the risk of damage. This paper describes a new machine vision system which is being developed to sense bucket position remotely. It is based on a single camera observing the... View full abstract»

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  • Jackknifing multiple-window spectra

    Publication Year: 1994, Page(s):VI/73 - VI/76 vol.6
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    This paper describes some aspects of resampling multiple-window estimates of spectra and related functions in a time-series setting. We show that the jackknife variance of a log spectrum estimate is lower than that obtained by computing the variance directly, and describe a hybrid form with better performance than either. We also give some details on jackknifing line frequency parameters. Finally,... View full abstract»

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  • Generating non-Gaussian random fields for sea surface simulations

    Publication Year: 1994, Page(s):VI/195 - VI/198 vol.6
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    Sea surface simulations are needed to generate realistic glitter in Monte-Carlo testing of automatic target detection in electro-optical imagery of sea scenes. Glitter is determined by the sea surface's height and slope. At present sea surfaces are generally modelled as correlated random fields. Current algorithms for generating large realizations of random fields generally produce correlated Gaus... View full abstract»

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  • The processing of HF skywave radar signals

    Publication Year: 1994, Page(s):VI/165 - VI/168 vol.6
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    This paper presents an overview of a significant and computationally demanding application of signal processing, viz. over-the-horizon radar (OTHR). The Jindalee Operational Radar Network is an integrated network of OTHRs which depend heavily for their performance, in both air and surface mode, on signal processing. It outlines the characteristics of OTHR data that need to be recognised in the des... View full abstract»

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  • STUDIO-monostatic backscatter sounder father of NOSTRADAMUS French O.T.H. radar project-new results

    Publication Year: 1994, Page(s):VI/109 - VI/112 vol.6
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (280 KB)

    In the late 1960s, two new techniques appeared, aimed at reducing the radiated peak power. The first technique was developed in the U.S., based on a bistatic system, using linear FMCW. The second technique was developed in France, a monostatic system using pulse code modulation and alternate transmit-receive periods. This technique is now used in the French OTH radar project NOSTRADAMUS. This pape... View full abstract»

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  • Wave digital filters for the migration of seismic data

    Publication Year: 1994, Page(s):VI/5 - VI/8 vol.6
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    A closed form design method for migration wave digital filters (MWDF) is presented. Migration filters are 2-D fan shaped filters with a prescribed nonlinear phase in the passband. An analytical solution is presented which solves simultaneously the approximation problems for attenuation and phase. The attenuation is approximated in a maximally flat sense in pass- and stopband. The phase of the idea... View full abstract»

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  • Processing of HF signals scattered by artificial ionospheric turbulence using fractal analysis

    Publication Year: 1994, Page(s):VI/169 - VI/171 vol.6
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (184 KB)

    An attempt has been made to apply fractal dimension analysis to HF radio signals scattered from natural and artificially stimulated ionospheric turbulence. Envelopes of the scattered signals in all cases showed a finite fractal dimension as estimated by the correlation integral technique. The signals scattered from artificial turbulence are characterized by a higher correlation dimension, while th... View full abstract»

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  • Noise behaviour in the modified Fourier transform for interferometric data inversion

    Publication Year: 1994, Page(s):VI/157 - VI/160 vol.6
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (224 KB)

    Proposes a modified Fourier transform for the inversion of the visibility function acquired by an unidimensional interferometer observing the surface of the Earth from a low orbit. The inversion of the visibility function by the mean of the usual Fourier transform provides a profile of geometrically distorted brightness temperatures. A modified Fourier transform which takes into account the geomet... View full abstract»

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  • Discrete modelling of plasma equations with ion motion using technique of wave digital filters

    Publication Year: 1994, Page(s):VI/21 - VI/24 vol.6
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (200 KB)

    This paper shows how to solve a system of plasma equations consisting of Euler's and Maxwell's equation systems by using technique of wave digital filters. Since, in plasmas, the electromagnetic effect superposed in addition to the effect of thermal motion in the fluid, both Kirchhoff circuits derived from the equation systems have to be connected each other, which are transformed into well-known ... View full abstract»

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  • The design and development of an undergraduate signal processing laboratory

    Publication Year: 1994, Page(s):VI/41 - VI/44 vol.6
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (400 KB)

    The School of Electrical and Electronic Systems Engineering of Queensland University of Technology (like many other universities around the world) has recognised the importance of complementing the teaching of signal processing with computer based experiments. A laboratory has been developed to provide a “hands-on” approach to the teaching of signal processing techniques. The motivatio... View full abstract»

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  • Engineering education for the 21st century

    Publication Year: 1994, Page(s):VI/33 - VI/36 vol.6
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (252 KB)

    The engineering environment of the 21st century will require new engineers to handle ambiguity and chaos, to understand the design/process/manufacture path for a product, to balance independence and teamwork, and to combine the techno-scientific base with a societal context. This paper summarizes some of the specific activities and experiments currently underway at universities in the United State... View full abstract»

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  • An update on the CMU virtual laboratory

    Publication Year: 1994, Page(s):VI/53 - VI/56 vol.6
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (380 KB)

    The ECE department at CMU has implemented a new integrated curriculum which emphasizes learning in the context of applications. Development of a new laboratory paradigm has been critical to maximize conceptual learning while minimizing student busy work and faculty laboratory maintenance. The resulting virtual laboratory paradigm and redesign of the fundamental signals and systems course was the s... View full abstract»

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  • On model identification for distortion correction of OTH radar signals

    Publication Year: 1994, Page(s):VI/129 - VI/132 vol.6
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (252 KB)

    When HF skywave radars are employed for missions where high Doppler resolution is required, such as ship detection or remote sensing of the sea surface, nonstationarity of the ionospheric propagation channel within the coherent integration period often occurs to the extent that the Doppler spectrum is corrupted and the mission is unsuccessful. To overcome this problem, various signal processing te... View full abstract»

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  • Bootstrap sampling applied to image analysis

    Publication Year: 1994, Page(s):VI/81 - VI/84 vol.6
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    We present the bootstrap sampling techniques applied to some pattern recognition algorithms. Two important procedures in image analysis are tested: a statistical segmentation based on expectation-maximisation (EM) family algorithms and two methods of invariant features extraction for gray level images. In the first case, the results we obtain show that the bootstrap sample selection method gives b... View full abstract»

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  • Multidimensional wave-digital principles: from filtering to numerical integration

    Publication Year: 1994, Page(s):VI/173 - VI/181 vol.6
    Cited by:  Papers (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (868 KB)

    Wave-digital principles, originally developed for one-dimensional filtering purposes, have later been extended to multidimensional filtering applications and have been shown to be applicable also to numerical integration of physically relevant ordinary and partial (thus multidimensional) differential equations of linear and nonlinear type. They are based on physical concepts such as Kirchhoff circ... View full abstract»

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  • Jackknifed multiple-window spectra and coherence applied to seismic data

    Publication Year: 1994, Page(s):VI/93 - VI/96 vol.6
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (268 KB)

    Examines the variance of power spectra and magnitude squared coherences determined from local earthquake seismograms recorded synchronously on a small aperture seismic array. The multiple taper algorithm is used to calculate the spectra and coherences. Variances of these estimates are calculated with the jackknife technique, after transforming to a more normal distribution, and are compared with e... View full abstract»

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  • Adaptive wave digital fan filters

    Publication Year: 1994, Page(s):VI/25 - VI/28 vol.6
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    Adaptive two-dimensional (2-D) fan filters based on least mean square algorithm and 2-D wave digital filter structure are presented. The weight updating equations as well as the equations for computing the gradient components of signals in two-dimensional wave digital filter adaptors are derived and specifically applied to wave digital quadrant and narrowband fan filters. Computer simulations are ... View full abstract»

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  • Computing and signal processing: an experimental multidisciplinary course

    Publication Year: 1994, Page(s):VI/45 - VI/48 vol.6
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    In the Fall of 1993 at Berkeley we offered an experimental graduate course that focused on languages for modeling and design of signal processing systems. A major motivation for the course is our Ptolemy project, in which we are experimenting with models of computation and design methodology for signal processing systems. The applicable theory of computation primarily concerns stream datatypes and... View full abstract»

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  • Space and time statistical data processing in HF ionospheric sounding

    Publication Year: 1994, Page(s):VI/121 - VI/124 vol.6
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (176 KB)

    The paper describes spectral and correlation processing of the HF radio signals scattered by small scale ionospheric inhomogeneities (5 to 50 m in size). The measurements at frequencies above MUF were performed on single-hop midlatitude propagation paths. The probing signals from suitable broadcasting stations were received with small size dipole antennas and a highly directional large array, and ... View full abstract»

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  • The Signal Processing Information Base project: the present and the future

    Publication Year: 1994, Page(s):VI/37 - VI/40 vol.6
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (324 KB)

    The Signal Processing Information Base (SPIB) represents an attempt by the Signal Processing Society to make generally available information-data, papers, software, and bibliographies-necessary for state-of-the-art research and development. Access to the repository relies on the Internet, which makes SPIB available to students, researchers, and developers around the world. The variety of informati... View full abstract»

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  • DSP and communication engineering education with graphical block diagram simulation tools

    Publication Year: 1994, Page(s):VI/57 - VI/60 vol.6
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    Graphical block diagram simulation tools with highly interactive plotting and visualization capabilities can accelerate and greatly improve DSP and communications education. In this paper, we present several projects given in graduate and senior level undergraduate courses in DSP and communications which use the graphical simulation tool Capsim, and emphasize the importance of true multi-rate sign... View full abstract»

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