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

19-22 April 1994

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  • Bootstrap sampling applied to image analysis

    Publication Year: 1994, Page(s):VI/81 - VI/84 vol.6
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (359 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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  • 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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  • 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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  • A new WDF three-port adaptor suitable for floating-point arithmetic and/or DSP implementations

    Publication Year: 1994, Page(s):VI/17 - VI/20 vol.6
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (304 KB)

    A new decomposed version of three-port adaptors for wave digital filters (WDFs) is proposed, which is especially suitable for floating-point arithmetic and for implementation on digital signal processors (DSPs). By using the proposed three-port adaptor, the concept of modified wave digital filters (MWDFs) is appropriately extended to WDFs involving any n-port adaptors (n is integer). The resulting... 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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  • 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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  • 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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  • A bootstrap approach to estimating fractal dimensions

    Publication Year: 1994, Page(s):VI/85 - VI/88 vol.6
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (252 KB)

    This paper outlines a bootstrap approach to estimating the “correlation dimension” of a fractal measure, from a set of observations on that measure. An important example is estimating the dimension of the attractor of a chaotic system from a set of observations on that system. The method reduces the effects of dependence among the observations, is stable to minor variations in the proc... View full abstract»

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  • Multiple bootstrap tests and their application

    Publication Year: 1994, Page(s):VI/69 - VI/72 vol.6
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (320 KB)

    We review bootstrap methods for testing statistical hypotheses. We begin with single hypothesis testing and give an example of its use. We then consider multiple testing based on Holm's step-down procedure and discuss how the bootstrap can incorporate relevant correlation and distributional characteristics. These techniques are applied to tests for zeros of transfer functions of linear systems at ... View full abstract»

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  • A review of signal processing education in Scotland

    Publication Year: 1994, Page(s):VI/29 - VI/32 vol.6
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (344 KB)

    This paper presents a background to the teaching of Signal Processing in Scottish universities, identifies commonality of undergraduate teaching programmes and contents, provides information on the key teaching syllabuses and on the relevant advanced final year options, as well as on postgraduate instructional courses. It also comments on current trends and future directions, and ends by posing a ... View full abstract»

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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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  • Bootstrapping autoregressions with infinite order

    Publication Year: 1994, Page(s):VI/97 - VI100 vol.6
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (216 KB)

    We consider a stationary autoregressive process of infinite order and discuss bootstrap procedures for the autocovariance function and the spectral density. After fitting an autoregressive process of increasing order to the observed data and estimating the parameter of the process we obtain estimated residuals. Now we construct an autoregressive bootstrap process with innovations which are distrib... View full abstract»

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  • Multiple testing for seismic data using bootstrap

    Publication Year: 1994, Page(s):VI/89 - VI/92 vol.6
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (240 KB)

    Investigates the estimation of both the number of waves and of the wave parameters for wavefields in a geophysical application. A parametric method for wave parameter estimation in connection with a multiple test procedure is presented. The distribution of the corresponding test statistic for wideband data is approximated by the central limit theorem and alternatively by a bootstrap procedure. Fin... View full abstract»

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  • Multidimensional reactive elements on curvilinear coordinate systems and their MDWDF discretization

    Publication Year: 1994, Page(s):VI/9 - VI12 vol.6
    Cited by:  Papers (3)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (284 KB)

    Multidimensional Kirchoff circuits have so far been represented in constant coordinate systems. An approach is presented that permits each element of the network to be transformed to a varying coordinate system conserving the properties of the element. The structure of the network itself is not changed. The transformation of the network leads to the introduction of new voltages and currents that i... View full abstract»

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  • Feature representations for monitoring of tool wear

    Publication Year: 1994, Page(s):VI/137 - VI/140 vol.6
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (336 KB)

    We address the general problem of reliable, real-time detection of faults in metal-removal processes in manufacturing. As has long been recognized by skilled machine operators, mechanical and acoustic vibrations can be reliable sources of cues for such monitoring. However, conventional dull-tool monitoring systems, which are generally based on stationary signal processing methods, are inadequate f... 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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  • 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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  • 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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  • 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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  • 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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  • High frequency atmospheric noise mitigation

    Publication Year: 1994, Page(s):VI/101 - VI/104 vol.6
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (356 KB)

    The performance of high frequency (HF) radio communication and radar systems can be limited by noise generated by sources external to the receiving antenna. Below 10 MHz, atmospheric noise generated by worldwide thunderstorm activity tends to be the dominant natural source. We present an empirical analysis of atmospheric noise cancellation achieved by applying an adaptive sidelobe canceller to wid... View full abstract»

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  • Fuzzy logic: issues, contentions and perspectives

    Publication Year: 1994
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (84 KB)

    There has been a rapid growth in the number and variety of applications of fuzzy logic. The successes of fuzzy logic have also generated a skeptical reaction. Most of the criticisms directed at fuzzy logic are rooted in a misunderstanding of what it is and/or a lack of familiarity with it. In many cases, what is not recognized is that the term fuzzy logic (FL) is actually used in two different sen... 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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  • Jackknifing multiple-window spectra

    Publication Year: 1994, Page(s):VI/73 - VI/76 vol.6
    Cited by:  Papers (8)
    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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  • Stability verification of multidimensional Kirchoff circuits by suitable energy functions

    Publication Year: 1994, Page(s):VI/13 - VI/16 vol.6
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (276 KB)

    Multidimensional (MD) Kirchoff circuits (MDKC) are introduced in the theory of MD wave digital filters (MDWDF) in order to develop the so-called reference networks. Since MDWDF principles have also been used for numerical integration of partial differential equations (PDE) having physical relevance, MDKCs have received new significance because they can be used as an equivalent alternative represen... View full abstract»

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