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Signals, Systems and Computers, 1991. 1991 Conference Record of the Twenty-Fifth Asilomar Conference on

Date 4-6 Nov. 1991

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  • Conference Record of the Twenty-Fifth Asilomar Conference on Signals, Systems and Computers (Cat. No.91CH3112-0)

    Publication Year: 1991
    Request permission for commercial reuse | PDF file iconPDF (19 KB)
    Freely Available from IEEE
  • The effect of forward-backward data formulation to direction-of-arrival estimation

    Publication Year: 1991, Page(s):923 - 927 vol.2
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    The authors analyze the performance of DOA (direction-of-arrival) estimation using both forward-only and forward-backward data formulations for MUSIC, min-norm, state-space realization, and ESPRIT in a unified fashion. Particular attention is given to the effects of forward-backward data formulation on the statistical performance of the DOA estimation algorithms View full abstract»

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  • Time varying higher order spectra

    Publication Year: 1991, Page(s):393 - 397 vol.1
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    The Wigner-Ville distribution (WVD) is a second-order time-frequency representation in the sense that it is able to give ideal energy concentration for quadratic FM signals, and its expectation value is a second-order time-varying spectrum. The authors present two methods for generalizing the WVD in order to achieve the ideal energy concentration for polynomial frequency (phase) signals. The expec... View full abstract»

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  • A unified formulation for detection using time-frequency and time-scale methods

    Publication Year: 1991, Page(s):637 - 642 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (440 KB)

    A unified theory is developed for the detection of signals in nonwhite noise using time-frequency and time-scale signal transforms. This class includes the cross-Wigner distribution and certain other members of Cohen's class, the Gabor transform, and the wavelet transform. Necessary and sufficient conditions are established such that a signal transform is applicable to the nonwhite noise detection... View full abstract»

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  • A new algorithm for automatic beamforming

    Publication Year: 1991, Page(s):689 - 693 vol.2
    Cited by:  Papers (13)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    A novel blind beamforming scheme for a uniform antenna array is presented to automatically capture a narrowband signal with nonzero kurtoses. It simplifies conventional methods that generally estimate the direction of signal arrival first and then design the beampattern accordingly to retrieve the signal of interest. By maximizing the average kurtosis of the output signal, the blind transformer di... View full abstract»

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  • Optimal dimension reduction for sensor array signal processing

    Publication Year: 1991, Page(s):918 - 922 vol.2
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    The computational complexity for direction-of-arrival estimation using sensor arrays increases very rapidly with the number of sensors in the array. One way to lower the amount of computations is to employ some kind of reduction of the data dimension. This is usually accomplished by employing linear transformations for mapping full-dimension data into a lower-dimensional space. In the present work... View full abstract»

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  • An optimal feature extraction method

    Publication Year: 1991, Page(s):1077 - 1081 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (248 KB)

    The authors present a feature extraction method that can find a minimum set of minimal features for any given set of N binary images (patterns). This method has some similarities to the method of minimizing multiple switching functions. It becomes difficult to apply manually as N becomes large. For large N, a computer implementation of this method is presented. Two examp... View full abstract»

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  • Cramer-Rao bounds for deterministic modal analysis

    Publication Year: 1991, Page(s):388 - 392 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    Cramer-Rao bounds are computed for any unbiased estimator of the mode parameters that characterize an autoregressive moving average impulse response. The bound can be computed for any of the standard parametric descriptions, including autoregressive moving average parameters, poles and residues, and poles and zeros. It is demonstrated that the bounds for any characterization can be obtained from a... View full abstract»

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  • Estimating transfer functions of quadratically nonlinear systems

    Publication Year: 1991, Page(s):632 - 636 vol.1
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    Sinusoidal and white noise input methods have previously been developed for estimating linear or higher order transfer functions of nonlinear systems. The authors describe a colored noise input method, which is based on partitioning the frequency band of interest into subbands, which results in less aliasing in the output and allows for greater precision in the transfer function estimates. With th... View full abstract»

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  • Transform coding of monochrome and color images using trellis coded quantization

    Publication Year: 1991, Page(s):446 - 450 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (384 KB)

    Trellis coded quantization (TCQ) is incorporated into a transform coding structure for encoding monochrome and color images at 1 bit/pixel. Both fixed-rate and entropy-constrained designs are considered. 256-pixel×256-pixel, 8-bit gray-level images and 24-bit color images were encoded using both TCQ-based and scalar-quantizer-based schemes to provide comparisons on the basis of peak-signal-t... View full abstract»

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  • Analysis of the jointly adapting and asynchronously configured V.32 modem implementation

    Publication Year: 1991, Page(s):683 - 688 vol.2
    Cited by:  Patents (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (512 KB)

    The authors describe an implementation of a V.32 modem using new concepts which make it possible to realize a completely digital V.32 modem. The first new concept incorporated is a jointly adapting echo canceler and equalizer where the error signal is derived from the final data decisions. Another new concept used in this implementation is a sample rate convertor algorithm. The receive modem trans... View full abstract»

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  • Algebraic/topological combined strategies for sequential ATPG

    Publication Year: 1991, Page(s):1240 - 1244 vol.2
    Cited by:  Papers (4)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (364 KB)

    The authors describe an algorithm for automatic test pattern generation for sequential integrated circuits that is based on a combination of algebraic and topological techniques. The algebraic concepts of observability and controllability functions have been applied to an innovative version of the sequential D-algorithm working on the combinational part of the network that has been partitioned int... View full abstract»

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  • Beamspace domain bearing estimation for fast target localization using an array of antennas

    Publication Year: 1991, Page(s):913 - 917 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    The authors develop a novel eigen-based bearing estimation scheme for monopulse radar tracking. The eigen-based estimator is chosen in light of its high accuracy. Specifically, the authors derive the MUSIC estimator of the target angle for the amplitude comparison monopulse radar, when given as data, two beams formed by processing the entire set of array signals with two different sets of weights.... View full abstract»

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  • The stochastic segment model for continuous speech recognition

    Publication Year: 1991, Page(s):964 - 968 vol.2
    Cited by:  Papers (3)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    A new direction in speech recognition via statistical methods is to move from frame-based models, such as hidden Markov models, to segment-based models that provide a better framework for modeling the dynamics of the speech production mechanism. The stochastic segment model (SSM) is a joint model for a sequence of observations which provides explicit modeling of time correlation as well as a forma... View full abstract»

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  • Image enhancement and filtering using wavelets

    Publication Year: 1991, Page(s):169 - 174 vol.1
    Cited by:  Papers (5)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (444 KB)

    The authors report on the results of an analysis of the wavelet transform and its use as a tool for image enhancement and filtering in knowledge-based systems. They review the concept of the wavelet transform. A convolution theorem for the wavelet transform and a filter model are described, which uses a wavelet orthonormal basis set. This model is compared to the linear filter model for image enha... View full abstract»

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  • Improving the spatial resolution of real-time radiography images using the maximum entropy method

    Publication Year: 1991, Page(s):1072 - 1076 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (600 KB)

    The authors have evaluated the maximum-entropy method (MEM) as a technique to improve the spatial resolution of real-time radiography images. The point spread function (PSF) of the image intensifier was estimated by differentiating a high-resolution scan made by translating the edge of a lead plate in subpixel increments relative to a single pixel of the CCD (charge coupled device) video camera. T... View full abstract»

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  • Beamspace root-MUSIC for rectangular arrays, circular arrays, and nonredundant linear arrays

    Publication Year: 1991, Page(s):556 - 560 vol.1
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (348 KB)

    Beamspace root-MUSIC is a computationally efficient, beamspace implementation of root-MUSIC developed recently for use in conjunction with a uniformly spaced linear array. Using B real-valued beams having all but B-1 nulls in common, the major computations in beamspace root-MUSIC are a B×B real-valued eigenvalue decomposition and the rooting of a polynomia... View full abstract»

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  • Wideband source modeling and localization: a HOS-based approach

    Publication Year: 1991, Page(s):383 - 387 vol.1
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (372 KB)

    A polyspectra-based solution to the nonparametric multichannel system identification problem is proposed. As an application, the problems of wideband source bearing estimation an identification are considered. Simultaneous detection and parameter estimation of wideband sources arriving at a sensor array are performed using higher-order statistics. Source detection and consistent parameter estimati... View full abstract»

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  • Updating MUSIC and root-MUSIC with the rank-revealing URV decomposition

    Publication Year: 1991, Page(s):277 - 281 vol.1
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (284 KB)

    The authors describe direction-of-arrival (DOA) algorithms that possess the virtues of subspace-based DOA algorithms but are not expensive to compute or difficult to update. The new DOA algorithms are based on a new decomposition, URV decomposition (URVD), which can be updated in O(N2) and serves as an intermediary between QR decomposition and singular value decomposit... View full abstract»

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  • Applications of adaptive time-frequency representations to underwater acoustic signal processing

    Publication Year: 1991, Page(s):1109 - 1113 vol.2
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    The authors describe the application of an adaptive optimal kernel (AOK) time-frequency representation to the processing of underwater acoustic data. The optimal kernel is a signal-dependent radially Gaussian function. Examples are given which demonstrate the effectiveness of the approach for simulated and real sonar data. The simulations indicate that the technique should work well for a larger s... View full abstract»

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  • Implementation of a continuous-state Viterbi algorithm for MAP state estimation

    Publication Year: 1991, Page(s):627 - 631 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (236 KB)

    The authors address the formation of a Viterbi algorithm for maximum a posteriori (MAP) state sequence estimation of a discrete-time continuous-valued Markov process observed in memoryless noise. The usual approach to this problem is to quantize the state space of the Markov process to obtain a standard discrete-state Viterbi algorithm. They introduce an alternate approach based on piecewise linea... View full abstract»

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  • Classification using vector quantization

    Publication Year: 1991, Page(s):439 - 445 vol.1
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (716 KB)

    The authors describe a simple technique for combining vector quantization and low level classification of images. The goal is to classify automatically certain simple features in an image as part of the compression process to enhance their appearance in the reconstructed image. Images in the training sequence are divided into blocks and each block is classified into a particular class by a human o... View full abstract»

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  • Communications equalization using non-linear adaptive networks

    Publication Year: 1991, Page(s):199 - 202 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    The author describes how the equalization process may be viewed as a classification problem and describes how an optimum nonlinear classification strategy is formed. One solution to this classification problem is provided which allows classification on a symbol by symbol basis with an improved bit error rate performance relative to the linear system. A nonlinear structure can provide a near optimu... View full abstract»

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  • Comparison of Class 1 and Class 2 frequency domain matrix and vector estimation filters with adaptive FIR filters

    Publication Year: 1991, Page(s):678 - 682 vol.2
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (292 KB)

    Class 1 and 2 frequency domain block matrix and vector estimation filters are compared with adaptive FIR (finite impulse response) filters based on gradient search algorithms, including Newton, steepest descent, and LMS (least mean square). It is shown that the algorithm of the Class 1 filter considered has the same form as the Wiener-Hopf equation. It is found that the Class 2 estimation filter h... View full abstract»

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  • Parallel error-trapping and error-detection decoding

    Publication Year: 1991, Page(s):35 - 38 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (180 KB)

    The authors present a parallel decoding method for a concatenated outer (nearest the channel) error-correcting code (ECC) and inner (nearest the user) error-detecting code (EDC). This method can be used if (1) both the ECC and EDC are linear codes, (2) the ECC decoder can be implemented as an error-trapping decoder, and (3) the EDC decoder is realized by a polynomial division circuit. The parallel... View full abstract»

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