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Signals, Systems and Computers, 1993. 1993 Conference Record of The Twenty-Seventh Asilomar Conference on

Date 1-3 Nov. 1993

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  • Proceedings of 27th Asilomar Conference on Signals, Systems and Computers

    Publication Year: 1993
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    Freely Available from IEEE
  • Conditions for unambiguous source location using polarization diverse arrays

    Publication Year: 1993, Page(s):1365 - 1369 vol.2
    Cited by:  Papers (17)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (404 KB)

    As array processing becomes more mature, interest has grown in the use of polarization diverse arrays for both direction finding (DF) and signal copy. However, little has been written on the maximum number of source bearings which can be unambiguously estimated with a polarization diverse array of N antennas. This paper gives necessary conditions for the number of antennas needed to unambiguously ... View full abstract»

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  • Underwater acoustic field extrapolation using vertical reference arrays

    Publication Year: 1993, Page(s):154 - 158 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    Conventional methods for predicting acoustic propagation through a region of ocean require detailed knowledge of the environment. A method that acoustically “calibrates” the medium through the use of vertical transmit and receive arrays is discussed. By combining (via a generalized form of Huygens' principle) the measured calibration data with field estimates based on limited local env... View full abstract»

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  • On blind system identification from its output autocorrelation

    Publication Year: 1993, Page(s):731 - 735 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (232 KB)

    When the input to a linear time-invariant system is a sequence of equispaced Dirac delta functions with IID. random amplitudes, it has been shown that a time-limited system can be uniquely identified from its output autocorrelation by making use of the cyclostationarity of the output [Tong et al. 1991]. The present authors show that a bandlimited system, however, can not be uniquely identified fro... View full abstract»

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  • Segmenting color images using Markov random field models

    Publication Year: 1993, Page(s):553 - 557 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (328 KB)

    We use Markov random field models for color images in conjunction with a three phase segmentation algorithm based on region splitting, conservative merging, and agglomerative clustering. At each step, the agglomerative clustering phase maximizes a global performance functional based on the conditional pseudo-likelihood of the image. A test for stopping the clustering is applied based on rapid chan... View full abstract»

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  • Block-based attractor coding: potential and comparison to vector quantization

    Publication Year: 1993, Page(s):1504 - 1508 vol.2
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (384 KB)

    The paper presents a simple fractal or attractor coder model that has a very fast decoding algorithm and lends itself to comparisons with vector quantization (VQ) of the mean-gain-shape (MGSVQ) type. In fractal theory the transmission of the codebook is somewhat concealed. In our simple model the codebook is explicitly transmitted although with a double role. The main difference between MGSVQ and ... View full abstract»

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  • Verification of handwritten signature images by multiresolution wavelet analysis

    Publication Year: 1993, Page(s):6 - 10 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (404 KB)

    We took a multi-resolution approach to the signature verification problem. The top-level representation of signature images was the global geometric features including the size and slant angle. A multiresolution representation of signature images was obtained using the wavelet transformation. We evaluated the feature representation at different scales and developed schemes to use this multi-resolu... View full abstract»

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  • GMLOS: a new robust nonlinear filter for image processing applications

    Publication Year: 1993, Page(s):871 - 875 vol.2
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (416 KB)

    The restoration and enhancement of degraded images are of fundamental importance in image processing applications. The authors introduce a new robust nonlinear filter (single and multistage) based on generalized maximum likelihood reasoning and order statistics (GMLOS). This new filter is not only capable of attenuating the noise and presenting the derails, but also has the ability to sharpen the ... View full abstract»

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  • Implementation of a 5.0 kb/s. coder for vehicular applications. II. Acoustic echo and noise canceller

    Publication Year: 1993, Page(s):776 - 780 vol.1
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (340 KB)

    Presents the results of research on the real-time implementation of a digital echo and vehicular noise canceller on a TMS320C50/51 platform to comply with the ongoing efforts on half-rate coder implementation at various industrial and academic research and development centers. The proposed echo and noise cancellers are expected to be interfaced with a speech coding system for use in an automobile ... View full abstract»

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  • A direction-finding algorithm for lens-based antenna systems

    Publication Year: 1993, Page(s):1370 - 1375 vol.2
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (380 KB)

    In this paper, we describe a high-resolution direction-of-arrival (DOA) estimation algorithm for the enhancement of a lens-based antenna system. In such a system, the antenna array is followed by an electromagnetic lens and a bank of power detectors (crystal video receivers). This system can handle sources over a large bandwidth and can detect pulsed sources that exist for short periods of time. T... View full abstract»

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  • Numerical aspects of temperature profile reconstruction using acoustic tomography in RTP

    Publication Year: 1993, Page(s):149 - 153 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (380 KB)

    Precise wafer temperature control is crucial to the viability of the emerging technology of rapid thermal processing (RTP) for semiconductor manufacturing. The authors examine the problem of accurate noninvasive measurement of wafer temperature, which is required for precise temperature control. The paper extends the work of Khuri-Yakub et al. (1993) on acoustic techniques for noninvasive wafer te... View full abstract»

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  • Implementation of a 5.0 kb/s. coder for vehicular applications. I. Finite state VQ CELP coder

    Publication Year: 1993, Page(s):726 - 730 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (328 KB)

    In the present paper and its companion, the authors present the results of research on the real-time implementation of a speech coding system for use in an automobile environment subject to both road engine, and wind noises and acoustic echos. The authors emphasize a TMS320C30-based implementation of an finite-state VQ CELP coder operating at 5,000 bits per second View full abstract»

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  • Pipelined implementation of b-splines and beta-splines for computer graphics and visualization applications

    Publication Year: 1993, Page(s):548 - 552 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (340 KB)

    Beta-splines used in visualization techniques differ from b-splines in that they are constructed using geometric continuity constraints instead of parametric derivative constraints. They are piecewise polynomial interpolating functions. We show how to exactly compute the samples of these functions from a sparse set of points. This computation uses only summations, and no multiplications after init... View full abstract»

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  • Efficient organization of large ship radar databases using wavelets and structured vector quantization

    Publication Year: 1993, Page(s):491 - 498 vol.1
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (644 KB)

    We investigate the problem of efficient representations of large databases of pulsed radar returns from naval vessels in order to economize memory and minimize search time. We use synthetic radar returns from ships as the experimental data. The results extend to real ISAR returns. We develop a novel algorithm for organizing the database, which utilizes a multiresolution wavelet representation work... View full abstract»

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  • Multiple model encoding of images

    Publication Year: 1993, Page(s):1509 - 1513 vol.2
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    Images are fundamentally inhomogeneous and nonlinear, yet most coding has been based on homogeneous processing using linear techniques. This paper describes our progress to develop a framework for nonlinear, multiscale, inhomogeneous coding, and describe the particular research efforts within the MIT Perceptual Computing Section that are beginning to fill out this framework View full abstract»

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  • Phase transitions and multi-scale Markov random fields: application to texture synthesis

    Publication Year: 1993, Page(s):1 - 5 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    The increased use of Markov random field (MRF) models in image processing applications makes it important to understand their behavior under scale transformations. In this work, a multi-scale MRF is viewed as a parameter trajectory on a surface whose topological structure depends on the coarsening scheme employed in the scale transformation. These transformations are based on renormalization theor... View full abstract»

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  • Subband image coding with optimal intra- and inter-band subband quantization

    Publication Year: 1993, Page(s):876 - 880 vol.2
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (452 KB)

    Significant progress has been made in the theory and design of analysis/synthesis filter banks and in the independent encoding and decoding subsystems. However, by comparison, little attention has been given to the optimal design of subband quantizers in the sense of minimizing the overall average distortion subject to a constraint on the output rate of the subband system. In the paper, necessary ... View full abstract»

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  • A deterministic approach to blind equalization

    Publication Year: 1993, Page(s):751 - 755 vol.1
    Cited by:  Papers (54)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (340 KB)

    Conventional blind channel identification algorithms are based on channel outputs and the known probabilistic model of a channel input. In practical applications, however, the input statistical model may not be known, or there may not be sufficient data to obtain accurate enough estimates of certain statistics. In this paper, we consider the system input to be an unknown deterministic signal and s... View full abstract»

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  • A completely pipelined regular array processor implementation of the RITE algorithm

    Publication Year: 1993, Page(s):771 - 775 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    The paper presents a completely pipelined regular array processor implementation of a direction of arrival estimator. The estimator employs the recursive/iterative eigenspace decomposition (RITE) of a hermitian Toeplitz spatial correlation matrix. In addition to the recursive and iterative nature of the algorithm, various dependencies are strongly connected. The eigenvalue computations are based o... View full abstract»

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  • Direction finding with interpolated mode

    Publication Year: 1993, Page(s):1376 - 1380 vol.2
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    We present a generalization of the MODE direction finding algorithm, using the interpolated array approach. The proposed algorithm is statistically efficient for uncorrelated, correlated and even coherent sources, and requires only a modest amount of computations. The use of array interpolation makes it possible to easily incorporate calibration data into the estimation procedure. The performance ... View full abstract»

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  • High-resolution imaging technique for aperture-array dynamic sensing systems

    Publication Year: 1993, Page(s):144 - 148 vol.1
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (284 KB)

    Much of the research in imaging technology has been limited to creating three-dimensional images of static source distributions, by employing one of several common coherent illumination signals. The field of computer vision has been concerned more with dynamic source distributions, but has focused almost exclusively on the use of incoherent illumination in the infrared or visible ranges. The use o... View full abstract»

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  • Evaluation of a model based data fusion algorithm with multi-mode OTHR data

    Publication Year: 1993, Page(s):300 - 304 vol.1
    Cited by:  Papers (4)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (432 KB)

    Australia's over-the-horizon-radar system, the Jindalee Operational Radar Network, is due to be commissioned in 1997. When operating it is possible that associated tracks of one aircraft may arise from multiple propagation paths and multiple radars. Errors in estimating the propagation path result in errors in estimating the position of the aircraft. Also, the structure of the ionosphere typically... View full abstract»

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  • Super resolution radar imagery based on 2D linear extension

    Publication Year: 1993, Page(s):598 - 602 vol.1
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    This paper presents a procedure to process two dimensional RCS data to obtain super-resolution radar imagery. The data is collected by an inverse synthetic aperture radar (ISAR) in the X-band. The procedure is called two dimensional (2D) linear extension. It is used to enhance the resolution of ISAR images beyond the classical Rayleigh limit. For comparison purpose, the procedure has been implemen... View full abstract»

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  • Spherically invariant random processes for modeling non-Gaussian radar clutter

    Publication Year: 1993, Page(s):1106 - 1110 vol.2
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (468 KB)

    This investigation is motivated by the problem of modeling correlated non-Gaussian radar clutter. Experimental research has confirmed that radar clutter can have an extended tail under certain conditions. Since the Gaussian model fails to predict the extended tail behavior, non-Gaussian probability density functions (PDF) have been used for the first order PDF of the clutter. Usually, radars proce... View full abstract»

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  • An efficient non-iterative method for estimating the angles of arrival of known signals

    Publication Year: 1993, Page(s):1396 - 1400 vol.2
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    The vast majority of existing high resolution angle of arrival (AOA) estimators are designed for the case of completely unknown signal waveforms. However, in many applications, such as mobile communications, the receiver has access to the structure of the incoming signals. By exploiting this extra information, a considerable improvement in estimation accuracy and/or computational complexity can be... View full abstract»

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