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

1-3 Nov. 1993

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

    Publication Year: 1993
    Request permission for commercial reuse | PDF file iconPDF (29 KB)
    Freely Available from IEEE
  • On separating voiced-speech into its components

    Publication Year: 1993, Page(s):1041 - 1046 vol.2
    Cited by:  Papers (11)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (476 KB)

    We present a new strategy and several algorithms to separate voiced-speech into its natural components. Each component is a generalized spectral line whose instantaneous frequency and amplitude continually evolves in time. The decomposition is achieved by a set of demodulators followed by an array of interconnected feed-forward/feed-back filters. Further analysis of the separated components shows ... View full abstract»

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  • The logarithmic image processing model and its applications

    Publication Year: 1993, Page(s):1047 - 1051 vol.2
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (420 KB)

    This paper presents a summary of operations of the logarithmic image processing (LIP) model and its applications. The LIP model is a mathematical framework which provides a set of generalised version of addition, subtraction, multiplication, convolution and so on, for signal processing. First, we briefly describe the LIP model and point out its distinctive properties for image processing. Then we ... View full abstract»

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  • A unified theory of adaptive locally optimum processing

    Publication Year: 1993, Page(s):1594 - 1597 vol.2
    Cited by:  Papers (8)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    By using the concept of deflection and treating the signal as of known or unknown structure, a unified approach to adaptive locally optimum processing can be developed. This theory brings together processing techniques which have been treated by various authors for application to the detection of either broadband or narrowband signals in undersea surveillance and communications. The theory applies... View full abstract»

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  • Some issues in “blind” array calibration

    Publication Year: 1993, Page(s):1052 - 1056 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (380 KB)

    We consider the problems of direction finding and signal “COPY” with uncalibrated arrays. A number of calibration techniques have been proposed, which attempt to jointly estimate the signal directions or waveforms, and a set of unknown array parameters. We discuss several issues related to the accuracy of these techniques, and the number of signal and array parameters which can be esti... 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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  • A method for adaptive beamforming based on an inverse QR decomposition

    Publication Year: 1993, Page(s):1598 - 1602 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    The inverse QR-based decomposition algorithm is applied to adaptive beamforming. The inverse QR algorithm employs orthogonal rotation operations to update the filter weights thereby preserving the inherent stability properties of the QR method for solving the recursive least squares (RLS) problem. The weight vector for the beamformer is updated in a recursive way while avoiding the highly serial b... View full abstract»

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  • Covert communications employing wavelet technology

    Publication Year: 1993, Page(s):523 - 527 vol.1
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    Atlantic Aerospace and Aware are developing a novel class of spread spectrum system architectures for covert communications based on the theory of wavelets. We describe a class of spread spectrum waveforms that are: (1) highly efficient in their use of signal energy; (2) indistinguishable in appearance from bandpass Gaussian noise; (3) devoid of second and fourth-order cyclostationary features; (4... View full abstract»

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  • Analysis of Booth encoding efficiency in parallel multipliers using compressors for reduction of partial products

    Publication Year: 1993, Page(s):781 - 784 vol.1
    Cited by:  Papers (13)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (276 KB)

    The Booth encoding method is evaluated. Although generally, used in parallel multipliers, the authors show this scheme to be obsolete due to the improvements in bit compression trees. The number of gate levels with and without Booth encoding is compared when 4:2 compressors are used. It was found that a single row of 4:2 compressors reduces the number of partial products to one half which is the e... View full abstract»

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  • Localization of particle sources with detector arrays

    Publication Year: 1993, Page(s):981 - 985 vol.2
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (348 KB)

    Develops methods for localizing particle sources using detector arrays. Projection-based arrays are used and general convex, cubical, and spherical surfaces are investigated. Lower bounds are computed on the mean-square angular error (MSAE) for these arrays. The authors propose an algorithm for direction finding with the cubical array and analyze its MSAE. Potential applications of the proposed me... View full abstract»

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  • Cramer-Rao bounds for two-dimensional deterministic modal analysis

    Publication Year: 1993, Page(s):1152 - 1156 vol.2
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    The purpose of the paper is to develop and explore the Cramer-Rao (CR) bounds for the two-dimensional modal analysis problem. The model employed is deterministic and involves a single snapshot of the data. The bounded parameters include the noise variance, moduli and phases of the signal amplitudes, and the moduli and phases of the 2D modes (poles). The asymptotic behavior of the bounds in the spe... View full abstract»

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  • Additional constraints in the maximum likelihood method to protect against element perturbation

    Publication Year: 1993, Page(s):1057 - 1061 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    The maximum likelihood method (MLM) provides high resolution direction-of-arrival (DOA) performance for an array of sensor elements. Its performance, however, is significantly degraded under conditions of individual element phase errors. Such phase perturbations can be caused by channel phase errors, array element placement errors, and frequency errors. By introducing robust constraints into the M... 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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  • Performance and throughput assessment of the Motorola DSP96002 for real-time FIR filter implementations

    Publication Year: 1993, Page(s):1608 - 1612 vol.2
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (164 KB)

    The execution speed of the Motorola DSP96002 is assessed, by establishing the maximum number of taps of FIR filters that can be implemented in real time. Calculations using manufacturer supplied data yielded a theoretical value of 324 for maximum number of taps for real-time FIR. Real time measurements produced results of 325 for the maximum number of taps. This translates to the execution of an F... View full abstract»

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  • The application of two-dimensional wavelets and filterbanks for convergence enhancement in adaptive arrays for space communications

    Publication Year: 1993, Page(s):518 - 522 vol.1
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (404 KB)

    A linearly constrained wideband adaptive sensor array is described whose adaptive processor is realized with a two-dimensional tree-structured filterbank. The goal is to obtain a fast converging adaptive processor subject to a constraint on the number of adaptive weights and a requirement that the weight updating algorithm exhibit a low computational complexity. It is demonstrated via simulation t... 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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  • Comparison and optimization of digital read channels using actual data

    Publication Year: 1993, Page(s):1474 - 1478 vol.2
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    Various digital equalization and detection schemes have been proposed for disk drive read channels and simulated as a Lorentzian channel [Moon and Carley, 1990]. With the design of linear recording densities greater than two channel bits per half amplitude pulsewidth (PW50), concerns over nonlinear distortions, such as partial erasure, require channel simulation with techniques other than the line... View full abstract»

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  • MUSIC for localization of thunderstorm cells

    Publication Year: 1993, Page(s):986 - 990 vol.2
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    Lightning represents an event detectable optically, electrically, and acoustically, and several systems are already in place to monitor such activity. Unfortunately, such detection of lightning can occur too late, since operations need to be protected in advance of the first lightning strike. Additionally, the bolt itself can traverse several kilometers before striking the ground leaving a large r... 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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  • Properties of quadratic covariance bounds

    Publication Year: 1993, Page(s):1176 - 1180 vol.2
    Cited by:  Papers (6)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    We investigate the properties of quadratic covariance bounds for parametric estimators. The Cramer-Rao, Bhattacharyya (1946), and Barankin (1949) bounds have this quadratic structure and the properties of these bounds are uniquely determined by their respective score functions. We enumerate some characteristics of score functions which generate tight bounds. We also introduce projection operator a... View full abstract»

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  • Effects of multispectral compression on machine exploitation

    Publication Year: 1993, Page(s):1352 - 1356 vol.2
    Cited by:  Papers (8)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (488 KB)

    Conventionally, lossy compression techniques are evaluated in terms of standard performance metrics such as root mean square error and signal-to-noise ratio. It has become increasingly important in remote sensing applications to measure the impact of compression on the utility of multispectral imagery for machine-based exploitation. This paper describes a variety of metrics that measure compressio... View full abstract»

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  • A comparative study of spectral estimation techniques for noisy non-stationary signals with application to EEG data

    Publication Year: 1993, Page(s):1157 - 1161 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (416 KB)

    The paper considers the problem of spectral estimation of noisy non-stationary signals with application to electroencephalogram (EEG) data. Four well known methods for estimating the time-varying spectrum of a non-stationary signal are first reviewed and their performance compared. These methods which work well when the signal-to-noise ratio (SNR) is high, are shown to fail with varying degrees as... View full abstract»

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  • Lossless compression of multispectral images for capture and archiving

    Publication Year: 1993, Page(s):1335 - 1337 vol.2
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (204 KB)

    This preliminary study reports compression gains for the predictive coding of multispectral images by using a context model that includes components from other bands. The interband component better shapes the error distributions for nontrivial compression gains. Although preliminary attempts in this study were unsuccessful, a noncausal study shows that additional gains are possible with a good cau... View full abstract»

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  • Estimation of signal steering vectors in uncalibrated arrays

    Publication Year: 1993, Page(s):1062 - 1066 vol.2
    Cited by:  Papers (5)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (332 KB)

    This paper considers the problem of extracting the signal powers and steering vectors from the signal covariance matrix without the knowledge of array manifold. Under the assumption of narrowband and uncorrelated signals, it is shown that it is necessary and sufficient for the signal powers and steering vectors to satisfy two conditions, termed the signal subspace and orthogonality conditions, in ... View full abstract»

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  • Direction-of-arrival estimation using an ESPRIT array with double invariance

    Publication Year: 1993, Page(s):1381 - 1385 vol.2
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (332 KB)

    We present a new non-iterative method called Weighted Subspace Estimation (WSE) for estimating directions-of-arrival (DOA's) of narrow band plane waves impinging on an ESPRIT array with double invariance. WSE uses the first invariance to get a subspace estimate; the estimates of DOA's are then extracted from the estimated subspace by exploiting the second invariance. Simulations show that, the per... View full abstract»

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