1996 IEEE International Conference on Acoustics, Speech, and Signal Processing Conference Proceedings

9-9 May 1996

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  • IER clutter reduction in shallow water

    Publication Year: 1996, Page(s):3041 - 3044 vol. 6
    Cited by:  Papers (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (440 KB)

    One of the most difficult challenges in shallow water active sonar processing is false alarm rate reduction via active classification. The goal of active classification is to remove as much clutter as possible while maintaining an acceptable P/sub d/ performance. Clutter in this context refers to any nontarget, threshold crossing cluster events. We present a novel approach to clutter reduction in ... View full abstract»

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  • A modified Eckart post-beamformer filter for improved detection using broadband features

    Publication Year: 1996, Page(s):3045 - 3048 vol. 6
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (298 KB)

    The problem of signal detection using passive sonar signal processing methods to extract features is addressed. We propose a modified Eckart post-beamformer filter to obtain better estimates of the signal and in particular the broadband component of the signal. The physical processes motivating the study are broadband features which are usually ignored in conventional narrowband detection and clas... View full abstract»

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  • Feature extraction and sufficient statistics in detection and classification

    Publication Year: 1996, Page(s):3049 - 3052 vol. 6
    Cited by:  Papers (6)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (436 KB)

    The effectiveness of sufficient statistics as features in the detection/classification process is studied. The concept of a sufficient statistic is reviewed and an empirical method of developing an 'apparent' sufficient statistic from training data is offered. Examples of the performance enhancement achieved when using such statistics on real world data in both linear and neural network classifier... View full abstract»

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  • Gerschgorin radii based source number detection for closely spaced signals

    Publication Year: 1996, Page(s):3053 - 3056 vol. 6
    Cited by:  Papers (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (367 KB)

    We first analyze the resolution performance of the Gerschgorin radii based source number detector proposed by Wu, Yang and Chen (see IEEE Trans. SP, vol.43, no.6, p.1325-33, 1995) for independent closely-spaced plane waves. Based upon the analysis, we can easily verify the resolution threshold of the Gerschgorin radii based algorithm. For improvement of the detection performance, we then further p... View full abstract»

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  • A wavelet transform frequency classifier for stochastic transient signals

    Publication Year: 1996, Page(s):3057 - 3060 vol. 6
    Cited by:  Papers (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (468 KB)

    The paper presents a wavelet transform based frequency classifier for stochastic bandpass transient signals. Using compactly supported bases of wavelets, continuous nonstationary bandpass processes can be described by reduced dimension discrete time signal representations. We develop an optimization procedure to adapt both the sampling frequency and the discrete time wavelet filters to the continu... View full abstract»

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  • Classification with a combined information test

    Publication Year: 1996, Page(s):3061 - 3064 vol. 6
    Cited by:  Papers (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (287 KB)

    We introduce a discrete model for classifying a target that combines the information in training and test data to infer about the true symbol probabilities. Two tests are derived given that the symbols are distributed as a multinomial. The robustness of these tests lies in their ability to effectively use all of the information in the training and test data before making a classification decision.... View full abstract»

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  • 3-D MUSIC with polynomial rooting for near-field source localization

    Publication Year: 1996, Page(s):3065 - 3068 vol. 6
    Cited by:  Papers (13)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (298 KB)

    The bearing, elevation, and range estimation of near-field narrow-band sources from data observed across an array of sensors is considered. For high-resolution source localization, the multiple signal classification (MUSIC) algorithm is modified and extended to its 3-D version by accounting for the spherical curvature and spreading factor in the array manifold. However, the simultaneous estimation... View full abstract»

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  • Closed-form elliptic location with an arbitrary array topology

    Publication Year: 1996, Page(s):3069 - 3072 vol. 6
    Cited by:  Papers (10)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (375 KB)

    An efficient noniterative algorithm for active localization of objects is developed. It is based on intersecting elliptic curves defined by uncertain range-sum measurements between a signal source, the objects, and a number of arbitrarily located receivers. Measurement errors are modelled as being unknown but bounded in amplitude by a closed convex set. Based on this set-theoretic uncertainty mode... View full abstract»

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  • Source localisation with recurrent neural networks

    Publication Year: 1996, Page(s):3073 - 3076 vol. 6
    Cited by:  Papers (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    We address the far-field source localisation problem. A new neuromimetic approach is presented. Instead of considering time as a second dimension of the input space, time is implicitly encoded in the structure of a recurrent neural network. This allows us to process temporal data such as the temporal propagation delays between the sensors of a linear array. Recurrent neural networks are encompasse... View full abstract»

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  • A test for detection of local modeling mismatches in shallow water

    Publication Year: 1996, Page(s):3077 - 3080 vol. 6
    Cited by:  Papers (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    This paper presents a new, non-parametric test for detecting modeling mismatches in a propagation medium, as shallow water. The test is based on the fact that if there are no model uncertainties, the corresponding modal spectrum of the received signal is strictly band-limited to an a-priori known band. Any mismatches in the assumed model cause the modal spectrum out of this band to be non-zero. To... View full abstract»

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  • Broadband matched field processing using robust prewhitening and multiple window techniques

    Publication Year: 1996, Page(s):3081 - 3084 vol. 6
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (398 KB)

    The estimation of source and environmental parameters for stationary broadband wave propagation in an unknown shallow ocean is considered. We apply an approximate maximum-likelihood technique (AMLE) in the frequency domain after cleaning the observations from outliers using robust prewhitening. This method is compared with the previously used multitaper techniques. Environmental noise in data obta... View full abstract»

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  • Focalization in the Gulf of Mexico

    Publication Year: 1996, Page(s):3085 - 3088 vol. 6
    Cited by:  Papers (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (363 KB)

    Matched-field processing (MFP) has been an active area of research in the last decade for estimating the location of a sound source and parameters related to the ocean channel. MFP yields estimates of the unknown parameters by matching the true received acoustic field to the theoretically predicted field calculated for sets of likely values for the unknown parameters. Successful demonstrations of ... View full abstract»

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  • Robust maximum likelihood source localization by exploiting predictable acoustic modes

    Publication Year: 1996, Page(s):3089 - 3092 vol. 6
    Cited by:  Papers (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (611 KB)

    This paper presents a robust maximum-likelihood estimator for matched-field source localization in the presence of uncertainties in the ocean environment. The method is based on a decomposition of the field into predictable and unpredictable subspaces of the acoustic normal mode representation. The performance of the method is evaluated and compared to other matched-field methods using simulations... View full abstract»

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  • A sub-space method for high resolution bathymetry

    Publication Year: 1996, Page(s):3093 - 3096 vol. 6
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    To increase the accuracy and the rate of coverage of a given area in shallow coastal waters, light-detection and ranging (lidar) airborne laser ranging systems have been introduced. A new formulation for ocean-depth measurement using the frequency-domain approach as proposed. This technique uses a high-resolution eigensubspace method to estimate the ocean-depth from backscattered noisy data. The p... View full abstract»

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  • Multiresolution stochastic models for the efficient solution of large-scale space-time estimation problems

    Publication Year: 1996, Page(s):3097 - 3100 vol. 6
    Cited by:  Papers (5)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (578 KB)

    The successful application of a previously developed tree-based multiscale estimation framework to large-scale static estimation problems has proven the statistical flexibility and the computational efficiency of the framework. However, the estimation of processes evolving in time remains a considerable challenge. We address this challenge by investigating multiscale models for the steady-state es... View full abstract»

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  • A comparison of two techniques for detecting seizure in newborn EEG data

    Publication Year: 1996, Page(s):3101 - 3104 vol. 6
    Cited by:  Papers (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (362 KB)

    This paper considers the problem of automatic classification of newborn electroencephalogram (EEG) data in order to diagnose for seizure. It is shown that good detection performance of seizure EEG is possible using a methodology based on a model for the generation of the EEG. This model is derived from the histology and biophysics of a localised portion of the brain and is thus physically motivate... View full abstract»

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  • Classification of radar returns using Wigner-Ville distribution

    Publication Year: 1996, Page(s):3105 - 3108 vol. 6
    Cited by:  Papers (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (350 KB)

    This paper attempts to analyze and classify the radar returns from a simulated ground based radar using Wigner-Ville distribution (WVD). Stochastic modeling methods like AR and ARMA have earlier been applied for the classification problem. However they suffer from inaccuracies such as showing inexact spectral widths, which is a prime factor to distinguish weather returns from birds, non-adaptabili... View full abstract»

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  • On the design of a transversal filter bank for parallel processing multiple image lines in real-time acoustic imaging

    Publication Year: 1996, Page(s):3109 - 3112 vol. 6
    Cited by:  Papers (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (446 KB)

    We present a new method for designing a transversal filter bank for parallel processing echo data in real-time active acoustic imaging. The method is based on a discretized linear spatio-temporal formulation of an imaging system which uses transmitter arrays with coded-excitation. The filter coefficients are derived from a pseudo-inverse operator which not only decouples echoes from different imag... View full abstract»

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  • A minimax optimization approach to sidelobe suppression filter design

    Publication Year: 1996, Page(s):3113 - 3116 vol. 6
    Cited by:  Papers (3)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (359 KB)

    A sidelobe suppression filter is designed to operate simultaneously with a matched filter. For the purpose of the design, a filter is canonically decomposed into two orthogonal components. One is the conventional matched filter, the other is the sidelobe suppression filter. The minimax optimization technique is utilized to determine the optimal filter weights to minimize the peak sidelobe level of... View full abstract»

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  • An EM algorithm for multisensor TDOA/DD estimation in a multipath propagation environment

    Publication Year: 1996, Page(s):3117 - 3120 vol. 6
    Cited by:  Papers (2)  |  Patents (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (376 KB)

    The problem of estimating time-difference-of-arrival (TDOA) and differential Doppler (DD) in a multipath environment is addressed. Correlated multipath interference has degenerative effects on the cross-ambiguity function which is the conventional joint TDOA/DD estimator. A new method, previously proposed for multisensor/multipath TDOA estimation, is extended to accommodate linearly-varying time d... View full abstract»

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  • Adaptive realization of a maximum likelihood time delay estimator

    Publication Year: 1996, Page(s):3121 - 3124 vol. 6
    Cited by:  Papers (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (391 KB)

    This paper presents an adaptive maximum likelihood method for estimating the time difference of arrival of a source signal at two spatially separate sensors. It is well-known that the maximum likelihood technique achieves the Cramer-Rao lower bound for time delay estimation error for certain signal conditions. The /spl alpha/-/spl beta/ tracker is a heuristic mechanism that is heavily used in targ... View full abstract»

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  • Robust time delay estimation using lower-order statistics

    Publication Year: 1996, Page(s):3125 - 3128 vol. 6
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (398 KB)

    New methods for time delay and frequency delay estimation are introduced based on the theory of alpha-stable distributions. It is shown that these methods are robust for both Gaussian and non-Gaussian impulsive noise environments. Their improved performance is clearly demonstrated with both computer generated data and actual radar clutter data. View full abstract»

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  • New perspectives for maximum-likelihood parameter and time delay estimation using two channels

    Publication Year: 1996, Page(s):3129 - 3132 vol. 6
    Cited by:  Papers (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (336 KB)

    This paper introduces a new realization for maximum likelihood parameter and time-delay estimation using two channels. We obtain the result by using coupled Karhunen-Loeve expansions to derive the likelihood function. The new realization illuminates the analytical relationship between maximum likelihood time-delay estimation and other methods. Experimental results that support the theoretical find... View full abstract»

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  • Iterative maximum-likelihood/cross-correlation algorithm for reflection and pulse TOA estimation

    Publication Year: 1996, Page(s):3133 - 3136 vol. 6
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (349 KB)

    An iterative method that combines a parametric channel model with the maximum likelihood and cross-correlation estimation techniques has been developed to estimate the reflection, creeping wave, and times of arrival (TOAs) from an echo (backscatter) emanating from a rigid acoustic sphere. The modelled echo is assumed to be more complex than a linear combination of delayed and scaled versions of th... View full abstract»

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  • The issue of phase in specular multipath parameter estimation

    Publication Year: 1996, Page(s):3137 - 3140 vol. 6
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (373 KB)

    Phase differences between multipath reflections come from properties inherent to every multipath channel and they produce problems in previously introduced multipath parameter (delay, Doppler shift and amplitude) estimators. Ways of overcoming these problems are suggested, and the phase is considered as a parameter to be estimated, as well. Phase estimates are important if multipath components are... View full abstract»

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