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signal INTERCEPTION - A UNIFYING THEORETICAL FRAMEWORK FOR FEATURE DETECTION

IEEE TRANSACTIONS ON COMMUNICATIONS 1988年第8期36卷 897-906页

作者： GARDNER, WA Signal and Image Processing Laboratory Department of Electrical Engineering and Computer Science University of California Davis CA USA

The unifying framework of the spectral-correlation theory of cyclostationary signals is used to present a broad treatment of weak, random signal detection for interception purposes. The relationships among a variety of previously proposed ad hoc detectors, optimum detectors, and newly proposed detectors are established. The spectral-correlation-plane approach to the interception problem is put forth as especially promising for detection, classification, and estimation in particularly difficult environments involving unknown and changing noise levels and interference activity. A fundamental drawback of the popular radiometric methods in such environments is explained.

关键词： Cyclostationary signal Environments Frameworks Unknown interceptions RANDOM signalS feature detections correlation theory

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ENHANCED ANALYSIS-BY-SYNTHESIS WAVEFORM INTERPOLATIVE CODING AT 4 KBPS 6

ENHANCED ANALYSIS-BY-SYNTHESIS WAVEFORM INTERPOLATIVE CODING...

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6th European Conference on Speech Communication and Technology, EUROSPEECH 1999

作者： Gottesman, Oded Gersho, Allen Signal Compression Laboratory Department of Electrical and Computer Engineering University of California Santa BarbaraCA93106 United States

This paper presents an Enhanced analysis-by-synthesis (AbS) Waveform Interpolative (EWI) speech coder at 4 kbps. The system incorporates novel features such as: AbS quantization of the slowly evolving waveform (SEW), AbS vector quantization (VQ) of the dispersion phase, a special pitch search for transitions, and switched-predictive analysis-by-synthesis gain VQ. Subjective quality tests indicate that it exceeds MPEG-4 at 4 kbps and of G.723.1 at 5.3 kbps, and it is slightly better than G.723.1 at 6.3 kbps. © 1999 6th European Conference on Speech Communication and Technology, EUROSPEECH 1999. All rights reserved.

关键词： Vector quantization

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Multimode spectral coding of speech at 2400 bps and below

Multimode spectral coding of speech at 2400 bps and below

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1995 IEEE Workshop on Speech Coding for Telecommunications, SCFT 1995

作者： Das, Amitava Gersho, Allen Signal Compression Laboratory Department of Electrical and Computer Engineering University of California Santa BarbaraCA93106 United States

We present a low bit rate multimode speech coding algorithm which applies a suitable spectral model and a custom quantization scheme to each frame according to the selected mode. For unvoiced speech, the spectrum is characterized by a fixed-dimension spectral shape vector (SSV), while the spectra of 13 different voiced modes are specified by the pitch and a variable dimension SSV. A variable dimension vector quantization technique offers efficient spectral quantization and improves overall speech quality. A variable rate (1.7 kb/s avg. rate;2.4 kb/s max. rate) implementation of the multimode algorithm yields speech quality comparable to the 4.8 kb/s FS 1016 CELP coder and the 4.15 kb/s Inmarsat-MIMBE coder. © 1995 Proceedings - 1995 IEEE Workshop on Speech Coding for Telecommunications: Speech Coding for Interoperable Global Communications, SCFT 1995. All rights reserved.

关键词： Speech coding

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NONSTATIONARY LEARNING CHARACTERISTICS OF THE LMS ALGORITHM

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS 1987年第10期34卷 1199-1207页

作者： GARDNER, WA Signal and Image Processing Laboratory Department of Electrical and Computer Engineering University of California Davis USA

Upper and lower bounding first-order linear recursions for the mean-squared error realized with the LMS algorithm subjected to a sequence of independent nonstationary training vectors are derived. These bounds coincide to give the exact evolution of mean-squared error for the problem of identification of a nonrecursive time-varying system with white-noise excitation. This leads to an exact formula for time-averaged mean-squared error that is used to study optimization of the step-size parameter for minimum time-average misadjustment. New results on dependence of the minimal step size and the minimum misadjustment on the degree of nonstationarity are obtained.

关键词： Least squares approximation System identification Adaptive filters Algorithm design and analysis Vectors Time varying systems Gaussian distribution signal processing Image processing

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ON THE SPECTRUM OF PSEUDO NOISE

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PROCEEDINGS OF THE IEEE 1986年第4期74卷 608-609页

作者： GARDNER, WA CHEN, CK Signal and Image Processing Laboratory Department of Electrical and Computer Engineering University of California Davis CA USA

Although the magnitude of the discrete Fourier transform of a maximal-length shift-register sequence is flat, except for its value at zero frequency, the higher resolution spectral content given by the Fourier-series transform is highly erratic. This little-known fact is described, and its ramifications on fast Fourier transforms of one-digit-extended pseudo noise and zero-padded pseudo noise are explained.

关键词： Discrete Fourier transforms Autocorrelation Frequency Interpolation Fourier transforms White noise Fast Fourier transforms Prediction algorithms Fourier series signal processing

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A LAYER STRIPPING FAST ALGORITHM FOR THE TWO-DIMENSIONAL DIRECT-CURRENT INVERSE RESISTIVITY PROBLEM

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 1987年第5期25卷 558-563页

作者： YAGLE, AE Communications and Signal Processing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

The inverse problem of reconstructing the resistivity of the earth, varying both laterally and with depth, from direct current measurements is considered. The problem is formulated as a multidimensional inverse scattering problem and solved using a layer stripping algorithm. This algorithm recursively reconstructs the resistivity and electrical potential on horizontal planes of increasing depth by downward continuation. This is the first exact solution to the inverse resistivity problem for resistivity varying laterally as well as with depth. The algorithm is an extension of an algorithm proposed by Levy for resistivity varying in one dimension.

关键词： Conductivity Inverse problems signal processing algorithms Earth Electric potential Multidimensional systems Integral equations Current measurement Surface reconstruction Partial differential equations

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Generalized Multi-View Embedding for Visual Recognition and Cross-Modal Retrieval

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IEEE TRANSACTIONS ON CYBERNETICS 2018年第9期48卷 2542-2555页

作者： Cao, Guanqun Iosifidis, Alexandros Chen, Ke Gabbouj, Moncef Laboratory of Signal Processing Tampere University of Technology Tampere Finland Department of Engineering Electrical and Computer Engineering Aarhus University Aarhus Denmark

In this paper, the problem of multi-view embedding from different visual cues and modalities is considered. We propose a unified solution for subspace learning methods using the Rayleigh quotient, which is extensible for multiple views, supervised learning, and nonlinear embeddings. Numerous methods including canonical correlation analysis, partial least square regression, and linear discriminant analysis are studied using specific intrinsic and penalty graphs within the same framework. Nonlinear extensions based on kernels and (deep) neural networks are derived, achieving better performance than the linear ones. Moreover, a novel multi-view modular discriminant analysis is proposed by taking the view difference into consideration. We demonstrate the effectiveness of the proposed multi-view embedding methods on visual object recognition and cross-modal image retrieval, and obtain superior results in both applications compared to related methods.

关键词： Cross-modal retrieval multi-view discriminant embedding multi-view subspace learning visual recognition

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A UNIFYING VIEW OF 2ND-ORDER MEASURES OF QUALITY FOR signal CLASSIFICATION

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IEEE TRANSACTIONS ON COMMUNICATIONS 1980年第6期28卷 807-816页

作者： GARDNER, WA Signal and Image Processing Laboratory Department of Electrical and Computer Engineering University of California Davis CA USA

The major purpose of this paper is to promote interchange between the fields of pattern recognition and communications, in the realm of statistical classification. The general class of second-order measures of quality for statistical classification is defined. The variety of members in this class that have been used by practitioners or proposed by theorists for numerical pattern-classification and signal waveform-classification are compared and contrasted. The several measures that are the most generally applicable are shown to be either equivalent to each other or characterizable in terms of each other, thereby revealing an inherent unity. For example, the ratio of between-class-scatter to within-class-scatter used in pattern recognition and the ratio of signal-energy to noise-energy used in communications are unified through an identification of signal with between-class-scatter and noise with within-class-scatter. Results on equivalences are stated and proved for waveform classification rather than numerical classification in order to complement the extensive literature on the latter, and to emphasize applicability to communications. This entails introduction of a scatter ratio for waveforms. In a companion paper, second-order measures of quality are used as a basis for a general nearestprototype signal-classification methodology; canonical signal features for this methodology are identified, and a general approach for determining appropriate class prototypes is given. These two papers provide an integrated approach to the design of a complete signal classifier, i.e., feature extraction and discriminant-functional design tailored to fit a minimumdistance discrimination rule.

关键词： Pattern classification signal design signal processing Pattern recognition signal to noise ratio Scattering Prototypes Feature extraction Probability Communications Society

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LEARNING CHARACTERISTICS OF STOCHASTIC-GRADIENT-DESCENT ALGORITHMS - A GENERAL STUDY, ANALYSIS, AND CRITIQUE

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signal PROCESSING 1984年第2期6卷 113-133页

作者： GARDNER, WA Signal and Image Processing Laboratory Department of Electrical and Computer Engineering University of California Davis 95616 USA

A comprehensive analysis of the mean-square learning characteristics of stochastic-descent algorithms is presented. The approach is based on the commonly exploited simplifying assumption of stationary independent training vectors. Characteristics analyzed include stability, steady-state misadjustment, initial rate of convergence, optimum step size, and steady-state autocovariance and spectral characteristics of the weight-vector. Effects on these characteristics due to degree of randomness of stochastic gradient, particular data distribution, and data corruption are isolated and analyzed. An objective of the work is to keep the number of simplifying assumptions and approximations to a minimum. Comparison of results with previous more approximate analyses are made. Zusammenfassung Lernkurven von stochastischen Gradienten Algorithmen werden untersucht. Die vereinfachende Annahme von stationären, unabhängigen Trainingsvektoren wird benutzt. Charakteristiken die untersucht werden beinhalten Stabilität, ‘steady state’ Fehlanpassung, Start Konvergenz, optimaler Schritt sowie ‘steady state’ Autokovarianz und spektrale Charakteristik des Gewichtsvektors. Die Effekten auf diese Charakteristiken von dem Zufälligkeitsgrad des stichastischen Gradienten, besonderer Daten Verteilung und Daten Verderbung werden isoliert und analysiert. Ein Zielpunkt dieser Arbeit ist es die Anzahl vereinfachenden Annahmen und Approximationen auf ein minimum zu beschränken. Vergleiche mit Resultaten die von approximativeren Analysen stammen werden gezogen.

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THE ROLE OF SPECTRAL CORRELATION IN DESIGN AND PERFORMANCE ANALYSIS OF SYNCHRONIZERS

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IEEE TRANSACTIONS ON COMMUNICATIONS 1986年第11期34卷 1089-1095页

作者： GARDNER, WA Signal and Image Processing Laboratory Department of Electrical and Computer Engineering University of California Davis CA USA

The popular class of synchronizers that consist of a quadratic nonlinearity followed by a phase-lock loop is investigated, and it is shown that the optimum design of the quadratic transformation is characterized in terms of a spectral correlation function for the signal to be synchronized to. It is also shown that the SNR performance of this quadratic transformation, and the mean-square phase jitter of the phaselock loop are both characterized in terms of spectral correlation functions. The conditions under which the optimum quadratic transformations, for symbol synchronization of BPSK, QPSK, SQPSK, and MSK, and for carrier synchronization of BPSK, reduce to the well-known matched-filter-squarer are identified. In addition, the well-known zeromean-square-phase-jitter condition is generalized from PAM to all synchronizable signals, and is characterized in terms of the spectral correlation function. The low-SNR maximum-likelihood synchronizer for all quadratically synchronizable signals is characterized in terms of a multiplicity of maximum-SNR quadratic spectral-line generators. A closed form implementation in terms of a matched filter, squarer, and symbol-rate-synchronized averager is obtained for BPSK and QPSK signals.

关键词： Performance analysis Frequency synchronization Binary phase shift keying Quadrature phase shift keying Timing Jitter signal generators Matched filters Oscillators Clocks

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