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INTERFERENCE-TOLERANT TIME-DIFFERENCE-OF-ARRIVAL ESTIMATION FOR MODULATED signalS

IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND signal processing 1988年第9期36卷 1385-1395页

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

A method for estimation of the difference in the times of arrival of wavefronts of two separate sensors is introduced. The method, called SPECCORR, exploits the spectral correlation property, called spectral coherence, that essentially all modulated signals exhibit to obtain estimates that are highly tolerant to severely corruptive noise and interference. This tolerance is explained theoretically and demonstrated with simulations.< >

关键词： Interference Time difference of arrival Noise measurement Narrowband Autocorrelation Direction of arrival estimation Antenna measurements Design methodology signal design

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signal INTERCEPTION - A UNIFYING THEORETICAL FRAMEWORK FOR FEATURE DETECTION

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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： computer vision signal processing signal detection Radiometry Detectors Random processes Noise level Interference image processing Satellite broadcasting

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SIMPLIFICATION OF MUSIC AND ESPRIT BY EXPLOITATION OF CYCLOSTATIONARITY

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PROCEEDINGS OF THE IEEE 1988年第7期76卷 845-847页

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

It is shown that for the problem of multiple-source location using antenna arrays, the algorithms MUSIC and ESPRIT can be simplified by use of the property called cyclostationarity, which is exhibited by modulated signals. The advantages of the modified algorithms are reduction in the required number of array elements and associated reduction in the SVD (singular-value-decomposition) computations. The disadvantages are the requirement of either knowing or measuring frequency parameters, such as carrier frequency or baud rate, and the requirement of longer integration time for correlation measurement, as well as the requirement of measuring a different correlation matrix for each signal of interest.< >

关键词： Multiple signal classification Circuits Frequency measurement Scattering parameters Gallium arsenide Sensor arrays Voltage Time measurement Frequency dependence MESFETs

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CORRELATION ESTIMATION AND TIME-SERIES MODELING FOR NONSTATIONARY PROCESSES

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signal processing 1988年第1期15卷 31-41页

作者： GARDNER, WA Signal and Image Processing Laboratory Department of Electrical Engineering and Computer Science University of California Davis CA 95616 U.S.A.

Various types of statistical signal processing require the estimation of time-variant correlation functions and the fitting of time-variant models for nonstationary processes. In this paper, the situations for which nonstationary probabilistic correlation functions can be accurately estimated from a single sample path of a stochastic process are delineated. These include only (i) known form of nonstationarity, (ii) periodic or almost periodic nonstationarity, and (iii) slowly fluctuating nonstationarity. Known methods of estimation for each of these situations are reviewed within the unifying framework of orthogonal series expansions. The fact that estimators based on orthogonal series expansions for nonstationary correlation functions other than (i)–(iii) cannot be guaranteed to be accurate is established. Ramifications for time-variant autoregressive model fitting are discussed. Verschiedene Aufgabenbereiche der signalverarbeitung erfordern die Schätzung zeitvarianter Korrelationsfunktionen und die zeitvariante Modellierung nichtstationärer Prozesse. Im folgenden werden die Situationen dargelegt, für die nicht-stationäre Korrelationsfunktionen aus einem einzigen Repräsentanten eines Prozesses geschätzt werden können. Erfaßt werden können nur Fälle mit (i) bekannter Form der Instationarität, (ii) periodischer oder fast-periodischer Instationarität und (iii) langsam veränderlicher Instationarität. Die bekannten Schätzverfahren für jede dieser Gegebenheiten werden in einem einheitlichen Rahmen, dem der Orthogonalreihen-Entwicklung, zusammengestellt. Die Grenzen der Nutzung von Reihenentwicklungen bei der Schätzung nicht-stationärer Korrelationsfunktionen werden aufgezeigt. Variationsmöglichkeiten für die zeitvariante AR-Modellierung werden diskutiert. De nombreuses operations de traitement du signal requièrent l'estimation de fonctions de corrélation dependent du temps et la construction de modèles variant avec le temps pour les processus nonstationnaires. Dans cet a

关键词： Nonstationary correlation correlation estimation time-series modeling nonstationary time-series

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PHASE SENSITIVITY PROPERTIES OF CASCADED DIGITAL LATTICE ALLPASS FILTERS

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signal processing 1988年第1期15卷 1-21页

作者： REGALIA, PA MITRA, SK Signal Processing Laboratory Department of Electrical and Computer Engineering University of California Santa Barbara CA 93106 U.S.A.

The phase sensitivity with respect to coefficient errors is studied for a class of lattice digital allpass filters. It is shown that corresponding to each lattice parameter there is a set of frequencies for which the phase response remains invariant to an arbitrary perturbation of the parameter. In addition, a simple result of sensitivity “amplification” in lossless two-pair networks is derived, which is used to obtain means and bounds on the sensitivity functions for these lattice structures in term of the lattice parameters. From these results some useful coefficient sensitivity properties are inferred. A practical example is included to better understand the interaction of sensitivity mechanisms in lattice allpass filter realizations, in the context of transfer functions realized as the parallel connection of two allpass filters. Finally, it is shown that the order reduction process intrinsic to the lattice synthesis procedure minimizes the L ∞ norm of the phase sensitivity at each step. Für eine Klasse digitaler Allpaßfilter in Gitterstruktur wird die Empfindlichkeit der Phase gergenüber Koeffizientenfehlern betrachtet. Es wird gezeigt, daß es bezüglich eines jeden Filterparameters gewisse Frequenzpunkte gibt, in denen der Phasengang auch bei beliebiger Parameterverfälschung unverändert bleibt. Darüber hinaus wird in einfacher Form eine “Empfindlichkeits-Verstärkung” in verlustfreien signalfluß-Zweitor-Netzwerken hergeleitet. Sie wird dazu benützt, Mittel- und Grenzwerte für die Empfindlichkeitsfunktionen dieser Gitterstrukturen, ausgedrückt in den Filterparametern, zu gewinnen. Aus diesen Ergebnissen wird auf einige nützliche Eigenschaften der Koeffizientenempfindlichleit geschlossen. Ein praktisches Beispiel schließt sich an; es dient zum besseren Verständnis des Zusammenwirkens von Empfindlichkeitsmechanismen in Gitterstruktur-Allpässen, wie sie zur Realisierung von Übertrangungsfunktionen durch eine Parallel-Anordnung von zwei Allpaßfiltern verwendet werden.

关键词： Digital lattice filters lossless two-pair networks phase sensitivity invariant frequencies

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Connections between three-dimensional inverse scattering and linear least-squares estimation of random fields

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Acta Applicandae Mathematicae 1988年第3期13卷 267-289页

作者： Yagle, Andrew E. Communications and Signal Processing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann Arbor United States

The three-dimensional Schrödinger equation inverse scattering problem with a nonspherically-symmetric potential is related to the filtering problem of computing the linear leastsquares estimate of the three-dimensional random field on the surface of a sphere from noisy observations inside the sphere. The relation consists of associating an estimation problem with the inverse scattering problem, and vice-versa. This association allows equations and quantities for one problem to be given interpretations in terms of the other problem. A new fast algorithm is obtained for the estimation of random fields using this association. The present work is an extension of the connections between estimation and inverse scattering already known to exist for stationary random processes and one-dimensional scattering potentials, and isotropic random fields and radial scattering protentials. © 1988 Kluwer Academic Publishers.

关键词： AMS subject classifications (1980): 35R30, 93E11, 35L20 fast algorithms Inverse scattering linear least-squares estimation random fields

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A computer-BASED SYNTHESIS METHOD OF STRUCTURALLY LBR DIGITAL ALLPASS NETWORKS

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS 1988年第6期35卷 755-760页

作者： SZCZUPAK, J MITRA, SK FADAVIARDEKANI, J Department of Electrical Engineering Pontificia Universidade Catolica do Rio de Janeiro Rio de Janeiro Brazil Department of Electrical and Computer Engineering Signal Processing Laboratory University of California Santa Barbara CA USA AT and T Bell Laboratories Inc. Allentown PA USA

A digital lossless bounded-real (LBR) transfer function, more commonly known as a stable allpass function, maintains the LBR property under multiplier coefficient quantization when implemented by networks that are structurally LBR. A systematic method is outlined for generating all possible such realizations for second-order transfer functions containing a minimum number of multipliers and delays, allowing the designer to take advantage of the flexibility offered by a catalog of such realizations. Illustrative examples are included.< >

关键词： computer networks Network synthesis Transfer functions Frequency Circuit testing Oscillators Analog integrated circuits Electrons Integrated circuit synthesis Quantization

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Low bit-rate LPC speech communications via a new multipulse speech model

Low bit-rate LPC speech communications via a new multipulse ...

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IEEE International Conference on Communications (ICC)

作者： L.D. Paarmann C.A. Magner B.M. McCarthy Signal Processing Laboratory Department of Electrical and Computer Engineering Drexel University Philadelphia PA USA

A speech model with an excitation that is a multipulse sequence with additive white noise is presented. This model, when used in a 4.8-kb/s communication system, has the potential for improved synthetic speech quality. The algorithm is described and convergence for synthetic data of the assumed structure is proved. A method for significantly improved efficiency is presented, based on an algorithm given by M. Korenberg (1985). Initial experimental data that support both the authors' and Korenberg algorithms are given.< >

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signal processing For Ocean Tomography With Moving Ships

Signal Processing For Ocean Tomography With Moving Ships

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Asilomar Conference on signals, Systems & computers

作者： T.G. Birdsall K. Metzger R.C. Spindel Communication and Signal Processing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA Applied Physics Laboratory University of Washington Seattle WA USA

In ocean acoustic tomography, maximal length binary shift- register sequences, m-sequences, are used to modulate acoustic carriers to achieve high average power and good time and Doppler resolution. To date, the underwater transmitters and receivers have been in fixed positions, and signal processing has consisted of demodulation followed by factor inverse filtering. Ocean tomography now is being extended to include the use of moving, ship-towed, transmitters and receivers, where signal processing must account for Doppler time and frequency resealing. This paper describes the signal demodulation and processing methods developed for moving ship tomography and presents illustrative results.

关键词： signal processing Oceans Tomography Marine vehicles Transmitters Spatial resolution signal resolution Filtering Acoustic signal processing Demodulation

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A NEW ALGORITHM FOR ADAPTIVE ARRAYS

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IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND signal processing 1987年第9期35卷 1314-1319页

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

A new deflected stochastic-gradient algorithm for adaptive sensor arrays is introduced. It is shown to have the capability of converging substantially faster than the nondeflected stochastic gradient (LMS) algorithm but slower than the recursive least squares (RLS) algorithm. Because of its amenability to reduction of computational complexity by data quantization, it has the potential for processing digital signals with bandwidths one to two orders of magnitude larger than the bandwidths manageable with the RLS algorithm for sensor arrays containing a number of adjustable weights in the approximate range of 10-50.

关键词： Adaptive arrays Sensor arrays Least squares approximation Resonance light scattering Bandwidth Stochastic processes Least squares methods Computational complexity Quantization signal processing

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