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International Conference on Acoustics, Speech, and signal Processing (ICASSP)

作者： V.S. Somayazulu S.K. Mitra J.J. Shynk Signal & Image Processing Laboratory Department of Electrical & Computer Engineering University of California Santa Barbara CA USA

A novel structure for multirate adaptive filtering with lower computational complexity and improved performance of the adaptive algorithm is introduced. It uses auxiliary subbands and a modified filter bank with decimated subbands. It avoids the aliasing distortions encountered in critically decimated overlapping filter banks as well as the spectral gaps in nonoverlapping filter banks. The authors show that this structure has a lower computational complexity than previously reported structures. computer simulations are included showing the improvement in performance that can be achieved with the new structure operating as an adaptive line enhancer (ALE) compared with the conventional ALE.< >

关键词： Adaptive filters Finite impulse response filter Filter bank Computational complexity Convergence Line enhancers Narrowband Adaptive algorithm Echo cancellers Teleconferencing

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Partial shape recognition: a landmark-based approach

Partial shape recognition: a landmark-based approach

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IEEE International Conference on Systems, Man and Cybernetics

作者： N. Ansari E.J. Delp Center for Communications and Signal Processing Electrical and Computer Engineering Department New Jersey Institute of Technology Newark NJ USA Computer Vision and Image Processing Laboratory School of Electrical Engineering Purdue University IN USA

A technique to guide landmark matching known as hopping dynamic programming is described. The location of the model in the scene is estimated with a least-squares fit. A heuristic measure is then computed to decide if the model is in the scene. The shape features of an object are the landmarks associated with the object. The landmarks of an object are defined as the points of interest of the object that have important shape attributes. Examples of landmarks are corners, holes, protrusions, and high-curvature points.< >

关键词： Shape measurement Layout computer vision Pattern recognition signal processing Image processing Laboratories Performance evaluation Least squares approximation Feature extraction

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Parameter extraction of microwave transistors using tree annealing

Parameter extraction of microwave transistors using tree ann...

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IEEE/Cornell Conference on Advanced Concepts in High Speed Semiconductor Devices and Circuits

作者： M.B. Steer G.L. Bilbro R.J. Trew S.G. Skaggs High Frequency Electronics Laboratory and the Center for Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

The authors have developed an alternative formulation of simulated annealing using a tree-based Metropolis procedure called tree annealing. Tree annealing is suited to continuous optimization problems and, in particular, to transistor parameter extraction. The tree annealing optimization algorithm was used to extract the parameters of the HBT (heterojunction bipolar transistor) of U.K. Mishra et al. (IEDM Tech. Dig., p.180-3, Dec. 1988) using a physically based equivalent circuit and deembedded scattering parameter measurements from 45 MHz to 26.5 GHz. Good results were obtained from the parameter extraction technique, and the ability of MFA not to be locked in local minima enabled a physically based equivalent circuit model to be used. Tree annealing is essentially a smart random search technique and so requires many more functional evaluations than do gradient-based minimization algorithms. However, no startling guess is required, and the bounds on parameter values can be widely separated with little effect on optimization time.< >

关键词： Parameter extraction Microwave transistors Simulated annealing Equivalent circuits Combinatorial mathematics Robustness Frequency Laboratories Microwave communication signal processing

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Simulated hearing loss as a baseline for the assessment of auditory function in cochlearly impaired listeners

Simulated hearing loss as a baseline for the assessment of a...

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Annual Northeast Bioengineering Conference

作者： S. Buus M. Florentine Center for Communication and Digital Signal Processing (416 DA) Department of Electrical and Computer Engineering Northeastern University Boston MA USA Communication Research Laboratory (226 FR) Department of Speech-Language Pathology and Audiology Northeastern University Boston MA USA

An overview is presented of results obtained in listeners with real and simulated impairments. Spectral processing is assessed by psychoacoustical tuning curves and growth-of-masking functions; temporal processing is assessed by temporal integration and gap detection thresholds. When comparisons are made to normal listeners tested in the quiet, impaired listeners generally show deficits on all these tasks. When the comparisons are made to simulated impairments, some impaired listeners show no deficits, whereas others still show deficits. These results indicate that abnormal intensity perception is responsible for some, but not all, of impaired listeners' apparent deficits in spectral and temporal processing. In many cases, however, it appears that spectral and temporal processing, per se, are altered in the impaired auditory system.< >

关键词： Deafness Psychoacoustic models Ear Frequency Auditory system Tuning Acoustic noise Noise shaping Testing Spectral shape

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

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

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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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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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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： TRANSFER FUNCTIONS catalogs Network Designers LBR gene Multiplying circuits

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