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AN ANALYSIS OF NONLINEAR BEHAVIOR IN DELTA-SIGMA MODULATORS

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS 1987年第6期34卷 593-603页

作者： ARDALAN, SH PAULOS, JJ Center for Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

This paper introduces a new method of analysis for deltasigma modulators based on modeling the nonlinear quantizer with a linearized gain, obtained by minimizing a mean-square-error criterion [7], followed by an additive noise source representing distortion components. In the paper, input signal amplitude dependencies of delta-sigma modulator stability and signal-to-noise ratio are analyzed. It is shown that due to the nonlinearity of the quantizer, the signal-to-noise ratio of the modulator may decrease as the input amplitude increases prior to saturation. Also, a stable third-order delta-sigma modulator may become unstable by increasing the input amplitude beyond a certain threshold. Both of these phenomena are explained by the nonlinear analysis of this paper. The analysis is carried out for both dc and sinusoidal excitations.

关键词： Delta modulation signal to noise ratio Amplitude modulation Nonlinear distortion Delta-sigma modulation Quantization Circuits signal processing Feedback Additive noise

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FIXED-POINT ROUNDOFF ERROR ANALYSIS OF THE EXPONENTIALLY WINDOWED RLS ALGORITHM FOR TIME-VARYING SYSTEMS

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IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND signal processing 1987年第6期35卷 770-783页

作者： ARDALAN, SH ALEXANDER, ST Center for Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

A fixed-point roundoff error analysis of the exponentially windowed RLS algorithm is presented. It is shown that a tradeoff exists in the choice of the forgetting factor λ. In order to reduce the sensitivity of the algorithm to additive noise, λ must be chosen close to one. On the other hand, the roundoff error increases as \lambda \rightarrow 1 . It is shown that the algorithm is stabilized with λ < 1. The algorithm may diverge for \lambda \rightarrow 1 . To derive the theoretical results, it is assumed that the input signal is a white Gaussian random process. Finally, simulations are presented which confirm the theoretical findings of the paper.

关键词： Roundoff errors Error analysis Algorithm design and analysis Resonance light scattering Time varying systems signal processing algorithms Kalman filters Additive noise Noise reduction signal processing

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ANALYSIS OF DISTRIBUTION LINE CARRIER PROPAGATION USING THE BUS IMPEDANCE MATRIX

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IEEE TRANSACTIONS ON POWER DELIVERY 1987年第4期2卷 976-984页

作者： AMOURA, FK ONEAL, JB Center for Communications and Signal Processing Electrical and Computer Engineering Department North Carolina State University Raleigh NC USA

Distribution line carrier (DLC) is a communication system used in automated distribution systems to transmit data between the substation and certain locations on the distribution primary and secondary. Extensive DLC propagation measurements have shown that the propagation of signals on a power distribution line is difficult to predict because of the complexity and variability of distribution systems. This paper presents an efficient and comprehensive analytical tool for predicting DLC signal propagation over complex distribution systems. This paper develops a three-phase bus impedance matrix, which consists of 3×3 transfer impedance submatrices. These submatrices represent the general transfer function which relates the three-phase received voltage vector at any point of interest to any three-phase transmitted (injected) current vector at any point of interest. The method described here is an extension of the three-phase bus impedance approach used for 60 Hz power distribution.

关键词： Impedance Voltage Transfer functions Transmitters Power measurement signal analysis Frequency signal processing Distributed computing Data engineering

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DISTRIBUTION LINE CARRIER SENSITIVITY ANALYSIS USING BUS IMPEDANCE MATRIX

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IEEE TRANSACTIONS ON POWER DELIVERY 1987年第4期2卷 985-991页

作者： AMOURA, FK ONEAL, JB Center for Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

In a previous paper[1] we described the use of a bus impedance matrix approach for determining the signal strength of distribution line carrier signals. The technique used bus impedance matrices to calculate transimpedances which are the ratios of the voltage at any point on the line to the current injected at any point on the line. In the current paper we apply sensitivity analysis to this bus impedance approach and show how simply new transimpedances can be obtained from the original values when changes in the distribution line are made.

关键词： Sensitivity analysis Impedance Uncertainty Voltage signal processing Distributed computing Power system modeling Transmitters signal analysis Power systems

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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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A LAYER-STRIPPING FAST ALGORITHM FOR RECONSTRUCTING AN ELASTIC MEDIUM FROM ITS COMPRESSIONAL WAVE REFLECTION RESPONSE

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IEEE JOURNAL OF OCEANIC engineering 1987年第2期12卷 423-432页

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

A fast algorithm for recovering profiles of density and compressional (P) and shear-vertical (SV) wave speeds as functions of depth for the inverse seismic problem in a continuous layered elastic medium is obtained. This algorithm differs from previous fast algorithms for this problem since it requires only the compressional wave P-P reflection response at the surface of the medium, for three different slownesses or angles of incidence. Previous algorithms have required shear stress data in the form of the P-SV and SV-SV reflection responses, making them unsuitable for an ocean environment. This algorithm is thus much more suitable for reconstructing the ocean floor from pressure data taken in the ocean. The algorithm is exact, and it includes the effects of multiple reflections and mode conversions. A computer run illustrates the performance of the algorithm on synthetic data.

关键词： Oceans Inverse problems signal processing algorithms Integral equations Acoustic reflection Acoustic propagation Surface waves Sea surface Probes Response surface methodology

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MULTIDIMENSIONAL INVERSE SCATTERING - AN ORTHOGONALIZATION FORMULATION

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JOURNAL OF MATHEMATICAL PHYSICS 1987年第7期28卷 1481-1491页

作者： YAGLE, AE Communications and Signal Processing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann Arbor Michigan 48109

The three‐dimensional Schrödinger equation inverse scattering problem is solved using an orthogonalization approach. The plane waves propagating in free space are orthogonalized with respect to an inner product defined in terms of a Jost operator. The resulting integral equation is identical to the generalized Gel’fand–Levitan equation of Newton, although the present derivation is simpler and more physical than that of Newton. Newton’s generalized Marchenko equation is derived from the defining integral equation for the Jost operator. These integral equations are shown to be solved by fast algorithms derived directly from the properties of their solutions. This paper thus presents a simple interpretation of Newton’s two integral equations, two fast algorithms for solving these integral equations, and relations between the various approaches. This is a generalization of previously obtained results, which are also reviewed here, for the one‐dimensional inverse scattering problem.

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PHASE RECONSTRUCTION IN THE TRISPECTRUM DOMAIN

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IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND signal processing 1987年第6期35卷 895-897页

作者： PAN, R NIKIAS, CL Communications and Digital Signal Processing Laboratory Department of Electrical and Computer Engineering Northeastern University Boston MA USA

The phase reconstruction problem in the trispectrum domain is addressed in this correspondence. In particular, three different reconstruction algorithms are discussed and their performance is evaluated. The first two ... 详细信息

关键词： Radar detection Reconstruction algorithms Clutter signal processing algorithms Equations Nonlinear filters Detectors Data processing signal processing Recursive estimation

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Detection of artifacts in CT images using the consistency of the projection data

Detection of artifacts in CT images using the consistency of...

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Medical Imaging 1987

作者： Orun-Ozturk, Hatice Trussell, H. Joel Civanlar, M. Reha Center for Communications and Signal Processing Electrical and Computer Engineering Department North Carolina State University RaleighNC27695-7911 United States

In computerized tomography, certain type of artifacts can be detected if the consistency of the reconstruction is checked using the available information. A reconstructed image is said to be consistent if it satisfies all a priori knowledge. This paper demonstrates how the consistency principle can be used to detect reconstruction artifacts. © 1987 SPIE. All rights reserved.

关键词： computerized tomography

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An analysis of sinusoidally excited delta-sigma modulators

An analysis of sinusoidally excited delta-sigma modulators

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

作者： S. Ardalan J. Paulos Center for Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

This paper introduces a new method of analysis for Delta-Sigma Modulators based on modeling the nonlinear quantizer with a linerized gain, obtained by minimizing a mean-square-error criterion[7], followed by an additive noise source representing distortion components. In the paper, input-signal amplitude dependencies of Delta-Sigma Modulator stability and signal to noise ratio are analyzed. It is shown that due to the nonlinearity of the quantizer, the signal-to-noise ratio of the modulator may decrease as the input amplitude increases prior to saturation. Also, a stable third-order Delta-Sigma Modulator may become unstable by increasing the input amplitude beyond a certain threshold. Both of these phenomenon are explained by the nonlinear analysis of this paper. The analysis is carried out sinusoidal excitations.

关键词： Delta modulation signal to noise ratio Additive noise Amplitude modulation signal analysis Noise level Distortion Delta-sigma modulation Quantization signal processing

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