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IEEE Conference on Vehicular Technology (VTC)

作者： T.L. Staley R.C. North W.H. Ku J.R. Zeidler Department of Electrical and Computer Engineering University of California San Diego La Jolla CA USA RDT&E Division Naval Command Control and Ocean Surveillance Center San Diego CA USA

This paper presents a framework for analyzing the error rate performance of multichannel coherent reception of MPSK systems operating over frequency selective, slowly fading channels. Each of the baseband channels is assumed to be a bandlimited two-sided discrete path model with correlated complex Gaussian taps, which is assumed to have resulted from an underlying Gaussian wide-sense-stationary uncorrelated-scattering (WSSUS) physical channel followed by a lowpass filter. By working with this "resolved channel", the resulting performance evaluation incorporates whatever resolution is inherent in the bandwidth of interest. An expression for the received phase density function is developed. The probability of symbol error, conditioned on the interfering symbols, is then determined, and the cases for which a closed form or efficient numerical evaluation is possible are specified. The symbol error rate is then obtained by summing over the interfering symbols. A progressive ISI bound is then discussed for cases when faster computation is required. Examples are then provided to demonstrate the versatility of the method.

关键词： Frequency Fading Error analysis Phase shift keying Bandwidth Pulse shaping methods Performance analysis Density functional theory Signal resolution Oceans

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Channel estimate-based performance prediction for coherent linear modulation on slowly fading channels

Channel estimate-based performance prediction for coherent l...

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MILCOM, Military Communications Conference

作者： T.L. Staley R.C. North R.A. Axford W.H. Ku J.R. Zeidler Department of Electrical and Computer Engineering University of California San Diego La Jolla CA USA RDT&E Division NRaD Naval Command Control and Ocean Surveillance Center San Diego CA USA

This paper describes a framework for predicting the error rate performance of linearly modulated coherent systems operating over frequency selective, slowly fading channels, when the statistics of the bandlimited two-sided discrete FIR model for the channel are available from a channel estimator. This work supports an upcoming experiment in which channel estimates obtained with one modulation scheme will be used to predict the performance of higher order modulation schemes. The focus of this paper is the mathematical framework for the theoretical performance prediction. Linear memoryless modulation is assumed, providing a a very general signal model that includes M-PSK and M-QAM. The channel model is slowly fading, with correlated complex Gaussian taps, incorporating both the flat and frequency selective cases. Expressions for the error probability are presented, and the cases for which closed form or acceptable numerical solutions exist are delineated. A new recursive method for solving the Rician-fading main path case is presented. The high-data-rate maritime line-of-sight channel is used to demonstrate the use fullness of the method.

关键词： Fading Chirp modulation Error analysis Rayleigh channels Frequency estimation Pulse shaping methods Higher order statistics Amplitude modulation Quadrature amplitude modulation Pulse modulation

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Phase correction for coherent noise reduction in short-range radar measurements

Phase correction for coherent noise reduction in short-range...

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： S.G. Beaven S.P. Gogineni P. Kanagaratnam Development Test & Evaluation Division Naval Command Control and Ocean Surveillance Center San Diego CA USA Radar Systems and Remote Sensing Laboratory Department of Electrical and Computer Engineering University of Kansas Lawrence KS USA

Short-range scatterometer systems are used to obtain radar backscatter signatures for understanding the interaction between electromagnetic energy and geophysical media in a number of remote sensing applications. Unlike long-range and intermediate-range radar systems, the sensitivity of short-range radars is not limited by thermal noise, but rather by reflections and leakage signals from the antenna and RF section. These leakage signals and their sidelobes are the primary sources of unwanted signals (coherent noise) in short-range FM radar systems. The authors have employed coherent noise reduction techniques to reduce the effects of these unwanted signal sources. Reduction of these coherent noise sources is critical to obtaining accurate backscatter measurements from geophysical targets. Recent advances include the use of phase correction to overcome limitations due to drift of local oscillators and effects of temperature changes on the system. The authors present results from the standard and phase-corrected coherent noise reduction techniques. These techniques increased the dynamic range of field and laboratory measurements of radar backscatter from sea ice and allows the authors to use data from past experiments that had previously been discarded due to low signal-to-noise ratio.

关键词： Noise reduction Radar antennas Radar remote sensing Backscatter Radar measurements Geophysical measurements Sea measurements Radar applications Radar scattering Electromagnetic scattering

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Phase stabilization of reference signals in analog fiber-optic links

Phase stabilization of reference signals in analog fiber-opt...

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International Topical Meeting on Microwave Photonics (MWP)

作者： M. Shadaram V. Gonzalez J. Ceniceros N. Shah J. Mayers S. Pappert D. Lafaw Electrical and Computer Engineering Department University of Texas El Paso El Paso TX USA Control and Ocean Survedhce Center Research Development Test & Evaluation Division Naval Command San Diego CA USA Laboratory of Physical Science College Park MD USA

A feedback technique that utilizes a special optical modulator is used to reduce the phase noise of RF signals in microwave fiber-optic links. Experimental results indicate a reduction in the phase noise of a 150 MHz ... 详细信息

关键词： Phase noise Frequency Optical receivers Optical feedback Optical modulation Optical noise Phase modulation Optical transmitters Phase detection Optical sensors

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Book reviews

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Minds and Machines 1996年第2期6卷 239-285页

作者： Abbott, Barbara Herskovits, Annette Peterson, Philip L. Mele, Alfred R. Cole, David J. Crevier, Daniel Pelletier, Francis Jeffry Berkeley, Istvan S. N. Kitts, Brendan J. Brown, Mike Paliouras, George Department of Linguistics and Languages Michigan State University East Lansing USA Department of Philosophy Michigan State University East Lansing USA Program in Applied Linguistics Boston University Boston USA Department of Philosophy Syracuse University Syracuse USA Department of Philosophy Davidson College Davidson USA Department of Philosophy University of Minnesota Duluth USA Department of Electrical Engineering École de Technologie Supérieure Université du Québec Montréal Canada Department of Philosophy University of Alberta Edmonton Canada Department of Computing Science University of Alberta Edmonton Canada Biological Computation Project University of Alberta Edmonton Canada Center for Complex Systems Brandeis University Waltham USA Department of Computer Science University of Manchester Manchester U.K.

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GLOBAL INTERNAL STABILIZABILITY DOES NOT IMPLY GLOBAL EXTERNAL STABILIZABILITY FOR SMALL SENSOR DISTURBANCES

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IEEE TRANSACTIONS ON AUTOMATIC control 1995年第12期40卷 2119-2122页

作者： FREEMAN, R Center for Control Engineering and Computation Department of Electrical and Computer Engineering University of California Santa Barbara CA USA

It was shown in [1] that for control-affine nonlinear systems, global asymptotic stabilizability via continuous state feedback implies global input-to-state stabilizability with respect to actuator disturbances. We show that the analogous result for sensor disturbances does not hold: we construct a second-order system which admits a continuous memoryless globally asymptotically stabilizing state feedback controller but for which no such controller can prevent finite escape times from every initial condition in the presence of small sensor disturbances.

关键词： Asymptotic stability Actuators Sensor systems control systems Nonlinear systems Nonlinear control systems State feedback Robust stability control theory Working environment noise

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Backstepping Design with Nonsmooth Nonlinearities *

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IFAC Proceedings Volumes 1995年第14期28卷 435-440页

作者： R.A. Freeman P.V. Kokotović Center for Control Engineering and Computation Dept. of Electrical and Computer Engineering University of California Santa Barbara CA 93106 Telephone: (805) 893-4691

We develop tools for backstepping with Lyapunov functions and control laws which are locally Lipschitz but not differentiable. We use Clarke’s generalized gradient and its associated calculus to show that the locally Lipschitz backstepping construction is essentially the same as the differentiable one. Our recursive method is constructive and yields an explicit expression for the control law.

关键词： Backstepping nonsmooth Lyapunov functions generalized gradient

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Tracking controllers for Systems Linear in the Unmeasured States *

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IFAC Proceedings Volumes 1995年第14期28卷 577-582页

For nonlinear systems in extended strict feedback form, where unmeasured states enter linearly, we construct dynamic partial state feedback controllers that achieve the global asymptotic tracking of given reference tr... 详细信息

关键词： Nonlinear systems global tracking dynamic partial state feedback

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A dual-mode algorithm for blind equalization of qam signals: cadama 29

A dual-mode algorithm for blind equalization of qam signals:...

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29th Asilomar Conference on Signals, Systems and computers, ACSSC 1995

作者： Axford, R.A. Milstein, L.B. Zeidler, J.R. Communications Department Control and Ocean Surveillance Center RDTE Division Naval Command San DiegoCA921 52-5001 United States Department of Electrical and Computer Engineering University of Califomia at San DiegoCA92093 United States

ISBN: (纸本)0818673702

The misadjustment exhibited by the constant modulus algorithm (CMA) can be excessive when it is used for blind equalization of QAM signals, thus degrading the performance of decision-directed carrier recovery algorithms. This paper introduces a hybrid blind equalization algorithm, the CMA-assisted decision adjusted modulus algorithm (CADAMA), that exhibits reductions in misadjustment on the order of 18 to 25 dB for higher order QAM constellations. CADAMA employs CMA to perform initial adjustment of the equalizer, and switches to decision adjusted modulus algorithm (DAMA) mode when the amplitude equalization has been sufficiently accomplished. DAMA is based on a phase-blind cost function that goes to zero at each ring of the QAM constellation. © 1995 IEEE.

关键词： Blind equalization

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First passage risk-sensitive criterion for stochastic evolutions

First passage risk-sensitive criterion for stochastic evolut...

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American control Conference (ACC)

作者： C.D. Charalambous J.L. Hibey Measurement and Control Engineering Research Center College of Engineering Idaho State University Pocatello ID USA Department of Electrical and Computer Engineering Old Dominion University Norfolk VA USA

The purpose of this paper is to investigate in an infinite dimensional space, the first passage problem with a risk-sensitive performance criterion, and to illustrate the asymptotic behavior of the associated value function, as related to differential games arising in robust control theory. The model of interest is described by a controlled stochastic evolution with small Wiener noise intensity. The Wiener and state processes take values in infinite dimensional Hilbert spaces. The objective is to control the evolution of the state process, so as to keep it in some compact set G. By using a logarithmic transformation, it is shown that in the limit as the small noise parameter, /spl epsiv//spl rarr/0, the risk-sensitive value function converges to the value of a deterministic differential game. In the limit as the risk parameter, /spl theta//spl rarr/0, the risk-sensitive value function converges to the value function corresponding to the mean escape time problem. In addition, a lower bound on the first escape time is derived which is slightly different from the known bound for finite dimensional systems. The magnitude of the lower bound derived here, increases as /spl theta/ increases, thus robustness is achieved.

关键词： Stochastic processes Hilbert space Equations Electric variables measurement control engineering Educational institutions Game theory Robust control Stochastic resonance Robustness

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