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IEE Colloquium on Digitized Speech Communication via Mobile Radio

作者： C. Xydeas D. Baghbadrani A. Erwood Speech and Image Processing Laboratory Department of Electrical Engineering University of Manchester Institute of Science and Technology Manchester UK

The authors consider the role of noise cancellation and low bit rate speech coding in mobile radio systems. They discuss the reduction of acoustic noise in speech signals, and consider speech-channel coding. Diagrams ... 详细信息

关键词： Encoding Interference suppression Speech processing

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Cumulant based parameter estimation of multichannel moving-average processes

Cumulant based parameter estimation of multichannel moving-a...

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

作者： Y. Inouye G.B. Giannakis J.M. Mendel Department of Control Engineering Osaka University Toyonaka Osaka Japan Department of Electrical Engineering Thomton Hall University of Virginia Cologno VA USA Department of Electrical Engineering Systems Signal and Image Processing Institute University of Southern California Los Angeles CA USA

Given finite samples of a stationary, perhaps noisy, nonGaussian r-variate moving-average, MA(q) process, the authors study cumulant based identifiability conditions, under which the MA coefficient matrices, the input statistics, and the order q, can be uniquely determined. The selection of a unique representative from the equivalence class corresponding to a given cumulant structure involves less restrictions than that corresponding to a given covariance structure. They derive two algorithms for estimating the (possibly) nonminimum phase MA coefficient matrices.< >

关键词： Parameter estimation Covariance matrix Parametric statistics Gaussian processes Additive noise signal processing image processing Gaussian noise Phase estimation Econometrics

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String dictionary structure for Markov arithmetic encoding

String dictionary structure for Markov arithmetic encoding

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IEEE International Conference on Communications (ICC)

作者： Y. Bar-Ness S. Choi S. Politi The Center of Communication and Signal Processing Research Department of Electrical Engineering New Jersey Institute of Technology Newark NJ USA

Data from statistically unknown sources is generally difficult to compress with significant ratios. The compression scheme should have the ability to gather context information of the source in an adaptive manner. Arithmetic coding has that capability and can be made to outperform many other compression schemes known. The sliding dictionary, on the other hand, is a compression algorithm which is best suitable for hardware implementation on systolic-array parallel processors, but due to the statistical properties of its information context, it results in inferior compression ratios. A string dictionary structure is proposed that combines the advantages of both algorithms, offering the possibility of hardware implementation on VLSI, avoidance of encoding almost random information, and encoding with arithmetic codes.< >

关键词： Dictionaries Arithmetic Encoding Hardware Very large scale integration signal processing algorithms Data compression Adaptive signal processing Context Compression algorithms

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Polyphase FIR filters for the demodulation of chrominance signals

Polyphase FIR filters for the demodulation of chrominance si...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： C.H. Lu Center of Communications and Signal Processing Research Department of Electrical Engineering New Jersey Institute of Technology Newark NJ USA

The author presents a scheme and its polyphase FIR (finite-impulse-response) filter implementation for the demodulation of chrominance signal into in-phase and quadrature-phase components. The scheme applies to any system whose sampling frequency is related to the color subcarrier frequency by a rational factor. The authors presents the criteria for choosing a sampling frequency for the digitization of a TV studio signal and addresses the issue of digital demodulation of the chrominance component in a composite video signal.< >

关键词： Finite impulse response filter Demodulation signal processing Frequency Video compression TV Digital signal processing Video signal processing image storage Buffer storage

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Pulsewidth-constrained signaling and trellis coded modulation on the direct-detection optical channel

Pulsewidth-constrained signaling and trellis coded modulatio...

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IEEE Global Telecommunications Conference and Exhibition. Communications for the Information Age

作者： G.L. Bechtel J.W. Modestino Center of Communications and Digital Signal Processing Electrical and Computer Engineering Department Northeastern University Boston MA USA Electrical Computer and System Engineering Department Rensselaer Polytechnic Institute Troy NY USA

Pulsewidth-constrained signals are developed for use on the degraded direct-detection optical channel. A two-dimensional representation for these signals is obtained and used to design a trellis-coded-modulation (TCM) system for use on the optical channel. The theoretical advantage of optical TCM is shown, through use of the cutoff rate, to range from 7.5 to 9 dB, depending on the throughput rate of the system. The practical potential is shown, through the actual design of a TCM system, to be as high as 6.7 dB.< >

关键词： Pulse modulation Optical pulses Modulation coding Optical modulation Bandwidth Optical signal processing Optical noise Optical receivers AWGN Energy efficiency

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Performance of trellis encoded tamed frequency modulation

Performance of trellis encoded tamed frequency modulation

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IEEE Conference on Vehicular Technology (VTC)

作者： F. Morales-Moreno W. Holubowicz S. Pasupathy Center for Communication and Signal Processing Research Department of Electrical Engineering New Jersey Institute of Technology Newark NJ USA Department of Electrical Engineering Polytechnic University Brooklyn NY USA Department of Electrical Engineering University of Toronto Toronto ONT Canada

Combinations of convolutional codes and tamed frequency modulation (TFM) are optimized as one entity for rate 1/2 and decoder complexities of up to 256 states. It is concluded that the best codes found so far belong to a class of codes called matched codes, which have the property of minimizing the complexity of the optimal Viterbi decoder. Coding gains of up to 7.68 dB are reported. The reported codes are the best codes for use with TFM in a Gaussian noise channel and assuming Viterbi decoding. Some of these codes are found to be catastrophic, yet the coded TFM scheme is free of this problem. The codes obtained are found to be superior to those obtained with traditional optimization techniques.< >

关键词： Frequency modulation Decoding Convolutional codes Modulation coding Viterbi algorithm Gaussian noise Digital modulation Mobile communication Euclidean distance Satellite communication

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Broadband beamforming via acousto-optics

Broadband beamforming via acousto-optics

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Advances in Optical Information processing III 1988

作者： Lin, Shih-Chun Hong, John Boughton, R. Scott Psaltis, Demetri Aerospace Corporation Signal Processing Department P.O. Box 92957 Los AngelesCA90009 United States California Institute of Technology Department of Electrical Engineering PasadenaCA91125 United States Science Center Rockwell International Corp. P.O. Box 1085 Thousand OaksCA91360 United States

A novel broadband beamformer based on space-integrating, interferometric multichannel acousto-optic correlators was proposed. Both analysis and experiments were carried out to validate the concept. Simultaneous beamforming and pulse compression were demonstrated by an experimental simulation with a 126-bit PN coded signal of 50-MHz bandwidth. Analysis also showed that the system was suitable for multiple beamforming. The responses of the system to narrow (cw) and wideband (random noise) jammers, both on-boresight and off-boresight, were investigated experimentally. Results showed that, against these interferences, the system was quite robust due to the processing gain, even for the worst case where the jammers was on-boresight and its frequency coincided with the signal carrier. However, the system's sensitivity was reduced by a factor of four for the wideband jammer and a factor of ten for the narrow band jammer. The dynamic range of the system was measured to exceed 20 dB, only to be limited by detector saturation and Bragg cell non-linearity. The system could be made adaptive. © 1988 SPIE. All rights reserved.

关键词： Beamforming

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Adaptive antenna arrays using eigenvector methods

Adaptive antenna arrays using eigenvector methods

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Antennas and Propagation Society International Symposium

作者： A. Haimovich Y. Bar-Ness Dept. of Electr. Eng. New Jersey Inst. of Technol. Newark NJ USA Center for Communications and Signal Processing Research Electrical Engineering Department New Jersey Institute of Technology Newark NJ USA

The authors consider the application of eigenvector techniques to the solution of interference problems. The conventional minimum-variance signal-to-noise-ratio criteria are extended to a case in which the eigenstructure of the array correlation matrix is used to cancel directional interference sources. It is shown that while the method has good interference cancellation properties, it results in higher pattern distortion than conventional arrays.< >

关键词： Adaptive arrays Antenna arrays Interference cancellation signal to noise ratio Background noise Noise cancellation Sensor arrays Adaptive signal processing Array signal processing signal synthesis

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OPTIMAL SYSTOLIC DESIGN FOR THE TRANSITIVE CLOSURE AND THE SHORTEST-PATH PROBLEMS

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IEEE TRANSACTIONS ON COMPUTERS 1987年第5期36卷 603-614页

作者： KUNG, SY LO, SC LEWIS, PS Signal and Image Processing Institute Department of Electrical Engineering University of Southern California

Due to VLSI technological progress, algorithm- oriented array architectures, such as systolic arrays, appear to be very effective, feasible, and economic. This paper discusses how to design systolic arrays for the transitive closure and the shortest path problems. We shall focus on the Warshall algorithm for the transitive closure problem and the Floyd algorithm for the shortest path problem. These two algorithms share exactly the same structural formulation; therefore, they lead to the same systolic array design. In this paper, we first present a general method for mapping algorithms to systolic arrays. Using this methodology, two new systolic designs for the Warshall-Floyd algorithm will be derived. The first one is a spiral array, which is easy to derive and can be further simplified to a hexagonal array. The other is an orthogonal systolic array which is optimal in terms of pipelining rate, block pipelining rate, and the number of input/output connections.

关键词： Algorithm mappings VLSI algorithms VLSI architectures optimal algorithms shortest path problem systolic arrays transitive closure problems

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COMMON PITFALLS IN THE APPLICATION OF STATIONARY PROCESS THEORY TO TIME-SAMPLED AND MODULATED signalS

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IEEE TRANSACTIONS ON COMMUNICATIONS 1987年第5期35卷 529-534页

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

The common practice of applying the theory of stationary stochastic processes to a cyclostationary process by introducing random phase(s) into the probabilistic model in order to stationarize the process can lead to erroneous results, such as incorrect formulas for power spectral density. This is illustrated by showing that commonly used formulas for signals that have undergone frequency conversion or time sampling can be incorrect. The source of error is shown to be inappropriate phase-randomization procedures. The correct procedure is described, and corrected formulas are given. The problem is further illustrated by showing that commonly used resolution and reliability (mean and variance) formulas for spectrum analyzers must be corrected for cyclostationary signals. It is explained that all corrections to formulas reflect the effects of spectral correlation. These effects are inappropriately averaged out by inappropriate phase-randomization procedures. It is further explained that these inappropriate procedures destroy the important property of ergodicity of the probabilistic model.

关键词： signal processing Stochastic processes Phase modulation Frequency conversion signal sampling Spectral analysis Pulse modulation signal resolution Analytical models

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