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DEGREES OF CYCLOSTATIONARITY AND THEIR APPLICATION TO signal-DETECTION AND ESTIMATION

signal processing 1991年第3期22卷 287-297页

作者： ZIVANOVIC, GD GARDNER, WA Computer Systems Design Laboratory “Boris Kidrič” Institute Vinča P.O. Box 522 11001 Belgrade Yugoslavia Signal Processing Group Department of Electrical Engineering & Computer Science University of California Davis CA 95616 USA

The problem of defining an appropriate measure of the degree of nonstationarity for stochastic processes that exhibit cyclostationarity is addressed. After discussing several candidate measures of degree of nonstationarity, one particularly promising measure is adopted. By decomposing this measure, several component measures are arrived at. Bounds on these measures are derived and their utility in applications involving signal detection and estimation is established. Examples are presented to illustrate the calculation of degrees of nonstationarity for several types of cyclostationary signals.

关键词： CYCLOSTATIONARY PROCESS DEGREE OF CYCLOSTATIONARITY INSTANTANEOUS SPECTRUM SPECTRAL CORRELATION

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Low-complexity multi-mode VXC using multi-stage optimization and mode selection (speech coding)

Low-complexity multi-mode VXC using multi-stage optimization...

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

作者： M. Johnson T. Taniguchi Department of Electrical Engineering and Computer Science MIT Cambridge MA USA Speech Signal Processing Fujitsu Laboratories Limited Kawasaki Japan

The authors propose an algorithm in which multi-mode coding is a transparent adaptation of multi-stage VXC (vector excitation coding) requiring almost zero additional computation. In the process, it is shown how the cost of the jointly optimized multi-stage VXC can be minimized using a backward-transform implementation of the perceptually orthogonal VXC (POVXC) algorithm previously proposed by the authors. It is shown that the performance of such a coder, while not as good as that of a normal multi-mode coder, is noticeably better than that of a normal POVXC.< >

关键词： speech coding Linear predictive coding speech processing Adaptive filters Bit rate Cost function Vocoders Computational complexity Vector quantization Code standards

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A NOVEL NONLINEAR FILTER FOR IMAGE-ENHANCEMENT 2

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CONF ON IMAGE processing ALGORITHMS AND TECHNIQUES

作者： YU, TH MITRA, SK KAISER, JF Signal and Image Processing Laboratory Department of Electrical and Computer Engineering University of California Santa Barbara 93106 CA United States Bell Communications Research Inc. Room 2A-281 445 South Street Morristown 07962-1910 NJ United States

ISBN: (纸本)0819405515

Recently, a very simple nonlinear algorithm, the so-called Teager's algorithm, has been introduced to calculate the energy of a one-dimensional sequence [1]. In this paper, this algorithm is extended to two-dimensional signals and applied to the contrast enhancement of images. Initial simulation results indicate that the proposed approach yields a superior and visually pleasing enhancement of natural images. The new algorithm is very simple and permits fast implementation. © 1991 SPIE. All rights reserved.

关键词： Image enhancement

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Pitch sharpening for perceptually improved CELP, and the sparse-delta codebook for reduced computation

Pitch sharpening for perceptually improved CELP, and the spa...

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

作者： T. Taniguchi M. Johnson Y. Ohta Department of Electrical Engineering and Computer Science MIT Cambridge MA USA Speech Signal Processing Fujitsu Laboratories Limited Kawasaki Japan

The authors introduce two techniques for improving low-bit-rate CELP (code excited linear prediction) speech coders. The sparse-delta stochastic codebook is a recursive codebook design which can be searched using roughly 5% of the computational load required to search a full Gaussian codebook. Pitch sharpening is a class of algorithms which attempt to improve the perceptual quality of CELP by limiting the feedback of low-amplitude noiselike information to the adaptive codebook. Simulation results are presented for sparse-delta, ternary sparse-delta, and simplified-search sparse-delta coders, and for reduced-gain and sparse-adaptive-codebook pitch sharpening algorithms.< >

关键词： Stochastic resonance Books Feedback Stochastic processes Bit rate Finite impulse response filter Equations speech synthesis Code standards Linear predictive coding

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A new class of nonlinear filters for image enhancement

A new class of nonlinear filters for image enhancement

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

作者： S.K. Mitra H. Li I.-S. Lin T.-H. Yu Signal and Image Processing Laboratory Department of Electrical and Computer Engineering University of California Santa Barbara CA USA

Two types of very simple two-dimensional nonlinear filters are introduced and applied to image contrast enhancement. The first type is based on a generalization of the Teager's algorithm. A theoretical analysis has shown that this type of nonlinear filter works like a local-mean-weighted highpass filter. Based on this analysis, a second type of nonlinear filter has been developed which works like local-mean-weighted bandpass filter. The proposed image contrast enhancement technique is based on combining the original image with its filtered version obtained using one of the two nonlinear filters. Very high quality enhancement has been achieved for natural images.< >

关键词： Nonlinear filters Image enhancement Band pass filters Filtering signal processing Image processing Laboratories Histograms Brightness Pixel

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speech RECOGNITION BY A SELF-ORGANIZING FEATURE FINDER

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International Journal of Neural Systems 1991年第1N02期2卷 55-78页

作者： S.Z. Lerner J.R. Deller, Jr. GTE Laboratories Inc. 40 Sylvan Rd. Waltham MA 02254 USA (617) 466–2959 Michigan State University Department of Electrical Engineering/258 EB Control Systems and Signal Processing Group: Speech Processing Laboratory East Lansing MI 48824–1226 USA (517) 353–8840

A self-organizing neural network is presented which automatically learns the number and type of spectral features from speech examples. The learning algorithm is analyzed with respect to its convergence and stability properties. The “strength” of the presence of the learned features is registered by the network to effect recognition of further speech presentations. The network consists of two layers of feature detectors, each layer of which is self-organized, and the outputs of the second layer are time-aligned in the present design using dynamic time warping. The significance of the two-layer structure, as well as general architectural advantages of the network, are discussed. Results of experiments involving various isolated word recognition tasks, including single and multi-speaker training and recognition, and the recognition of speech of a nonverbal individual, are reported.

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Efficient design and implementation of FIR filter banks with equal passband widths

Efficient design and implementation of FIR filter banks with...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： T. Saramaki J. Vidiscakova S.K. Mitra Signal Processing Laboratory Tampere University of Technology Tampere Finland Department of Electronics Slovak Technical University Bratislava Slovakia Department of Electrical and Computer Engineering University of California Santa Barbara CA USA

An approach is presented for efficiently designing and implementing FIR (finite impulse response) filter banks with equal passband bandwidths. The overall bank of L filters is generated from a prototype 2Lth-band filter with the aid of a few additional coefficients and adders. The attractive properties of these filter banks are that the sum of filter outputs is guaranteed to be a pure delay and the passband bandwidths are the same for all the filters.< >

关键词： Finite impulse response filter Passband Filter bank Band pass filters Prototypes Stacking Channel bank filters Transfer functions Bandwidth Delay

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Reformulation of Chang's criterion for the absence of limit cycles using bilinear transform

Reformulation of Chang's criterion for the absence of limit ...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： T.C. Macedo T. Laakso P.S.R. Diniz I. Hartimo Department of Electrical Engineering Federal University of Rio de Janeiro (COPPE-EE) Rio de Janeiro Brazil Laboratory of Signal Processing and Computer Technology Helsinki University of Technology Espoo Finland

A procedure for the reformulation of Chang's criterion (1981) for the absence of zero-input limit cycles in recursive digital filters is presented. The technique employs the standard bilinear transform to convert a frequency-domain criterion into a polynomial form in terms of matrix transformations. The use of the method is illustrated with design examples applied to determine the stability region for certain single-quantizer recursive filter structures. The results can be utilized, e.g., in the design of an error feedback network for a given filter such that limit cycles are eliminated.< >

关键词： Limit-cycles Feedback Digital filters Stability criteria Paper technology Difference equations Frequency conversion Matrix converters Finite wordlength effects Adaptive filters

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Real-time high-ratio image compression using adaptive VLSI neuroprocessors

Real-time high-ratio image compression using adaptive VLSI n...

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

作者： B.J. Sheu W.-C. Fang Department of Electrical Engineering Signal and Image Processing Institute University of Southern California Los Angeles CA USA Jet Propulsion Laboratory Advanced Computer Systems and Technology Section California Institute of Technology Pasadena CA USA

An adaptive VLSI neuroprocessor based on vector quantization algorithm has been developed for real-time high-ratio image compression applications. This VLSI neural-network-based vector quantization (NNVQ) module combines a fully parallel vector quantizer with a pipelined codebook generator for a broad area of data compression applications. The NNVQ module is capable of producing good-quality reconstructed data at high compression ratios more than 20. The vector quantizer chip has been designed, fabricated, and tested. It contains 64 inner-product neural units and a high-speed extendable winner-take-all block. This mixed-signal chip occupies a compact silicon area of 4.6*6.8 mm/sup 2/ in a 2.0- mu m scalable CMOS technology. The throughput rate of the 2- mu m NNVQ module is 2 million vectors per second and its equivalent computation power is 3.33 billion connections per second.< >

关键词： Image coding Very large scale integration Vector quantization Neural networks Data compression High performance computing Clustering algorithms Application software Image reconstruction CMOS technology

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A real-time VLSI neuroprocessor for adaptive image compression based upon frequency-sensitive competitive learning

A real-time VLSI neuroprocessor for adaptive image compressi...

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International Joint Conference on Neural Networks (IJCNN)

作者： W.-C. Fang B.J. Sheu O.T.-C. Chen Jet Propulsion Laboratory Advanced Computer Systems and Technology Section California Institute of Technology Pasadena CA USA Department of Electrical Engineering Signal and Image Processing Institute University of Southern California Los Angeles CA USA

The frequency-sensitive competitive learning (FSCL) algorithm and its associated VLSI neuroprocessor have been developed for adaptive vector quantisation (AVQ). Simulation results show that the FSCL algorithm is capable of producing a good-quality codebook for AVQ at high compression ratios of more than 20 in real time. This VLSI neural-network-based vector quantization design includes a fully parallel vector quantizer and a pipelined codebook generator to provide an effective data compression scheme. It provides a computing capability as high as 3.33 billion connections per second. Its performance can achieve a speedup of 750 compared with SUN-3/60 and a compression ratio of 33 at a signal-to-noise ratio of 23.81 dB.< >

关键词： Very large scale integration Image coding Frequency Neural networks Power capacitors Vector quantization CMOS technology Image reconstruction speech coding Data compression

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