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MILCOM, Military Communications Conference

作者： J.S. Goldstein I.S. Reed R.N. Smith Space Communications Branch Rome Laboratory US Air Force Rome NY USA Statistical Signal and Image Processing Laboratory Department of Electrical Engineering EEB 528 University of Southern California Los Angeles CA USA

This paper introduces low-complexity frequency domain approximations of optimal partially adaptive sensor array processors for space communications. Space-segment sensor arrays, for military and other critical communications links, require adaptivity to provide ECCM and mitigate interference. The size, weight, and power restrictions of such platforms, however, prohibit full adaptivity. The design of low-complexity reduced-rank processors are investigated in this paper. It is demonstrated that the performance of full-rank adaptive arrays is obtainable by low-rank processors through the use of frequency domain implementations of a cross-spectral metric.

关键词： Sensor arrays signal processing Array signal processing Adaptive arrays Discrete Fourier transforms Interference Frequency domain analysis Covariance matrix Discrete cosine transforms Narrowband

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Mean field approximation to multimodal motion estimation problem

Mean field approximation to multimodal motion estimation pro...

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European signal processing Conference (EUSIPCO)

作者： Thanh Dang Nguyen Kalman Fazekas Department of Electrical Engineering 200 Broun Hall Auburn University AL 36849 USA Department of Microwave Telecommunications Signal Processing Laboratory Technical University of Budapest Goldman ter 3 Budapest H-1111 Hungary

The 2D Markov Random Field (MRF) model, combined with the Bayesian estimation framework, has proved to be an efficient and reliable computing tool to the optical flow estimation problem. Specifically, we are investigating the multimodal approach, where complementary constraints are imposed on the optical flow model. However, this approach suffers from expensive computational requirements, which is the direct consequence of the large dimensions of the optimization problem. Recently, a deterministic optimization technique, namely the mean field approximation has been proposed, which not only provides satisfactory estimation result, but also reduces the computational cost drastically. Here we apply this new technique to the above mentioned multimodal motion estimation problem.

关键词： Image edge detection Approximation methods Bayes methods Estimation Optical imaging Motion estimation Computational modeling

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Image denoising for reduced-search fractal block coding

Image denoising for reduced-search fractal block coding

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Canadian Conference on electrical and computer engineering (CCECE)

作者： S. Bal W. Kinsner Data Networking and Software Telecommunications Research Laboratories Winnipeg MAN Canada Signal and Data Compression Laboratory Department of Electrical and Computer Engineering University of Manitoba Winnipeg MAN Canada

This paper examines the process of image denoising to improve the efficiency of the reduced-search fractal block coding (FBC) of greyscale images by reducing the first-order entropy of the image. The reduced-search FBC is a lossy compression technique that exploits the block-wise self-affinity of an image where portions of the image are represented by scaled and isometrically transformed copies of other portions of the image. The efficiency of this process increases with increased redundancy which is the result of lowering the entropy. Image denoising is concerned with separating noise from an image and then suppressing the noise as much as possible without altering the image itself. In this paper spatial smoothing and wavelet denoising are compared. It is shown that denoising increases the efficiency of reduced-search FBC. Spatial smoothing, however, causes a loss of signal that wavelet denoising does not. In either case, the reconstruction qualities of the peak-signal-to-noise ratio at approximately 34 dB and compression ratios of 18.9:1 and higher have been achieved. This is an improvement over the 31 dB and 18.1:1 for non-denoised images.

关键词： Image denoising Fractals Block codes Image coding Entropy Noise reduction Smoothing methods Pixel Additive noise Quantization

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Recognition of voiced speech from the bispectrum

Recognition of voiced speech from the bispectrum

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European signal processing Conference (EUSIPCO)

作者： Anastasios Delopoulos Maria Rangoussi Janne Andersen Division of Computer Science Department of Electrical Engineering National Technical University of Athens GR-15780 Athens Greece Digital Signal Processing Group Institute for Electronic Systems Aalborg University DK-9220 Aalborg Denmark

Recognition of voiced speech phonemes is addressed in this paper using features extracted from the bispectrum of the speech signal. Voiced speech is modeled as a superposition of coupled harmonics, located at frequencies that are multiples of the pitch and modulated by the vocal tract. For this type of signal, nonzero bispectral values are shown to be guaranteed by the estimation procedure employed. The vocal tract frequency response is reconstructed from the bispectrum on a set of frequency points that are multiples of the pitch. An AR model is next fitted on this transfer function. The AR coefficients are used as the feature vector for the subsequent classification step. Any finite dimension vector classifier can be employed at this point. Experiments using the LVQ neural classifier give satisfactory classification scores on real speech data, extracted from the DARPA/TIMIT speech corpus.

关键词： Speech Speech recognition Transfer functions Harmonic analysis Speech processing Feature extraction Estimation

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SOI material technology using plasma immersion ion implantation

SOI material technology using plasma immersion ion implantat...

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IEEE SOI-3D-Subthreshold Microelectronics Technology Unified Conference (S3S)

作者： X. Lu S.S.K. Iyer J. Min Z. Fan J.B. Liu P.K. Chu C. Hu N.W. Chueng Plasma Assisted Materials Processing Laboratory Department of Electrical Engineering and Computer Sciences University of California Berkeley CA USA Department of Physics and Materials Science City University of Hong Kong Hong Kong China

Silicon on insulator (SOI) devices have many attractive applications in integrated circuit technology. The high cost of manufacturing the SOI wafers, however, prevents it from being widely accepted for mass production. Separation by plasma implantation of oxygen (SPIMOX), an extremely high through-put SIMOX formation process using plasma immersion ion implantation (PIII) has demonstrated promising results. In this paper, an improvement on the SPIMOX process is presented. High-dose implantation is a costly procedure for the "smart cut" process. A low cost, high through-put implantation by hydrogen or helium plasma is demonstrated as a feasible, novel process for SOI technology using PIII.

关键词： Materials science and technology Plasma immersion ion implantation Silicon on insulator technology Costs Integrated circuit technology Manufacturing Mass production Plasma applications Plasma devices Plasma materials processing

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Neural Circuit For Matchhnismatch, Familiarity/novelty And Synchronization Detection In Saart Neural Networks

Neural Circuit For Matchhnismatch, Familiarity/novelty And S...

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International Symposium on signal processing and Its Applications (ISSPA)

作者： P. Lozo Weapons Systems Division Aeronautical and Maritime Research Laboratory Defence Science and Technology Organisation Salisbury SA Australia Department of Electrical and Electronic Engineering University of Adelaide Adelaide SA Australia Cooperative Research Centre for Sensor Signal and Information Processing SA Australia

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Neural Circuit For Self-regulated Attentional Learning In Selective Attention Adaptive Resonance Theory (saart) Neural Networks

Neural Circuit For Self-regulated Attentional Learning In Se...

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International Symposium on signal processing and Its Applications (ISSPA)

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A radio transmitter fingerprinting system ODO-1

A radio transmitter fingerprinting system ODO-1

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Canadian Conference on electrical and computer engineering (CCECE)

作者： J. Toonstra W. Kinsner Dept. of Electr. & Comput. Eng. Manitoba Univ. Winnipeg Man. Canada Department of Electrical and Computer Engineering Signal and Data Compression Laboratory University of Manitoba Winnipeg MAN Canada

This paper presents a new method for the capture, analysis, and classification of radio transmitter transients. This method involves the use of a capturing subsystem consisting of an Icom IC-R7000 communications receiver and a Sound Blaster 16 sound card running on a PC. The radio transients are sampled at 44,100 samples per second and have 16 bits accuracy. Once the transmitter transient has been captured, a genetic algorithm selects the critical features from the wavelet coefficients for classification. The selected wavelet coefficients are considered to be fingerprints, and are presented to a back propagation neural network for transmitter classification. The capturing and analysis system, ODO-1, is able to classify both transients of the same model type as well as individual transmitters with 100% accuracy on a small data base of transmitter fingerprints.

关键词： Radio transmitters Fingerprint recognition Transient analysis Genetic algorithms Wavelet analysis Loudspeakers Wavelet coefficients Neural networks Frequency synthesizers Algorithm design and analysis

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Adaptive soft limiter bootstrap separator for one-shot asynchronous CDMA channel with singular partial cross-correlation matrix

Adaptive soft limiter bootstrap separator for one-shot async...

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IEEE International Conference on Communications (ICC)

作者： N. Sezgin Y. Bar-Ness Center for Communications and Signal Processing Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ USA New Jersey Institute of Technology Newark NJ US Dept. of Electr. & Comput. Eng. New Jersey Inst. of Technol. Newark NJ USA

The adaptive bootstrap separator has been shown to perform better than the conventional decorrelation detector when used for synchronous code division multiple access (CDMA) channels, or with a one-shot matched filter bank for asynchronous channels when the cross-correlation of the partial sequences is nonsingular. In the later case, however, when the "partial cross-correlation" is singular, the separator weights fail to converge. We propose the use of a soft-limiting decision instead of a hard limiter for controlling the adaptive weights of the separator. We show that the algorithm weights converge, provided that the limiting threshold is not zero or not very large. Due to analytical difficulties, the actual steady state weights are not found, but are shown to exist. Simulation results support these claims. The bit error rate (BER) performance of the adaptive soft limiter bootstrap separator are also found by simulation and compared to the performance of the conventional decorrelator that uses the pseudoinverse of the cross-correlation matrix.

关键词： Particle separators Decorrelation Multiaccess communication Bit error rate Detectors Matched filters Weight control Programmable control Adaptive control Steady-state

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Detection of the complex amplitude distribution of a kinoform using an iterative Fourier-transform algorithm

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ELECTRONICS AND COMMUNICATIONS IN JAPAN PART II-ELECTRONICS 1996年第1期79卷 11-21页

作者： Akahori, H Faculty of Engineering Kanagawa Institute of Technology Atsugi Japan 243-02 Graduated in 1963 from the Department of Electrical Engineering Tokyo Institute of Technology and joined the Electrotechnical Laboratory of the Ministry of International Trade and Industry. Later he obtained a Dr. of Eng. degree. In 1987 he became a Professor in the Department of Information and Computer Sciences Kanagawa Institute of Technology. He has been engaged in research on optical information processing and digital holography.

This paper presents a method for recovering, by using the iterative Fourier-transform algorithm, the complex amplitude transmittance of a recorded one-dimensional Fourier transform-type kinoform. A method for estimating the phase-recording characteristic of the kinoform fabrication system by comparing the retrieved phase with the theoretical phase is also presented. The spatial variations of both the magnitude and phase inside each of the kinoform cells were evaluated to improve estimation of the phase-recording characteristic. The initial estimate of the kinoform phase given to the algorithm was derived using the knowledge that the recorded phase is an approximation of the phase to be recorded. The relationship between the shift of the central sampling point of the Fourier image from the optical axis and the retrieved phase of the kinoform is investigated;a kinoform phase pattern with a structure suitable for indirectly detecting the shift is then proposed. In an experiment using a kinoform fabrication system including a photographic process, the recorded phase distribution is retrieved at five sampling points of each cell. The phase-recording characteristic is estimated using the retrieved phase values. Next, a computer simulation is executed to reveal the influence of errors in the measurement of magnitude. The simulation result shows that the recorded phase distribution can approximately be retrieved when the rms error added to the magnitude is approximately 10 percent of its average. Furthermore, the validity of the phase distribution retrieved in the experiment is discussed.

关键词： Kinoform Gerchberg-Saxton algorithm phase retrieval phase-recording characteristic

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