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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： T.I. Laakso M. Lang T. Saramaki Nokia Research Center Helsinki Finland Electrical and Computer Engineering Department Rice University TX USA Signal Processing Laboratory Tampere University of Technology Tampere Finland

An approach for the design of limit-cycle-free digital fixed-point filters is proposed. By constraining the transfer function already in the design phase, it is guaranteed that the filter will be free from limit cycles and overflow oscillations in the direct form implementation. The design strategy also guarantees low roundoff noise. The proposed approach is illustrated with design examples. The examples show that typically a 50-100% increase in the filter order (as compared to standard elliptic design) is needed for the limit-cycle-free implementation of a lowpass filter with the direct form (DF) structure. Since the DF structure is very efficient to implement in signal processors, the proposed filters are very attractive for such environment, whereas dedicated filter structures (wave digital, state-space, etc.) easily result in a 3 to 4-fold implementation complexity.< >

关键词： Transfer functions Limit-cycles Electronic mail Digital filters Stability criteria Algorithm design and analysis Design engineering Laboratories Elliptic design signal processing

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Bayesian techniques for equalization of rapidly fading frequency selective channels

Bayesian techniques for equalization of rapidly fading frequ...

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IEEE Conference on Vehicular Technology (VTC)

作者： Gen-Kwo Lee M.P. Fitz S.B. Gelfand Vides Signal Processing Department Computer & Communication Research Laboratory Industrial Technology and Research Institute Hsinchu Taiwan School of Electrical Engineering Purdue University West Lafayette IN USA

This paper applies the Bayesian conditional decision feedback estimator (BCDFE) to rapidly fading frequency selective channels. The BCDFE is a model-based deconvolution algorithm which jointly estimates the transmitted data and channel parameters. The BCDFE applies joint symbol-by-symbol MAP demodulation and channel estimation to equalize channels, and consequently provides robust performance in rapidly fading channels. We provide a brief derivation of the BCDFE and characterize the performance on the land mobile radio channel. We assess the BCDFE's principle design characteristics and the resulting performance in both transient and steady-state operation. The effects of delay spread, Doppler spread, and co-channel interference on the BEP performance are also presented. The BCDFE demonstrates many of the desirable characteristics of an equalizer for mobile radio.< >

关键词： Bayesian methods Fading Frequency estimation Land mobile radio Feedback Deconvolution Demodulation Channel estimation Robustness Steady-state

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On the methodology for comparing learning algorithms: a case

On the methodology for comparing learning algorithms: a case

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Australian and New Zealand Conference on Intelligent Information Systems

作者： A. Bradley B. Lovell M. Ray G. Hawson Department of Electrical and Computer Engineering University of Queensland Brisbane Australia Cooperative Research Centre for Sensor Signal and Information Processing Australia Haemostatis Research Laboratory The Prince Charles Hospital Queensland Health Brisbane Australia

We explore several issues relevant to the benchmarking and comparison of machine learning algorithms. We illustrate those issues with a case study using the decision tree induction algorithms C4.5 (J. Quinlan, 1993) and multiscale classification (MSC) (A.P. Bradley and B.C. Lovell, 1994), multilayer perceptrons (MLP) and multivariable regression (MVR). Then for a "real world" problem we compare estimates of the true error rates for each classifier, first on a single train and test partition, and then using cross validated subsampling techniques. The relevance of the /spl chi//sup 2/ test is then discussed in relation to comparing the classifier accuracies. The paper concludes by evaluating the performance of these four fundamentally different approaches to the solution of this regression problem.< >

关键词： computer aided software engineering Decision trees Classification tree analysis Hospitals Machine learning algorithms Multilayer perceptrons Error analysis Blood Australia signal processing

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ADAPTIVE SET-MEMBERSHIP IDENTIFICATION IN O (M) TIME FOR LINEAR-IN-PARAMETERS MODELS

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IEEE TRANSACTIONS ON signal processing 1993年第5期41卷 1906-1924页

作者： DELLER, JR ODEH, SF Department of Electrical Engineering Control Systems and Signal Processing Group: Speech Processing Laboratory Michigan State University East Lansing MI USA Department of Electrical Engineering Control Systems and Signal Processing Group: Speech Processing Laboratory Michigan State University East Lansing MI USA Department of Electrical Engineering University of Jordan Amman Jordan

This paper describes some fundamental contributions to the theory and applicability of optimal bounding ellipsoid (OBE) algorithms for signal processing. All reported OBE algorithms are placed in a general framework which fruitfully demonstrates the relationship between the set-membership principles and least square error identification. Within this framework, flexible measures for adding explicit adaptation capability are formulated and demonstrated through simulation. Computational complexity analysis of OBE algorithms reveals that they are of O (m2) complexity per data sample with m the number of parameters identified, in spite of their well-known propensity toward highly selective updating. Two very different approaches are described for rendering a specific OBE algorithm, the set-membership weighted recursive least squares algorithm, of O (m) complexity. The first approach involves an algorithmic solution in which a suboptimal test for innovation is employed. The performance is demonstrated through simulation. The second method is an architectural approach in which complexity is reduced through parallel computation.

关键词： signal processing algorithms Samarium Least squares methods signal processing speech processing Adaptive signal processing Computational complexity Algorithm design and analysis Testing Technological innovation

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A new adaptive image contrast enhancement method

A new adaptive image contrast enhancement method

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Image and Video processing 1993

作者： Yu, Tian-Hu Mitra, S.K. Department of Electrical and Computer Engineering Signal and Image Processing Laboratory University of California Santa BarbaraCA93106 United States

In direct methods of contrast enhancement, a contrast measure is first defined, which is then modified by a mapping function to generate the pixel value of the enhanced image. Various mapping functions such as the square root function, the exponential function, etc., have been introduced for the contrast measure modification. However, these functions do not produce satisfactory contrast enhancement results and are usually sensitive to noise and digitization effects. In addition, they are computationally complex from the point of view of implementation. In this paper, we propose a simple polynomial mapping function for the contrast measure modification. The polynomial function is easy to implement on digital computers and provides very satisfactary contrast enhancement. We also introduce an adaptive clipping technique to control the dynamic range of the output image. © 1993 SPIE. All rights reserved.

关键词： Exponential functions

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ONE-BIT SPECTRAL-CORRELATION ALGORITHMS

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IEEE TRANSACTIONS ON signal processing 1993年第1期41卷 423-427页

作者： GARDNER, WA ROBERTS, RS Signal Processing Group Department of Electrical and Computer Engineering University of California Davis CA USA Los Alamos National Laboratory Los Alamos NM USA Signal Processing Group. Department of Electrical and Computer Engineering University of California Davis CA USA

A technique that greatly simplifies the computational complexity of digital cyclic spectral analysis algorithms is presented. The technique, which is based on Bussgang's theorem, replaces complex multiplications in spectral correlation operations with simple sign-change and data-multiplexing operations. Moreover, the technique is applicable to both time- and frequency-averaging algorithms. A simulation study that compares the computed results obtained using the new technique with results from standard time- and frequency-averaging algorithms shows that the new technique is very promising, particularly for frequency-averaging algorithms.

关键词： signal processing algorithms Frequency estimation Spectral analysis signal analysis Instruments signal processing Bandwidth Aging Phase measurement Laboratories

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Histogram-shape preserving algorithm for image enhancement

Histogram-shape preserving algorithm for image enhancement

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IEEE International Symposium on Circuits and Systems (ISCAS)

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

A new direct contrast enhancement algorithm is proposed. It can be used to enhance the contrast of an image without increasing the dynamic range of the pixel values. A distinctive property of the proposed method is that it yields results matching the characteristic of the human visual system. The histogram of the enhanced image has almost the same shape as that of the original image.< >

关键词： Image enhancement Dynamic range Pixel Histograms Shape Humans Visual system Displays Computational complexity signal processing

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Nonlinear filters for image sharpening and smoothing

Nonlinear filters for image sharpening and smoothing

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IEEE International Conference on Systems engineering

作者： Mitra Yu Signal and Image Processing Laboratory Department of Electrical & Computer Engineering University of California Santa Barbara CA USA

A general approach to the transform-magnitude-shaping-based image enhancement method is advanced. In the method, the magnitude of the input image transform is modified using a nonlinear mapping expressible as a power series, while its phase is kept invariant. The inverse transform of the modified image transform results in a sharpening or smoothing depending on the choice of the power series coefficients. Further improvement in the overall enhancement is achieved by a two-channel processing scheme which is implemented by applying different transform amplitude shaping methods to the low-frequency and high-frequency components. Examples the proposed enhancement method are included.< >

关键词： Filtering Image processing Transforms

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Leak monitoring system for gas pipelines

Leak monitoring system for gas pipelines

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

作者： I. Brodetsky M. Savic Electrical Computer and System Engineering Department Signal and Speech Research Laboratory Rensselaer Polytechnic Institute Troy NY USA

An approach and a solution to the continuous leak monitoring problem in underground gas pipelines are presented. This approach places permanent monitoring units along the pipeline. These units detect acoustic signals in the pipeline and discriminate leak sounds from other man-made or natural nonleak sounds that can occur. The system uses the kNN classifier as the detector with LPC (linear predictive coding) cepstrums as signal features. To increase system performance, pipeline effects on acoustic signals were taken into account during the classifier training phase. Each unit can detect 1/4-in-diameter leaks from a distance of 300 m, yielding 600 m as the maximum distance between units.< >

关键词： Monitoring Pipelines Acoustic signal detection Leak detection Linear predictive coding signal detection Neural networks Detectors Cepstrum System performance

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Application of QR decomposition-based least squares technique to improve air traffic control radar

Application of QR decomposition-based least squares techniqu...

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Midwest Symposium on Circuits and Systems (MWSCAS)

作者： T. Ogunfunmi Nam Ling Signal and Image Processing Laboratory (SIPL) Department of Electrical Engineering Santa Clara University Santa Clara CA USA Computer Systems and Parallel Processing Research Laboratory (CSPPRL) Department of Computer Engineering Santa Clara University Santa Clara CA USA

For real-time radar processing, it is very desirable to have an algorithm that does not assume restricted statistics of the input data and can be implemented for high-speed processing (without a high cost) to meet real-time requirements. We therefore apply the QR decomposition-based least-squares method for linear prediction to the problem of computing the reflection coefficients of a lattice predictor, instead of using the conventional Burg algorithm. We also propose a modified one-dimensional ring architecture for implementing the QR method of least-squares. The particular application considered in this case is that of surveillance radar systems for air traffic control.< >

关键词： Least squares methods Air traffic control Radar applications signal processing algorithms Radar signal processing Statistics Systolic arrays Radar imaging signal processing Surveillance

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