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Showing papers on "Impulse noise published in 2000"


01 Jan 2000
TL;DR: In this article, the powerline channel does not represent an additive white Gaussian noise (AWGN) environment; in the frequency range from some hundred kilohertz up to 20 MHz it is mostly dominated by narrow-band interference and impulsive noise.
Abstract: Opposite to many other communication channels the powerline channel does not represent an additive white Gaussian noise (AWGN) environment; in the frequency range from some hundred kilohertz up to 20 MHz it is mostly dominated by narrow-band interference and impulsive noise. After a basic classification of the different types of noise the properties of background noise and narrow-band interference are discussed. Spectral analysis and time domain analysis of impulse noise gives some figures of the power spectral density as well as distributions of L noise f , I impulse noise ; J , . . .

199 citations


Journal ArticleDOI
TL;DR: The new fast nonlinear adaptive filtering algorithms called the least mean M-estimate (LMM) and transform domain LMM (TLMM) algorithms are derived and Simulation results show that they are robust to impulsive noise in the desired and input signals with an arithmetic complexity of order O(N).
Abstract: This paper proposes two gradient-based adaptive algorithms, called the least mean M estimate and the transform domain least mean M-estimate (TLMM) algorithms, for robust adaptive filtering in impulse noise. A robust M-estimator is used as the objective function to suppress the adverse effects of impulse noise on the filter weights. They have a computational complexity of order O(N) and can be viewed, respectively, as the generalization of the least mean square and the transform-domain least mean square algorithms. A robust method fur estimating the required thresholds in the M-estimator is also given. Simulation results show that the TLMM algorithm, in particular, is more robust and effective than other commonly used algorithms in suppressing the adverse effects of the impulses.

171 citations


Journal ArticleDOI
TL;DR: Simulation results showed that the RLM algorithm performs better than the conventional RLS, NRLS, and the OSFKF algorithms when the desired and input signals are corrupted by impulses.
Abstract: This paper proposes a recursive least M-estimate (RLM) algorithm for robust adaptive filtering in impulse noise. It employs an M-estimate cost function, which is able to suppress the effect of impulses on the filter weights. Simulation results showed that the RLM algorithm performs better than the conventional RLS, NRLS, and the OSFKF algorithms when the desired and input signals are corrupted by impulses. Its initial convergence, steady-state error, computational complexity, and robustness to sudden system change are comparable to the conventional RLS algorithm in the presence of Gaussian noise alone.

104 citations


Proceedings ArticleDOI
24 Sep 2000
TL;DR: A modulation/coding scheme combining M-FSK modulation with diversity and coding to make the transmission robust against permanent frequency disturbances and impulse noise is described.
Abstract: We describe a modulation/coding scheme combining M-FSK modulation with diversity and coding to make the transmission robust against permanent frequency disturbances and impulse noise. We use simple non-coherent detection. The scheme can be considered as a form of coded frequency hopping and is easy extendable. We give a generalized construction procedure for new trellis codes of various rates and constraint lengths using our previously published technique of distance preserving mapping. Maximum likelihood decoding of these codes can follow naturally.

68 citations


Journal ArticleDOI
TL;DR: Simulation results show that a rank-based detector is able to approach the performance of the computationally intensive LO and LOR detectors across a range of values for for /spl alpha/.
Abstract: Impulsive interference poses a challenge to conventional detection techniques. The /spl alpha/-stable distribution, while sometimes providing a good model for impulsive interference, has proven to be no exception. Some of these difficulties have motivated the investigation and development of computationally tractable, locally suboptimum correlation, and rank correlation detectors for signals embedded in impulsive interference modeled as a symmetric /spl alpha/-stable process. The performance of some of these detectors is evaluated and compared with that of the locally optimum (LO), locally optimum rank (LOR), matched filter, and Cauchy detectors. Simulation results show that a rank-based detector is able to approach the performance of the computationally intensive LO and LOR detectors across a range of values for for /spl alpha/.

57 citations


Proceedings ArticleDOI
25 Jun 2000
TL;DR: The application of coded modulation for power line communications is discussed, combining M-FSK with permutation codes to include frequency and time diversity, which makes the transmissions robust against permanent frequency disturbances and impulse noise.
Abstract: We discuss the application of coded modulation for power line communications. We combine M-FSK with permutation codes to include frequency and time diversity. This makes the transmissions robust against permanent frequency disturbances and impulse noise. The scheme is applicable to any frequency range.

54 citations


Proceedings ArticleDOI
05 Jun 2000
TL;DR: A generalized framework for median filtering based on a switching scheme, called multi-state median (MSM) filter, is proposed, which is equivalent to an adaptive CWM filter with a space varying center weight which is dependent on local signal characteristics.
Abstract: Images are often corrupted by impulse noise due to a noisy sensor or channel transmission errors. The goal of removing impulse noise is to suppress the noise while preserving the integrity of edge and detail information associated with the original image. In this paper, a generalized framework for median filtering based on a switching scheme, called multi-state median (MSM) filter, is proposed. By using a simple thresholding operation, the output of the proposed MSM filter is adaptively switched among those of a group of centre weighted median (CWM) filters having different centre weights. As a result, the MSM filter is equivalent to an adaptive CWM filter with a space varying center weight which is dependent on local signal characteristics. The effectiveness in noise suppression and detail preservation of the proposed filtering technique has been evaluated by extensive simulations, showing superior performance to other median based filters.

49 citations


Patent
Thomas J. Kolze1
13 Dec 2000
TL;DR: In this paper, the error rate performance of short data packets in cable modems in an impulsive noise environment is improved by initializing a cable modem on more than one channel.
Abstract: A single carrier cable modem can be initialized on multiple channels. By initializing a cable modem on more than one channel, the error rate performance of short data packets in cable modems in an impulsive noise environment is improved. The advantage of low symbol rate transmission for short packets in an impulse noise environment is achieved without sacrificing burst capacity at a cable modem and without the complexity of transmitting multiple symbol waveforms simultaneously at a cable modem.

46 citations


Journal ArticleDOI
TL;DR: The intense MRI acoustic impulse noise generated by the 4.7 T experimental MRI system may cause masking of stimuli used in fMRI of the auditory cortex, reduce the hearing acuity of experimental animals and present a risk for unprotected human ears.
Abstract: High intensity acoustic noise is an undesirable side-effect in magnetic resonance imaging (MRI) that can cause discomfort and hearing loss in patients and may be an impediment in functional MRI (fMRI) studies of the auditory system. Experimental MRI systems with high magnetic field strengths may generate acoustic noise of higher sound pressure levels (SPLs) than conventional 1.0 and 1.5 T clinical systems. We measured the SPL and spectral content of the acoustic noise generated by the Bruker Biospect 47/40 4.7 T experimental MRI system during scanning sequences commonly used in animal testing. Each sequence generated acoustic noise of high SPL, rapid pulse rates, amplitude-modulated pulse envelopes and multi-peaked spectra. The rapid acquisition with enhancement sequence with a 0.25 mm slice thickness generated SPLs of up to 129 dB peak SPL and 130 dB (A). Fourier analysis of the spectral content of the acoustic noise generated by each MRI sequence showed a wide band of acoustic energy with spectral peaks from 0.2-5 kHz. The intense MRI acoustic impulse noise generated by the 4.7 T system may cause masking of stimuli used in fMRI of the auditory cortex, reduce the hearing acuity of experimental animals and present a risk for unprotected human ears.

43 citations


Book ChapterDOI
01 Jan 2000
TL;DR: Fuzzy rule-based image processing technologies for noise reduction and edge extraction are described, and fuzzy reasoning part is designed optimally by expressing the system as a nonlinear function of multiple local characteristics of signals.
Abstract: Fuzzy rule-based image processing technologies for noise reduction and edge extraction are described. Here, two types of noises are considered in noise reduction, namely white Gaussian noise and impulsive noise. Fuzzy rules are applied in order to consider the nonstationarity and uncertainty of signals. Moreover, the fuzzy reasoning part is designed optimally by expressing the system as a nonlinear function of multiple local characteristics of signals, and by setting the nonlinear function so that the mean square error of the output is the minimum for some training image data. Accordingly, the membership function and the rules are automatically designed from this optimization. Computer simulations verify the effective performance of this image processing technology.

41 citations


Proceedings ArticleDOI
15 May 2000
TL;DR: An investigation of the properties of vehicular DC-lines for the purpose of data communication and the aim is to model the transfer channel that represents these lines.
Abstract: This paper presents an investigation of the properties of vehicular DC-lines for the purpose of data communication. In doing so, the aim is to model the transfer channel that represents these lines. The basis for this investigation is established by measurements of battery lines in vehicles. First various line segments are regarded without disturbance. In a second step the existing interference is investigated. With particular interest the impulsive noise is regarded. Important is the possibility to calculate its random occurrence by a statistical process called Poisson process. The present results are the basis for further investigations of data communication over DC-lines in cars.

Proceedings ArticleDOI
17 Dec 2000
TL;DR: Simulation results for moderate Signal-to-Noise-Ratios are reported and samples corrupted by impulse noise are reconstructed by using redundancy of the guard band in the frequency domain.
Abstract: Orthogonal frequency division multiplexing (OFDM) has received a considerable attention for realisation of high-speed communication systems. Digital data is transmitted on N subchannels simultaneously, and the frequency responses of the subchannels are overlapping and orthogonal. To avoid interference between adjacent channels, the guard interval in frequency domain is used. Impulse noise is bursty, high amplitude, low probability noise, taking the form of the time domain impulse. Such impulses of very short duration contain spectral components on all subchannels, and thus impact the decision of symbols transmitted on all subcarriers. The receiver detects the presence and the position of the impulse within the OFDM symbol by combining the power calculation in time and frequency domain. Samples corrupted by impulse noise are reconstructed by using redundancy of the guard band in the frequency domain. Simulation results for moderate Signal-to-Noise-Ratios are reported.

Journal ArticleDOI
TL;DR: In this paper, the authors derived an expression for the probability of error for a WPDM scheme in the presence of both impulsive and Gaussian noise sources and demonstrate that WPDMs can provide greater immunity to impulsive noise than both a time-division multiplexing (TDMM) and an orthogonal frequency-division (OFDM) scheme.
Abstract: Wavelet packet-division multiplexing (WPDM) is a high-capacity, flexible, and robust multiple-signal transmission technique in which the message signals are waveform coded onto wavelet packet basis functions for transmission. We derive an expression for the probability of error for a WPDM scheme in the presence of both impulsive and Gaussian noise sources and demonstrate that WPDM can provide greater immunity to impulsive noise than both a time-division multiplexing scheme and an orthogonal frequency-division multiplexing scheme.

Proceedings ArticleDOI
01 Sep 2000
TL;DR: Simulations show that a 3dB improvement in SNR over the classical TSC scheme is obtained for a global rate of 8.2 transmitted bits per source sample and small BSC crossover probability.
Abstract: In this paper, a spectral interpolation coder (SIC) and decoder are investigated for simultaneous source coding and impulse noise cancellation. For simplicity of the analysis, we restrict ourselves to the framework of scalar quantization of a memoryless gaussian source to be transmitted over binary symmetric channel (BSC). Our approach is to make a carefully designed interpolation of the data in the spectral domain prior to quantization and transmission. The SIC decoder then exploits the properties of SIC codes in order to analyse, detect and correct (or reduce) erroneous data. A nice feature of this procedure is that the decoder deals simultaneously with the quantization noise and impulse channel noise; therefore it is able to reduce distortion introduced not only by the transmission channels errors but also by the quantizer. A comparaison study is also investigated in this paper: Simulations show that we obtain a 3dB improvement in SNR over the classical TSC scheme for a global rate of 8.2 transmitted bits per source sample and small BSC crossover probability.

Journal ArticleDOI
TL;DR: A robust class of estimators for the parameters of a deterministic signal in impulsive noise has the structure of the maximum likelihood estimator (MLE) but has an extra degree of freedom: the choice of a nonlinear function (which is different from the score function suggested by the MLE) that can be adjusted to improve robustness.
Abstract: This paper presents a robust class of estimators for the parameters of a deterministic signal in impulsive noise. The proposed technique has the structure of the maximum likelihood estimator (MLE) but has an extra degree of freedom: the choice of a nonlinear function (which is different from the score function suggested by the MLE) that can be adjusted to improve robustness. The effect of this nonlinear function is studied analytically via an asymptotic performance analysis. We investigate the covariance of the estimates and the loss of efficiency induced by nonoptimal choices of the nonlinear function, giving special attention to the case of /spl alpha/-stable noise. Finally, we apply the theoretical results to the problem of estimating the parameters of a sinusoidal signal in impulsive noise.

Patent
18 Dec 2000
TL;DR: In this paper, an impulse noise reducer detects impulse noise in an audio signal by detecting and smoothing the high-frequency amplitude of the audio signal, attenuating the non-smoothed amplitude according to the smoothed amplitude, and comparing the attenuated amplitude with a threshold.
Abstract: An impulse noise reducer detects impulse noise in an audio signal by detecting and smoothing the high-frequency amplitude of the audio signal, attenuating the non-smoothed amplitude according to the smoothed amplitude, and comparing the attenuated amplitude with a threshold. Impulse noise is discriminated from high-frequency audio components because the latter tend to occur in longer-lasting bursts and are therefore attenuated more strongly. The impulse noise reducer is simplified because it does not have to perform intermediate-frequency signal processing, and its sensitivity is not affected by adjacent-channel signals because these signals are substantially absent from the audio signal. The impulse noise reducer can be implemented by digital signal processing, and is suitable for use in a medium-wave AM audio broadcast receiver.

Journal ArticleDOI
TL;DR: Simulation demonstrates that the new minimax robust two-dimensional beamforming is able to solve tight sources, as well as to give high accuracy estimates for rapidly moving sources, and the new estimates show the strong resistance to heavy-tailed distribution noises.

Journal ArticleDOI
TL;DR: Numerical and simulation studies under finite-data-record system adaptation show significant improvement in bit-error-rate performance over the conventional linear minimum variance-distortionless-response (MVDR) SS receiver or conventional MVDR filtering preceded by vector adaptive chip-based nonlinear processing.
Abstract: The problem under consideration is the adaptive reception of a multipath direct-sequence spread-spectrum (SS) signal in the presence of unknown correlated SS interference and additive impulsive noise. An SS receiver structure is proposed that consists of a vector of adaptive chip-based Hampel nonlinearities followed by an adaptive auxiliary-vector linear tap-weight filter. The nonlinear receiver front end adapts itself to the unknown prevailing noise environment providing robust performance over a wide range of underlying noise distributions. The adaptive auxiliary-vector linear tap-weight filter allows rapid SS interference suppression with a limited data record. Numerical and simulation studies under finite-data-record system adaptation show significant improvement in bit-error-rate performance over the conventional linear minimum variance-distortionless-response (MVDR) SS receiver or conventional MVDR filtering preceded by vector adaptive chip-based nonlinear processing.

Book ChapterDOI
Eduardo Abreu1
08 Sep 2000
TL;DR: This chapter presents the signal-dependent rank-ordering-mean (SD-ROM) method for the removal of impulse noise from image data, in which the filtering operation is conditioned on the rank-ordered differences, defined as the differences between the input pixel and the remaining rank- ordered pixels in a sliding window.
Abstract: Publisher Summary This chapter presents the signal-dependent rank-ordered-mean (SD-ROM) method for the removal of impulse noise from image data, in which the filtering operation is conditioned on the rank-ordered differences, defined as the differences between the input pixel and the remaining rank-ordered pixels in a sliding window. The chapter discusses two algorithms—one based on a simple detection-estimation strategy involving thresholds, and the other incorporating fuzzy rules. The strategies for the design of the weighting coefficients are presented in the algorithm incorporating fuzzy rules, for recursive and non-recursive implementation, including a least-squares derivation for the non-recursive case, which leads to a close form expression for the optimal weighting coefficients. This chapter also presents computer simulation examples to illustrate the effectiveness of the SD-ROM method using several distinct noise types, including impulsive, Gaussian, and mixed impulsive and Gaussian. Finally, it presents a simple algorithm for restoration of images corrupted by streaks, based on the SD-ROM approach.

Proceedings ArticleDOI
01 Sep 2000
TL;DR: The new fast nonlinear adaptive filtering algorithms called the least mean M-estimate (LMM) and transform domain LMM (TLMM) algorithms are derived and Simulation results show that they are robust to impulsive noise in the desired and input signals with an arithmetic complexity of order O(N).
Abstract: Adaptive filters with suitable nonlinear devices are very effective in suppressing the adverse effect due to impulse noise. In a previous work, the authors have proposed a new class of nonlinear adaptive filters using the concept of robust statistics [1,2]. The robust M-estimator is used as the objective function, instead of the mean square errors, to suppress the impulse noise. The optimal coefficient vector for such nonlinear filter is governed by a normal equation which can be solved by a recursive least squares like algorithm with O(N2) arithmetic complexity, where N is the length of the adaptive filter. In this paper, we generalize the robust statistic concept to least mean square (LMS) and transform domain LMS algorithms. The new fast nonlinear adaptive filtering algorithms called the least mean M-estimate (LMM) and transform domain LMM (TLMM) algorithms are derived. Simulation results show that they are robust to impulsive noise in the desired and input signals with an arithmetic complexity of order O(N).

Journal ArticleDOI
TL;DR: The first proposed multichannel filter is rather highly effective for Gaussian and Uniform noise removal in preserving good edges and robust to Gaussian, Uniform, Impulse noise, and Gaussian noise mixed with outliers.

Journal ArticleDOI
TL;DR: AWFM is an extension of weighted fuzzy mean (WFM) filter by linking a fuzzy detector and a dynamic selection procedure to W FM in order to overcome the drawback of WFM in fine signal preservation.

Proceedings ArticleDOI
05 Jun 2000
TL;DR: A novel noise adaptive soft-switching median (NASM) filter is proposed to effectively address the above-mentioned issues and achieve much improved filtering performance in terms of efficiency in removing impulse noise and robustness against noise density variations.
Abstract: We observed that certain fundamental concerns commonly exist in some state-of-the-art switching-based median filters: (i) fixed thresholding for the pre-assumed noise density, (ii) the noise decision accuracy at high density impulse noise, and (iii) the filtering scheme adopted in response to pixel characteristic type identified. In this paper, we propose a novel noise adaptive soft-switching median (NASM) filter to effectively address the above-mentioned issues and achieve much improved filtering performance in terms of efficiency in removing impulse noise and robustness against noise density variations. Experimental results also reveal that the performance of our NASM filter is fairly close to that of ideal-switching median filter.

Proceedings ArticleDOI
10 Sep 2000
TL;DR: A novel adaptive filter based on the impulse rejecting mechanism, where detected impulses are filtered and noise-free pixels are left unaltered, which consistently performs well in suppressing both types of impulse noise while still employing a simple structure.
Abstract: This paper proposes a novel adaptive filter based on the impulse rejecting mechanism, where detected impulses are filtered and noise-free pixels are left unaltered. Previous impulse detection strategies based on thresholding operations tend to work well for large, fixed-valued impulses but poorly for random-valued impulse noise, or vice versa. The objective of this work is to utilize the center weighted median (CWM) filters with variable center weights to define a more general operator, which forms estimates according to the differences defined between the outputs of CWM filters and the current pixel in consideration. As compared with existing schemes, the proposed filter consistently performs well in suppressing both types of impulse noise while still employing a simple structure. Better performance has been achieved by the new filter in restoring a variety of images corrupted with different noise ratios.

Proceedings ArticleDOI
04 Dec 2000
TL;DR: In this article, the authors present techniques for characterization of power lines in Singapore power distribution network and methodologies to extract necessary information from the measured data in 1 MHz to 10 MHz frequency range.
Abstract: This paper presents techniques for characterization of power lines in Singapore power distribution network and methodologies to extract necessary information from the measured data in 1 MHz to 10 MHz frequency range. Measurements are made on the noises in actual residential power lines, which are generated from some typical electrical apparatuses used in an ordinary home. The equipment and locations used to obtain our measurements are described. The results of impulse noise measurements in typical residential power lines are presented. Statistical analyses of the measurements are presented in the form of amplitude probability distributions, pulse duration distributions, and interarrival time distributions. From the results obtained so far, it is observed that the noise and signal attenuation of power distribution lines vary with frequency, time and location. These are caused by the rather dynamic nature of power lines and their connected loads that are changing all the time.

Patent
13 Dec 2000
TL;DR: In this paper, a linear block interleaver is used to combine multiple signaling constellations into n-tone combinations, such that noise energy present in at least one of the ntone combinations is spread among each of the multiple tones.
Abstract: A discrete multi-tone (DMT) digital subscriber line (DSL) communication device employs a linear block interleaver for mathematically combining multiple tones into n-tone combinations in order to efficiently suppress or eliminate correlated noise or impulse noise generated in the communication channel. In architecture, the linear block interleaver includes logic configured to combine multiple signaling constellations into n-tone combinations. The multiple constellations are mathematically combined such that noise energy present in at least one of the n-tone combinations is spread among each of the multiple tones, thus reducing the energy of the noise on each of the multiple tones.

Patent
David Zhou1, Francois Charette1, Keng D. Hsueh1, Vy Tran1, Hsiao-an Hsieh1 
30 Aug 2000
TL;DR: In this article, a combined noise detector picks up a combined signal, which includes both background noise and the unwanted noise generated by the source, and a noise separation synthesis device filters both signals to generate a coherent unwanted noise signal from the combined noise signal.
Abstract: An apparatus for detecting unwanted noise includes a reference sensor that generates a reference signal in response to stimulation by a source. A combined noise detector picks up a combined noise signal, which includes both background noise and the unwanted noise generated by the source. A noise separation synthesis device filters both signals to generate a coherent unwanted noise signal from the combined noise signal as a function of the reference signal generated by the reference sensor. A comparator determines the presence of unwanted noise by calculating the Kurtosis value of the coherent unwanted noise signal.

Proceedings ArticleDOI
05 Jun 2000
TL;DR: The performance of MBFE is studied experimentally on a connected-digits recognition task in several additive noise conditions and is compared to that of a state-of-the-art implementation of nonlinear spectral subtraction.
Abstract: In this paper, a new feature enhancement algorithm called model-based feature enhancement (MBFE) is introduced for noise robust speech recognition. In MBFE, statistical models (i.e., Gaussian HMM's) of the clean speech feature vectors and of the perturbing noise feature vectors are used to construct the optimal MMSE estimator of the clean speech feature vectors. The estimated clean speech features are then fed to a recognizer. The performance of MBFE is studied experimentally on a connected-digits recognition task in several additive noise conditions (synthetic white and impulsive noise, car noise, and machine tool noise are considered). The performance of MBFE is also compared to that of a state-of-the-art implementation of nonlinear spectral subtraction.

Proceedings ArticleDOI
27 Mar 2000
TL;DR: A new algorithm for visual reconstruction of digital images which have been corrupted by mixed noise is introduced from an image hypergraph model and a combinatorial definition of noisy data is introduced.
Abstract: This paper introduces a new algorithm for visual reconstruction of digital images which have been corrupted by mixed noise. From an image hypergraph model we introduce a combinatorial definition of noisy data. A detection procedure is used to classify the hyperedges either as noisy or clean data. Similar to other techniques, the proposed algorithm uses then an estimation procedure to remove the effects of the noise from image data. Numerical simulations demonstrate that this algorithm suppress the effect of the noise while preserving the edges with a high degree of accuracy at a relatively low computational cost.

Proceedings ArticleDOI
10 Sep 2000
TL;DR: A method for choosing the thresholds based on a statistical characterization of an input image that approximates the histogram of an image with a weighted sum of Gaussian distributions is proposed.
Abstract: The signal-dependent rank order mean (SD-ROM) filter is effective at removing high levels of impulse noise from 2-D scalar-valued signals. Excellent results have been presented for both a two-state and a multi-state version of the filter. However, implementation of the two-state SD-ROM filter requires the selection of a set of threshold values. We propose a method for choosing the thresholds based on a statistical characterization of an input image. The method approximates the histogram of an image with a weighted sum of Gaussian distributions. Using the statistical model and the input distributions, the likelihood of correctly identifying impulses is estimated as a function of the thresholds. By maximizing the likelihood of correct detection, optimal thresholds are predicted. The performance of the algorithm using the predicted thresholds is compared to the optimal performance found using a brute-force search.