Topic
Noise measurement
About: Noise measurement is a research topic. Over the lifetime, 19776 publications have been published within this topic receiving 308180 citations.
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Papers
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TL;DR: A mathematically tractable and accurate model of narrowband power line noise based on experimental measurements is introduced, expressed as a Gaussian process whose instantaneous variance is a periodic time function.
Abstract: This manuscript introduces a mathematically tractable and accurate model of narrowband power line noise based on experimental measurements. In this paper, the noise is expressed as a Gaussian process whose instantaneous variance is a periodic time function. With this assumption and representation, the cyclostationary features of power line noise can be described in close form. The periodic function that represents the variance is then approximated with a small number of parameters. The noise waveform generated with this model shows good agreement with that of actually measured noise. Noise waveforms generated by different models are also compared with that of the proposed model.
300 citations
TL;DR: In this article, a discontinuous projection based adaptive robust controller (ARC) is proposed to guarantee a prescribed transient performance and final tracking accuracy in general, while achieving asymptotic tracking in the presence of parametric uncertainties.
Abstract: This paper studies the high performance robust motion control of an epoxy core linear motor, which has negligible electrical dynamics due to the fast response of the electrical subsystem. A discontinuous projection based adaptive robust controller (ARC) is first constructed. The controller theoretically guarantees a prescribed transient performance and final tracking accuracy in general, while achieving asymptotic tracking in the presence of parametric uncertainties. A desired compensation ARC scheme is then presented, in which the regressor is calculated using the reference trajectory information only. The resulting controller has several implementation advantages such as less online computation time, reduced effect of measurement noise, a separation of robust control design from parameter adaptation, and a faster adaptation rate. Both schemes are implemented and compared on an epoxy core linear motor. Extensive comparative experimental results are presented to illustrate the effectiveness and the achievable control performance of the two ARC designs.
299 citations
TL;DR: In this paper, the spectral analysis using least squares (LS) is further developed to remove any undesired influence on the spectrum, which can be used for irregularly spaced as well as equidistantly spaced data.
Abstract: The concept of spectral analysis using least-squares is further developed to remove any undesired influence on the spectrum. The influence of such a ‘systematic noise’ can be eliminated without the necessity of knowing the magnitudes of the noise constituents. The technique can be used for irregularly spaced as well as equidistantly spaced data. The response to random noise is found to be constant in the frequency domain and its expected level is derived. Presence of random noise in the analyzed time series is shown to transform the spectrum merely linearly. Examples of applications of the technique are presented.
298 citations
TL;DR: In this paper, the power spectral density of the interferometric noise and its impact on system performance as a function of both the magnitude and number of reflections at connectors and splices were calculated.
Abstract: Large power penalties and bit-error-rate floors have been observed in some Gb/s systems using distributed feedback (DFB) lasers, which could be attributed to interferometric conversion of laser phase noise to intensity noise by multiple reflections at connectors and splices. The authors calculated the power spectral density of the interferometric noise and its impact on system performance as a function of both the magnitude and number of reflections, and they compare the theoretical predictions with experimental results. Their studies indicate that connectors and splices with return losses of more than about 25 dB are required for the reliable operation of Gb/s fiber transmission systems, even if optical isolators are used. >
296 citations
TL;DR: A decision-based, signal-adaptive median filtering algorithm for removal of impulse noise, which achieves accurate noise detection and high SNR measures without smearing the fine details and edges in the image.
Abstract: We propose a decision-based, signal-adaptive median filtering algorithm for removal of impulse noise. Our algorithm achieves accurate noise detection and high SNR measures without smearing the fine details and edges in the image. The notion of homogeneity level is defined for pixel values based on their global and local statistical properties. The cooccurrence matrix technique is used to represent the correlations between a pixel and its neighbors, and to derive the upper and lower bound of the homogeneity level. Noise detection is performed at two stages: noise candidates are first selected using the homogeneity level, and then a refining process follows to eliminate false detections. The noise detection scheme does not use a quantitative decision measure, but uses qualitative structural information, and it is not subject to burdensome computations for optimization of the threshold values. Empirical results indicate that our scheme performs significantly better than other median filters, in terms of noise suppression and detail preservation.
290 citations