Topic
White noise
About: White noise is a research topic. Over the lifetime, 16496 publications have been published within this topic receiving 318633 citations.
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01 Jan 1987
TL;DR: In this article, the in-phase and quadrature components of the clutter echoes have been modelled to give a Weibull probability density function (PDF) of the amplitude and a uniform PDF of the phase.
Abstract: The paper deals with the problem of radar detection of a target echo embedded in Weibull clutter and white Gaussian noise (WGN). Relevant features of the paper, with respect to previous papers on the same subject, refer to the coherent nature of the Weibull process (that modelling the clutter) and of the processing chain. In more detail, the in-phase and quadrature components of the clutter echoes have been modelled to give a Weibull probability density function (PDF) of the amplitude and a uniform PDF of the phase. Any shape of the correlation function among consecutive clutter samples is also allowed in the model. The so called 'coherent Weibull clutter' (CWC) introduced in the paper represents a suitable generalisation of the conventional ?coherent Gaussian clutter? (CGC). The processing chain is also coherent, i.e. it operates on the in-phase and quadrature components of the signals. To derive a suitable processing scheme, we resort to the general theory of radar detection which applies to any type of PDF and autocorrelation function (ACF) of the target and clutter. Briefly, it is found that the processing scheme is based on two nonlinear estimators of the clutter samples in the two alternative hypotheses (i.e. H0 and H1 the fully fledged architecture being discussed in the paper. The detection processor turns out to be a suitable generalisation of that concerning the CGC case. A new family of processing schemes is derived in accordance with the statistical model assumed for the useful target. The following cases are covered: target known a priori, Swerling 0, 1 and 2 models, and partially fluctuating target. Attention is also paid to the interesting case of a target modelled as a coherent Weibull process. The detection of such a target against white Gaussian noise is worked out. The detection performance of the a
88 citations
TL;DR: A noise source model, consisting of a pulse sequence at random times with memory, which could be useful to describe physical and biological systems where some delay is present, is presented and it is found that the time behavior of the illness depends on the noise parameters.
Abstract: A noise source model, consisting of a pulse sequence at random times with memory, is presented. By varying the memory we can obtain variable randomness of the stochastic process. The delay time between pulses, i.e. the noise memory, produces different kinds of correlated noise ranging from white noise, without delay, to quasi-periodical process, with delay close to the average period of the pulses. The spectral density is calculated. This type of noise could be useful to describe physical and biological systems where some delay is present. In particular it could be useful in population dynamics. A simple dynamical model for epidemiological infection with this noise source is presented. We find that the time behavior of the illness depends on the noise parameters. Specifically the amplitude and the memory of the noise affect the number of infected people.
88 citations
TL;DR: In this article, a Bayesian combination approach for multivariate predictive densities is proposed, which relies upon a distributional state space representation of the combination weights, with a particular focus on weight dynamics driven by the past performance of the predictive density and the use of learning mechanisms.
88 citations
TL;DR: In this paper, the effects of source finiteness, crustal wave propagation, and site response upon recorded strong ground motions from the 1989 Loma Prieta earthquake were assessed using band limited white noise (BLWN) with random vibration theory.
Abstract: The objective of this study is to assess the effects of source finiteness, crustal wave propagation, and site response upon recorded strong ground motions from the 1989 Loma Prieta earthquake. Our analysis uses band limited white noise (BLWN) with random vibration theory (RVT) to produce site‐specific estimates of peak acceleration and response spectral ordinates for both a point‐source and finite‐source model. Effects of nonlinear soil response are modeled through an equivalent‐linear approach. The point‐source model additionally accommodates crustal propagation effects in terms of direct‐plus‐postcritical reflections.
88 citations
TL;DR: The authors present a novel technique for the detection and localization of multiple sources in the presence of noise with unknown and arbitrary covariance based on Rissanen's minimum description length (MDL) principle for model selection.
Abstract: The authors present a novel technique for the detection and localization of multiple sources in the presence of noise with unknown and arbitrary covariance. The technique is applicable to coherent and noncoherent signals and to arbitrary array geometry and is based on Rissanen's minimum description length (MDL) principle (1989) for model selection. Its computational load is comparable to that of analogous techniques for white noise. Simulation results demonstrating the performance of this technique are included. >
88 citations