نتایج جستجو برای: wavelet spectrum

تعداد نتایج: 260401  

2012
Saket kumar

Spectrum has valuable resource in wireless communication. In wireless communication some spectrum is waste due to uses of cyclic prefix (cp) in FFT multicarrier sampling. In place of FFT used DFT and wavelet transform function for removal of cyclic prefix. Wavelet based OFDM, particularly using DWT and WPT-OFDM as situations for Fourierbased OFDM with the focus on impulse noise effects. We begi...

Journal: :Physical review. D, Particles and fields 1996
Huang Sarcevic Thews Wang

We present a novel method for studying the formation of a disoriented chiral condensate (DCC) in high-energy hadronic and heavy-ion collisions utilizing a discrete wavelet transformation. Due to its salient feature of space-scale locality, the discrete wavelet proves to be very eeective in probing physics simultaneously at diierent locations in phase space and at diierent scales. We show that t...

2004
JIN LEE

We consider semiparametric log periodogram regression estimation of memory parameter for the latent process in long memory stochastic volatility models. It is known that though widely used among researchers, the Geweke and Porter-Hudak (1983; GPH) LP estimator violates the Gaussian or Martingale assumption, which results in significant negative bias due to the existence of the spectrum of non-G...

2008
Guoming Xiong

We present the results of a wavelet-based approach to the study of the chaotic dynamics of a one dimensional model that shows a direct transition to spatiotemporal chaos. We find that the dynamics of this model in the spatiotemporally chaotic regime may be understood in terms of localized dynamics in both space and scale (wavenumber). A projection onto a Daubechies basis yields a good separatio...

2014
Abdesselem DAKHLI Chokri BEN AMAR

Genomic sequences allow to classify organisms into different categories and classes which have significant biological knowledge and can justify the evolution and identification of unknown organisms. Also they study mutual relations between organisms. The purpose of this classification is to study living organisms. Our system consists in three phases. The first phase is called transformation wic...

1994
Rainer von Sachs Kai Schneider

We consider wavelet estimation of the time–dependent (evolutionary) power spectrum of a locally stationary time series. Hereby, wavelets are used to provide an adaptive local smoothing of a short–time periodogram in the time–frequency plane. For this, in contrast to classical nonparametric (linear) approaches we use non–linear thresholding of the empirical wavelet coefficients. We show how thes...

2009
Le Thai Hoa

Fourier Transform and its tools have been applied popularly in many engineering applications. However, the Fourier Transform cannot analyze non-stationary, non-linear and intermittent signals with simultaneously time-frequency plane. Wavelet Transform have been invented recently to cope with limitations of the Fourier Transforms. This paper presents Continuous Wavelet Transform and its recent a...

Journal: :CoRR 2011
Lotfi Salhi Kaïs Ouni

This paper presents a new method on the use of the gammachirp auditory filter based on a continuous wavelet analysis. The gammachirp auditory filter is designed to provide a spectrum reflecting the spectral properties of the cochlea, which is responsible for frequency analysis in the human auditory system. The impulse response of the theoretical gammachirp auditory filter that has been develope...

2004
D. Maraun

In this paper, we present a detailed evaluation of cross wavelet analysis of bivariate time series. We develop a statistical test for zero wavelet coherency based on Monte Carlo simulations. If at least one of the two processes considered is Gaussian white noise, an approximative formula for the critical value can be utilized. In a second part, typical pitfalls of wavelet cross spectra and wave...

Journal: :CoRR 2010
Dilip S. Aldar

Spectrum sensing is the challenge for cognitive radio design and implementation, which allows the secondary user to access the primary bands without interference with primary users. Cognitive radios should decide on the best spectrum band to meet the Quality of service requirements over all available spectrum bands. This paper investigates the integrated centralized spectrum sensing techniques ...

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