Rapid development of new and ever expanding wireless applications and services, spectrum resources are facing huge demands. Currently, spectrum allotment is done by giving each new service with its own fixed frequency block. As more and more technologies are moving towards fully wireless, demand for spectrum is enhancing. In this context, a new technology, cognitive radio (CR) has been come out...

Abstract. In this paper, a novel scheme for the analysis of quad-trees in the discrete wavelet spectrum of a digital image is proposed. The scheme can be successfully applied to any zero-tree based image encoder, such as the embedded zero-tree wavelet (EZW) algorithm of Shapiro and set partitioning in hierarchical trees (SPIHT) by Said and Pearlman. Exceptionally high performance of the propose...

In this paper we study cyclical patterns by applying multivariate wavelet analysis. The wavelet covariance and wavelet correlation are defined and applied to the analysis of business cycles as an alternative to the traditional cross-spectrum analysis. The main findings for Slovenia are that there is a significant business cycle component in aggregate economic activity. Business cycles are asymm...

This paper proposes a novel ultra-high-speed directional relay using the wavelet transform. Two relay signals indicating traveling direction are composed of fault-induced voltage and current waves propagating along EHV/UHV transmission lines. Wavelet transform technique is employed to extract transient components from the relaying signals, and represent the transient component magnitude with wa...

The efficiency of all Zerotree coding algorithms relay on the "decaying spectrum" hypothesis: a wavelet coefficient within a certain frequency scale of a wavelet subband decomposition has a larger magnitude than all his descendants (coefficients situated in higher frequency scales having the same spatial orientation). The higher the percentage this hypothesis is satisfied, the better are the re...

A wavelet based model for propagation of optical pulses in nonlinear media is presented. We obtain an O(N) algorithm for linear propagation by replacing the wavelet-domain propagation operator by its Taylor series approximation. Nonlinear propagation is then achieved by adding the nonlinear term in mid-step in a method analogous to the split-step Fourier method. Using wavelets ooers the advanta...

It is shown that the wavelet correlation dimension is a very relevant quantity for the characterization of rough surfaces by remote sensing means. First, the concept of correlation length is generalized to surfaces with wide power spectrum. Second, it is demonstrated that, in the framework of the small-perturbation theory, the wavelet correlation dimension can be retrieved from a knowledge of t...

Image fusion is one of the important techniques to enhance image information of remote sensing. In order to adequately make use of all kinds of remote sensing images information such as Panchromatic and threeband multi-spectral images, a novel remote sensing image fusion scheme based on wavelet transform is proposed. The fusion of multispectral (MS) and panchromatic (PAN) images, with complemen...

We develop a method for spatio-spectral localization of harmonic data on a sphere and use it to interpret recent high-resolution global estimates of the gravity and topography of Venus in the context of geodynamical models. Our approach applies equally to the simple spatial windowing of harmonic data and to variable-length-scale analyses, which are analogous to a wavelet transform in the Cartes...

Abstract In this work, automatic detection and diagnosis of gear condition monitoring technique is presented. The vibration signals in time domain wereobtained from a fault simulator apparatus from a healthy gear and an induced faulty gear. These time domain signals were processed using Laplace and Morlet wavelet based enveloped power spectrum to detect the faults in gears. The vibration signal...