The computation of power spectra, cross spectra, coherence, and bispectra of various types of geophysical raildom processes is part of the established routine. Since it is routine, some of the standard procedures need to be examined rather carefully to be certain that the assumptions behind the procedures are applicable to the data on hand. The basic criteria for a particular method are its res...

We present two related techniques to measure the two-point correlation function and the power spectrum with edge correction in any spatial dimensions. The underlying algorithm uses fast Fourier transforms for calculating the two-point function with an heuristically weighted edge corrected estimator. Once the correlation function is measured, we estimate the power spectrum via numerical integrat...

We present a method of measuring galaxy power spectrum based on the multiresolution analysis of the discrete wavelet transformation (DWT). Besides the technical advantages of the computational feasibility for data sets with large volume and complex geometry, the DWT scale-by-scale decomposition provides a physical insight into the covariance matrix of the cosmic mass field. Since the DWT repres...

Estimations of scattering parameters, such as average scatterer diameter, from rf signals backscattered from random media (tissues) are made from the frequency dependence of the rf signal. The frequency dependence of the rf signal backscattered from the medium is seen in the normalized power spectrum. The normalized power spectrum is found by taking the squared magnitude of the Fourier transfor...

We are concern about a conjecture proposed in the middle of the seventies by Hellesseth in the framework of maximal sequences and theirs crosscorrelations. The conjecture claims the existence of a zero outphase Fourier coefficient. We give some divisibility properties in this direction. 1. Two conjectures of Helleseth Let L be a finite field of order q > 2 and characteristic p. Let μ be the can...

In Orthogonal Frequency Division Multiplexing (OFDM) carriers are orthogonally related and hence no guard band is necessary like in Frequency Division Multiplexing (FDM). So spectrums of users can overlap which enhances the spectrum efficiency of the network. In this thesis one of the main concern of OFDM, inter carrier interference (ICI) is considered using different window functions in freque...

Based on the numerical representations by T basic vectors of a symbolic sequence consisting of T symbols, first, we prove mathematical that the total Fourier spectrum of the sequence is the square of the length of the sequence. In the meantime, we define the indicator sequences vector. Using the orthogonal or row orthogonal transformations of the indicator sequences vector, we construct some sp...

An alternative code-division multiple-access (CDMA) scheme to spread spectrum (SS), called spread time (ST) is proposed for badlimited multiple-access channels. ST-CDMA can be considered the be-frequency dual of SS-CDMA. In ST-GDMA pslendsraodan (PN) sequences are assigned to each user, and the Fourier tcrursf@rm of the transmitted pulse for a given user is d&mined by modulating the phase of th...

Self potential (SP) method is a passive method that involves measurements of naturally occurring potentials, commonly associated with the weathering of sulfides ore bodies. Energy spectrum (power spectrum) method developed primarily for gravity and magnetic data have been adapted to electrical SP data. In case of SP data analysis, energy is taken as the square of the Fourier amplitude spectrum ...

We report line-by-line control of a coherent discrete spectrum (Raman sidebands) with a frequency spacing of 10.6 THz that is produced by an adiabatic Raman process. We show that the spectral phase of the Raman sidebands is finely controlled to the target (flat relative-spectral-phase). This is achieved by employing a combination of a spatial phase controller and a spectral interferometer, whic...