We describe and compare two types of microwave sky simulations which are good for small angular scales. The first type uses expansions in spherical harmonics, and the second one is based on plane waves and the Fast Fourier Transform. The angular power spectrum is extracted from maps corresponding to both types of simulations, and the resulting spectra are appropriately compared. In this way, th...

To replace the film recording aspect of performing optical correlation, conventional real-time joint-transform correlation (JTC) optical systems make use of a spatial light modulator (SLM) located in the Fourier plane to record the joint-transform power spectrum (JPS) to achieve real-time processing. The use of an SLM in the Fourier plane, however, is a major drawback in these systems because S...

Analysis of both pulse timing and pulse shape variations of the isolated pulsar PSR B1828-11 shows highly correlated and strong Fourier power at periods ≃ 1000, 500, 250, and 167 d (Stairs et al. 2000). The only description based on a free precession of star’s rigid crust coupled to the magnetic dipole torque, explains the 500component, as the fundamental Fourier frequency, with its harmonic 25...

It is well known that the high frequency components during QRS complex may relate with the scattered myocardial damages such as the focal necrosis. However, the time-frequency power spectrum limited in QRS can be hardly measured by use of the conventional fast Fourier transform (FFT) based algorithm. In contrast to the FFT, the wavelet transform (WT) has time-widths adapted to each frequency as...

We discuss a new convenient way to study periodical patterns in primary structures of biopolymers which appeared recently. For the sequence of a biopolymer the symbolic correlation function is constructed, which is used as a digital sequence thus allowing us to perform a Fourier transform. Another fruitful technical improvement is the closing of the sequence in the ring with further scanning of...

This paper addresses a bias problem in the estimate of wavelet power spectra for atmospheric and oceanic datasets. For a time series comprised of sine waves with the same amplitude at different frequencies the conventionally adopted wavelet method does not produce a spectrum with identical peaks, in contrast to a Fourier analysis. The wavelet power spectrum in this definition, that is, the tran...

A novel definition of a spread-spectrum signal as a signal whose Fourier bandwidth is much greater than its Shannon bandwith (one-half the number of dimensions of signal space required per second) is proposed. Six different communication systems are analyzed in terms of this definition. It is shown that there is a fundamental difference between the bandwidth expansion due to coding and that due...

The pseudo-spectral method is proposed for following the evolution of density and velocity uctuations at the weakly non-linear stage in the expanding universe with a good accuracy. In this method, the evolution of density and velocity uctuations is integrated in the Fourier Space with using FFT. This method is very useful to investigate accurately the non-linear dynamics in the weakly non-linea...

A simplified overview of time-domain jitter measurements is presented in this paper. The relationship between the timedomain jitter measurements and the power spectrum of the phase jitter is described using fundamental Fourier properties and basic random variables analysis. This leads to a unifying analysis and the results are in agreement with commonly accepted understanding of jitter accumula...

This work deals with computer analysis of tex­ tured surfaces. Descriptions of textures are form­ alized from natural language descriptions. Local texture descriptions are obtained from the direction­ al and non-directional components of the Fourier transform power spectrum. Analytic expressions are de­ rived for orientation, contrast, size, spacing, and in periodic cases, the locations of text...