Welch FFT Segment Size Selection Method for FFT Based Wide Band Spectrum Measurement

Welch FFT Segment Size Selection Method for Spectrum Awareness System

We create a practical method to set the segment size of the Welch FFT for wideband and long-term spectrum usage measurements in the context of hierarchical dynamic spectrum access (DSA). An energy detector (ED) based on the Welch FFT can be used to detect the presence or absence of primary user (PU) signal and to estimate the duty cycle (DC). In signal detection with the Welch FFT, segment size...

An FFT - based Method for Attenuation

A problem in three-dimensional imaging by a confocal scanning laser microscope (CSLM) in the (epi))uorescence mode is the darkening of the deeper layers due to absorption and scattering of both the excitation and the uorescence light. In this paper we propose a new method to correct for these eeects. Our approach, valid for weak attenuation, consists in multiplying the measured uorescent intens...

About FFT Spectrum Analyzers

For one thing, some measurements which are very hard in the time domain are very easy in the frequency domain. Consider the measurement of harmonic distortion. It's hard to quantify the distortion of a sine wave by looking at the signal on an oscilloscope. When the same signal is displayed on a spectrum analyzer, the harmonic frequencies and amplitudes are displayed with amazing clarity. Anothe...

Newton's method and FFT trading

Let C[[z]] be the ring of power series over an effective ring C. In Brent and Kung (1978), it was first shown that differential equations over C[[z]] may be solved in an asymptotically efficient way using Newton’s method. More precisely, if M(n) denotes the complexity for multiplying two polynomials of degree < n over C, then the first n coefficients of the solution can be computed in time O(M(...

FFT Based Option Pricing