Second-order spectrum extraction based on ionospheric clutter

Spectrum Sensing Algorithms Based on Second-Order Statistics

Cognitive radio is a new concept of reusing spectrum in an opportunistic manner. Cognitive radio is motivated by recent measurements of spectrum utilization, showing unused resources in frequency, time and space. Introducing cognitive radios in a primary network inevitably creates increased interference to the primary users. Secondary users must sense the spectrum and detect primary users’ sign...

Motion Blurring Direction Identification Based on Second-Order Difference Spectrum

An identification method for uniform linear motion blurring direction based on second-order difference spectrum was proposed. The power spectrum of the blurred image was calculated after the Laplace second-order difference, and then the power spectrum was processed by the homomorphic filtering and the circular low-pass filtering. The blurring direction was attained by linear fitting of the freq...

On the Generalized Spectrum for Second-order Elliptic Systems

We consider the system of homogeneous Dirichlet boundary value problems (*) Liu = A[an(x)u + a\2(x)v], L2V = ti[ai2{x)u + a.22{x)v] in a smooth bounded domain fi C R", where Li and £2 are formally selfadjoint second-order strongly uniformly elliptic operators. Using linear perturbation theory, continuation methods, and the Courant-Hilbert variational eigenvalue characterization, we give a detai...

The second order spectrum and optimal convergence

Second Order General Slow-roll Power Spectrum

Recent combined results from theWilkinson Microwave Anisotropy Probe (WMAP) and Sloan Digital Sky Survey (SDSS) provide a remarkable set of data which requires more accurate and general investigation. Here we derive formulae for the power spectrum P(k) of the density perturbations produced during inflation in the general slowroll approximation with second order corrections. Also, using the resu...