spectral density function
preferred label: تابع چگالی طیفی @fa
type: Concept
related: quadrature spectrum

quadrature spectrum
related: spectral density function
broader: spectral analysis
preferred label: طیف درجه دوم @fa
type: Concept

spectral analysis
preferred label: آنالیز طیفی @fa
type: Concept
narrower: quadrature spectrum