spectral density
51Green's function (many-body theory) — In many body theory, the term Green s function (or Green function) is sometimes used interchangeably with correlation function, but refers specifically to correlators of field operators or creation and annihilation operators.The name comes from… …
52Noise temperature — In electronics, noise temperature is one way of expressing the level of available noise power introduced by a component or source. The power spectral density of the noise is expressed in terms of the temperature (in kelvins) that would produce… …
53Wiener–Khinchin theorem — The Wiener–Khinchin theorem (also known as the Wiener–Khintchine theorem and sometimes as the Wiener–Khinchin–Einstein theorem or the Khinchin–Kolmogorov theorem) states that the power spectral density of a wide sense stationary random process is …
54Coherence (signal processing) — Contents 1 Background 2 Definition and Formulation 3 Example 4 Extension to non stationary signals 5 …
55List of mathematics articles (S) — NOTOC S S duality S matrix S plane S transform S unit S.O.S. Mathematics SA subgroup Saccheri quadrilateral Sacks spiral Sacred geometry Saddle node bifurcation Saddle point Saddle surface Sadleirian Professor of Pure Mathematics Safe prime Safe… …
56Noise (electronics) — Electronic noise [1] is a random fluctuation in an electrical signal, a characteristic of all electronic circuits. Noise generated by electronic devices varies greatly, as it can be produced by several different effects. Thermal noise is… …
57Absorption spectroscopy — An overview of electromagnetic radiation absorption. This example discusses the general principle using visible light as a specific example. A white beam source – emitting light of multiple wavelengths – is focused on a sample (the complementary… …
58Periodogram — The periodogram is an estimate of the spectral density of a signal. The term was coined by Arthur Schuster in 1898Schuster, A., On the investigation of hidden periodicities with application to a supposed 26 day period of meteorological phenomena …
59Johnson–Nyquist noise — (thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation of the charge carriers (usually the electrons) inside an electrical conductor at equilibrium, which happens regardless of any applied… …
60Time series — Time series: random data plus trend, with best fit line and different smoothings In statistics, signal processing, econometrics and mathematical finance, a time series is a sequence of data points, measured typically at successive times spaced at …
