Equivalent noise resistance

In telecommunication, an equivalent noise resistance is a quantitative representation in resistance units of the spectral density of a noise-voltage generator, given by ${\displaystyle R_{n}={\frac {\pi W_{n}}{kT_{0}}}}$ where ${\displaystyle W_{n}}$ is the spectral density, ${\displaystyle k}$ is the Boltzmann's constant, ${\displaystyle T_{0}}$ is the standard noise temperature (290 K), so ${\displaystyle kT_{0}=4.00\times 10^{-21}\,[Ws]}$.

Note: The equivalent noise resistance in terms of the mean-square noise-generator voltage, e², within a frequency increment, Δ f, is given by

${\displaystyle R_{n}={\frac {e^{2}}{4kT_{0}\,\Delta f}}.}$

 This article incorporates public domain material from the General Services Administration document: "Federal Standard 1037C".