Noise power

In telecommunication, the term noise power has the following meanings:
 * 1) The measured total noise in a given bandwidth at the input or output of a device when the signal is not present; the integral of noise spectral density over the bandwidth
 * 2) The power generated by a random electromagnetic process.
 * 3) Interfering and unwanted power in an electrical device or system.
 * 4) In the acceptance testing of radio transmitters, the mean power supplied to the antenna transmission line by a radio transmitter when loaded with noise having a Gaussian amplitude-vs.-frequency distribution.

Noise power can be calculated by multiplying the noise spectral density with the signal bandwidth
 * $$N_\text{p} = k_\text{B}TB,$$

where
 * k$B$ = Boltzmann constant ≈
 * T = absolute temperature of the device
 * B = bandwidth