Noise power

In telecommunications, 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 supplied to the antennatransmission line by a radio transmitter when loaded with noise having a Gaussian amplitude-vs.-frequency distribution.

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

• k_B is the Boltzmann constant ≈ 1.38×10 J⋅K;
• T is the absolute temperature of the device; and
• B is the bandwidth.