The noise floor in radio communications is the baseline level of unwanted background electromagnetic energy present in a system. It sets the minimum threshold a signal must exceed to be heard or decoded. Any transmission weaker than the noise floor will be lost in the static.

The noise floor is a combination of natural and human-made interference. Cosmic radiation and atmospheric static also contribute.

The performance of a radio receiver is usually determined by its Signal-to-Noise Ratio (SNR). If your signal is just barely creeping above the noise floor, you will likely experience static, dropped data packets, or fuzzy audio.