SNR

Signal to Noise Ratio.

The SNR (Signal-To-Noise Ratio) of a system or component is defined as the ratio of signal level to the noise level. SNR is expressed in decibels. It is calculated by dividing the signal power by the noise power. A ratio bigger than 1 dB indicates that the signal is more than the noise. Conversely, if the ratio is less than 1, it indicates that the noise level is bigger than the signal level.

If the power of the signal is less than the power of the noise, i.e. the SNR < 1, the signal becomes unusable.

When an audio component for example has a SNR of 100 dB, it means that the level of the audio signal is 100 dB higher than the level of the noise. This means that a SNR of 100 dB is better than one that is for example 70 dB.