SNR stands for Signal-to-Noise ratio and is sometimes abbreviated as S/N.
Signal-to-Noise ratio pertains to analog and digital communications in which signal strength is measured relative to background noise. The ratio is then measured in decibels.
Using a mathematical formula, S/N is found with the formula S/N = 20 log10(Vs/Vn) The Vs stands for incoming signal strength in microvolts and the Vn stands for noise level in microvolts. As a rule of thumb, if Vs = Vn, then S/N = 0.