Signal-to-noise ratio (often abbreviated SNR or S/N) is a
measure used in science and engineering that compares the level
of a desired signal to the level of background noise. It is
defined as the ratio of signal power to the noise power. A ratio
higher than 1:1 indicates more signal than noise. While SNR is
commonly quoted for electrical signals, it can be applied to any
form of signal (such as isotope levels in an ice core or
biochemical signaling between cells). Signal-to-noise ratio is
sometimes used informally to refer to the ratio of useful
information to false or irrelevant data in a conversation or
exchange. For example, in online discussion forums and other
online communities, off-topic posts and spam are regarded as
"noise" that interferes with the "signal" of appropriate
discussion. where P is average power. Both signal and noise
power must be measured at the same or equivalent points in a
system, and within the same system bandwidth. If the signal and
the noise are measured across the same impedan