Signal-to-noise ratio

Signal-to-noise ratio (often abbreviated SNR or S/N) is a measure used in science and engineering to quantify how much a signal has been corrupted by noise. It is defined as the ratio of signal power to the noise power, often expressed in decibels. A ratio higher than 1:1 (greater than 0 dB) indicates more signal than noise.

Definition

The signal-to-noise ratio, the ratio of the power of a signal (meaningful information) and the power of background noise (unwanted signal), is defined as:

SNR = P_signal / P_noise

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.

Decibels

The signal-to-noise ratio is often expressed in decibels, defined as:

SNR_dB = 10 log10 (P_signal / P_noise)

where log10 is the base-10 logarithm. The decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity.

Applications

Signal-to-noise ratio is used in various fields, including:

• Telecommunications: In telecommunications, SNR is often used to compare the level of a desired signal to the level of background noise.
• Data storage: In digital data storage, SNR measures the quality of a data readout.
• Imaging: In imaging, SNR refers to physical and perceived phenomena that affect image quality.
• Audio engineering: In audio engineering, SNR measures the clarity of an audio signal.

See also

• Noise (electronics)
• Noise figure
• Carrier-to-noise ratio
• Eb/N0
• Image noise
• Data compression ratio

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