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Wireless & Mobility · Foundational

Signal-to-Noise Ratio (SNR)

The difference in dB between received signal strength and the noise floor.

Definition

SNR is calculated as signal (dBm) minus noise (dBm) and expresses how far a signal rises above the background noise. Higher SNR allows more complex modulation and higher data rates. Common design minimums are 20 dB for data and 25 dB for voice.

Example

A -65 dBm signal over a -92 dBm noise floor gives 27 dB SNR.

Exam tip

SNR is in dB, not dBm, because it is a ratio of two powers.

Don't confuse it with

Related terms