The signal-to-noise ratio (SNR) is a measure to compare the level of the desired Thread radio signal strength to the level of background noise or signal strength of other interfering signals in the same frequency band.

The SNR is calculated by dividing the signal strength (S) by noise signal strength (N).


You can also subtract logarithms to calculate the SNR. The difference between the numbers equals the SNR.
An example for a radio signal with a strength of -10 dB and a noise signal of -50 dB would be:
-10 minus -50 dB equals 40 dB.

SNR must be higher than 10 dB to achieve stable communication; higher than 20 is ideal. See figure below.

Signal-to-noise-ratio (SNR)