This visualization shows the signal-to-noise ratio (SNR) measured
in dB. SNR is a measure to quantify by how much the signal level
exceeds the noise level. Noise is generated by non-802.11 sources
of radio waves (this includes 802.11 frames damaged during
propagation). In low SNR zones, client devices may not be able to
communicate with APs. SNR is shown for the AP that has the
strongest signal in the given map area among the APs selected for
analysis. You can deselect one or several of the selected APs to
see SNR values for less strong APs.
In a typical environment, the noise level is about -90 dBm. The
signal level measured within a few meters from the AP would be
about -50 dBm. This gives an SNR value of 40 dB, which is
considered excellent. Marginal connectivity is possible when the AP
signal level is -85 dBm, so an SNR value of 5 dB is considered
poor. A higher noise level and, correspondingly, a lower SNR are
usually caused by Bluetooth devices, cordless phones, and microwave
Double-clicking on the SNR legend on the status bar allows you to
configure the color scheme and change its value range.
When low SNR areas are discovered, two possible strategies should
be considered: increasing the signal level or decreasing the noise
level. The first strategy is discussed in the previous chapter; to
decrease the noise level, the following solutions are
Check the environment for potential sources of noise and turn them
off, if possible, to see how that affects SNR.
If you experience low SNR values in the 2.4 GHz band, consider
switching your APs to the 5 GHz band, where noise level is
If switching to the 5 GHz band is not an option, try to select a
different channel in the 2.4 GHz band.
Note that identifying and removing the source of noise might not be
an easy task. In practice, the easiest solution is usually
increasing the signal level rather than decreasing the noise