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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 ovens.
Double-clicking on the SNR legend on the status bar allows you to configure the color scheme and change its value range.
Suggested Solutions
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 suggested:
| § | 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 typically lower. |
| § | 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 level.
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