The signal-to-noise ratio (SNR) compares the level of the Wi-FI signal to the level of background noise. Sources of noise can include microwave ovens, cordless phones, Bluetooth devices, wireless video cameras, wireless game controllers, fluorescent lights, and more. Note that “noise” does not include co-channel interference from other radio transmitters — that is shown in the signal-to-interference ratio.
A ratio of 10-15dB is the accepted minimum to establish an unreliable connection; 16-24dB (decibels) is usually considered poor; 25-40dB is good and a ratio of 41dB or higher is considered excellent. If you hover over the measurement markers on the map and look at the AP names on the left, you can see the exact ratios for each location.
There are several ways you can adjust this heatmap view:
- Wi-Fi Network: Each Wi-Fi network detected can be mapped individually. Simply check the box next to the network(s) you wish to view on the left-hand side of the NetSpot window.
- Wi-Fi Channel: By clicking on the Project Configuration gear icon (on the bottom-left), you can also view the signal-to-noise ratio by channel.
- View: By clicking on the Project Configuration gear icon and selecting Toggle, you can choose whether to show your path, sampling points, and AP titles on the map.
- AP Detection Proximity: By clicking the Visualization Configuration gear icon (next to the visualization drop-down menu), you can filter out weaker access points (APs) by adjusting the AP detection proximity slider. The default is -60dBm.
- Min/Max Signal Level: By clicking the Visualization Configuration icon, the colors assigned to the SNR range can be adjusted by changing the Min Signal Level and Max Signal Level sliders. The default range is set to 0dBm (minimum) and -86dBm (maximum). You may get more helpful results if you set the minimum and maximum levels to a smaller range based your target ratio.