ATAK Plugin that grab RSSI values from local Access Points and try to plot where they are on the map.
The operations are simple, press Start to begin scanning for WIFI Access Points (AP) the longer and the more you move around the area of interest the better. When ready, press Stop and then Compute. This will take all the AP measurement readings and try to triangluate where the AP is.
Note: You will likely want to disable WIFI scan throttling in the Android Developer settings menu otherwise your scans will not be as frequent as possible.