This instrucatables show how to make an ESP8266 version WiFi Analyzer clone.
WiFi Analyzer is a handy app in Android, it help to visualize the WiFi signal information around you. It is very useful for helping select a right channel for setting a new AP. If you selected a channel that as same as another AP near you, you may encounter interference and degrade the network performance.
ESP8266 WiFi Analyzer – [Link]