This app uses the nRF Connect for Desktop UI framework. Shared UI elements such as Select device, About tab, and Log panel are described in the Common user interface documentation.
The available options and information change after you select a device. When you connect a supported device and select it in the Select device menu, the RSSI Viewer app programs the device with the correct sniffer firmware, and then connects to one of the available serial ports. Sniffing starts automatically.