The airspy device is a low cost high performance SDR with better performance compared with the well known rtl-sdr.
For more information about the airspy please visit http://airspy.com/.
If you start welle.io without any options welle.io will detect the airspy device automatically. After enabling the “Expert mode” you can check if welle.io detects the device successfully.
You can also use the command line option “-d” to force welle.io to use the airspy device.