SDR++ is a cross-platform and open source software-defined radio application with the aim of being bloat free and simple to use. It is comparable to the Windows program SDR# (SDRSharp).
Installation
Warning: As of writing SDR++ does not support RTAudio version 6 and above, compilation will fail if you have version 6 or above installed on your system. If you wish to compile the package anyway (without disabling RTAudio support altogether), check that nothing else is using rtaudio and downgrade to version 5.2.0-2.
SDR++ is available in the AUR from sdrpp-gitAUR. This will build the default modules in this list along with BladeRF, LimeSDR, SDRplay, PortAudio and M17 decoding support.