Gqrx

Gqrx is an open‑source software‑defined radio receiver built on GNU Radio and the Qt graphical toolkit. It detects SDR hardware connected to the computer, processes the incoming I/Q data, and lets users adjust frequency, gain and apply corrections such as frequency offset and I/Q imbalance. The program supports a range of devices, including Airspy, Funcube Dongles, rtl‑sdr, HackRF and USRP models.

The interface provides demodulation for AM, SSB, CW, FM‑N, FM‑W (mono and stereo) and a special FM mode for NOAA APT images, together with a variable band‑pass filter, AGC, squelch and noise‑blanking. Users can view spectra and water‑falls, record or playback audio and raw baseband data as WAV files, and operate in a spectrum‑analyzer mode where processing is disabled. Basic remote control is available via TCP, and audio can be streamed over UDP.

Gqrx is distributed under the GNU General Public License, allowing anyone to modify or extend the software. It is released as source code and binary packages for multiple platforms, including macOS, and is considered stable for regular use.