Software Defined Radio

gqrx

gqrx is the receiver most people reach for first, because it makes SDR visible. It gives you a live spectrum plot and a scrolling waterfall, a tuner you click to move around the band, and demodulators for the common analog modes (AM, FM, SSB, CW). You watch the waterfall, spot a signal as a bright streak, click it, and listen. For exploring a band, finding what’s transmitting, and getting a feel for the spectrum, nothing beats it.

gqrx is a graphical application, so Oniomarchy launches it into its own window from Security → Software Defined Radio → gqrx. Official-repo package.

Using it

1. Configure the device on first launch — gqrx lists the SDRs SoapySDR found; pick yours and set a sample rate.
2. Tune by clicking on the frequency display or dragging across the spectrum.
3. Pick a demodulator (WFM for broadcast FM, AM for airband, SSB for ham) and adjust the filter width to match the signal.
4. Watch the waterfall to spot activity — bursts, carriers, and digital signals all have recognizable shapes.

gqrx is the exploration front end; once you’ve found and characterized a signal, tools like inspectrum and urh are where you dig into decoding it.