qspectrumanalyzer turns your SDR into a spectrum analyzer. Rather than listening
to one signal, it sweeps across a wide frequency range and plots the power it finds
— live, as a spectrum and a waterfall — so you can see, at a glance, what parts of
a band are busy and when. It drives several backends (including
rtl_power and SoapySDR sources), so it
works with the hardware you already have. It’s the tool for the “what’s even
happening across this whole band?” question that comes before you zoom in on any
single signal.
qspectrumanalyzer is a graphical application, launched into its own window from
Security → Software Defined Radio → qspectrumanalyzer.
Using it
Pick a backend in settings — rtl_power for RTL dongles, or a Soapy
backend for other hardware.
Set the start and stop frequency of the range you want to survey, plus the
bin size (resolution).
Start the sweep — the display fills in with a live spectrum on top and a
waterfall building underneath, so intermittent transmissions show up as marks
in the history.
Read the survey to decide where to point a receiver like
gqrx for a closer look.
It’s a surveying instrument: wide and shallow, to find activity, not to decode it.