Software Defined Radio

qspectrumanalyzer

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. Official-repo package.

Using it

  1. Pick a backend in settings — rtl_power for RTL dongles, or a Soapy backend for other hardware.
  2. Set the start and stop frequency of the range you want to survey, plus the bin size (resolution).
  3. 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.
  4. 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.