Software Defined Radio with HackRF, Lesson 1 - Great Scott Gadgets

Great Scott Gadgets

Software Defined Radio with HackRF, Lesson 1


In order to clearly see my screen during the demonstration, viewing the video in full screen mode may help. Even better: You can download this video in high resolution (720p). (torrent)

In this Lesson

  • welcome to the video series
  • introduction to SDR
  • introduction to HackRF
  • course background
  • introduction to GNU Radio Companion
  • “hello world”, receiving FM radio


  1. FM radio flowgraph: Create a flowgraph in GNU Radio Companion like the one in the video or the screenshot below. Test the flowgraph by listening to a strong FM radio signal.

FM radio RX flowgraph screenshot

  1. Add a channel slider: Add a slider to your FM radio flowgraph and use it to change channels while your flowgraph is running.

  2. Add a second channel: Update your FM radio flowgraph so that it allows you to listen to two radio stations at the same time. Hint: Use an Add block to combine two audio signals.



  • 25 August 2014: The original video encoding had some problems. I produced a new encoding so that iPad and Safari users can hear the sound. I also improved the audio/video synchronization and filtered the audio a bit.

  • 25 August 2014: I pointed out the “gears” icon in GNU Radio Companion. In future versions, this changes to a triangular “play” icon.

  • 21 July 2022: This series of videos was produced using an older version of GNU Radio. Most of the content still applies to the newer versions, but there are some key differences that were introduced in GNU Radio v3.8 onwards:

    • The user interface has switched from WX GUI to QT GUI

    • The new GUI Sink blocks have an optional control panel that is disabled by default. This can be enabled in the block properties under Config.

    • Some blocks used in this lesson have changed name when switching from WX to QT:

      • WX GUI FFT Sink changes to QT GUI Frequency Sink
      • WX GUI Slider changes to QT GUI Range

Software Defined Radio with HackRF is copyright 2014, 2015 by Michael Ossmann and is released under the CC BY license.