Back in college, I had to take a course in signal processing. I did miserably at it, for a variety of reasons — I didn’t have the right math background, I was busy with the student newspaper, and I had no idea what was going on. But it was clear to me, even with my slim grasp of the subject, that manipulation of radio signals could be potentially quite interesting and useful. Fast forward two and a half decades, and wireless systems are all over the place, from WiFi to cellular networks. And the GNU project, unknown to many, has a system known as GNU Radio, that lets you control them. In this talk, Tim O’Shea introduces GNU Radio, telling us what it can do, and why you would even want it.