An anonymous reader writes: Software Defined Radio must be hard to create, right? Tools like GNU Radio and GNU Radio Companion make it much easier to build radios that can tune AM, FM, and even many digital modes. Of course, you need some kind of radio hardware, right? Not exactly. Hackaday has one of their video hands on tutorials about how to use GNU Radio with no extra hardware (or, optionally, a sound card that you probably already have). The catch? Well, you can't do real radio that way, but you can learn the basics and do audio DSP. The next installment promises to use some real SDR hardware and build an actual radio. But if you ever wanted to see if it was worth buying SDR hardware, this is a good way to see how you like working with GNU Radio before you spend any money.