GNU Radio for Exploring Signals
Talk Hard: A technical, historical, political, and cultural look at FM
In GNU Radio, we often find ourselves going to the FM broadcast stations as a first introduction to radio, software radio, and signal processing. FM broadcast is nearly ubiquitous and has a narrow enough bandwidth that very inexpensive hardware all over the world can work with it. It also has an interesting enough structure that allows us to go from simple to more complicated GNU Radio applications for studying all sorts of ways in which we can process it as a signal.
FM broadcasting is present almost anywhere in the world, and its structure makes it an interesting challenge and good learning exercise for developing GNU Radio applications. Likewise, almost any software radio RF front end is capable of processing FM: from the very cheap RTL-SDR dongles to the more expensive USRPs. In this talk, I will introduce FM from its historical roots and walk through why it is a technologically important development as I build more complicated GNU Radio applications to explore the FM waveform. As a broadcast medium, FM has also played an important political, social, and cultural role in the last century. Aside from the technical development of how to process FM signals, I will use this lecture as an introduction to regulatory agencies and band planning. Part of this will involve the development, problems, and importance of FM pirate radio. The lecture will involve a demonstration of embedded GNU Radio applications that will showcase the FM capture effect by imitating a (very) low power radio station.