Michael Ossmann, one of the developers of the amazing and affordable HackRF SDR transceiver, is releasing a tutorial series on using GNU Radio. “This ongoing video series will be a complete course in Software Defined Radio (SDR). In this course, you’ll build flexible SDR applications using GNU Radio through exercises that will help you learn the fundamentals of Digital Signal Processing (DSP) needed to master SDR. For the over-the-air exercises, you’ll need a HackRF One or other SDR peripheral.”
The tutorial series can be found on Michael’s GreatScottGadgets site.
(Note that the HackRF SDR featured in this series, while costing considerably more than a $20 RTL-SDR dongle, covers a greater frequency range and includes a low-power transmitter. Still, at around $300 it falls in the budget of more hackers than the $1000+ USRP Ettus series.)