A lot of work has been done lately towards Open-Sourcing the LoRa PHY protocol. In terms of radio modulation LoRa uses a proprietary technique patented by Semtech based upon a form of Spread Spectrum (SS) actually called Chirp Spread Spectrum (CSS).
Investigating the signal with a SDR dongle while using Audacity to analyze the waveform we can deliver quite a few protocol components. Read more on the work has been done in the following article: “Decoding LoRa”
Though, using the more capable Ettus B210 along with Python and GNU Radio you can actually provide a more thorough analysis of the LoRa signal. Read the paper of Matt Knight and follow the Open-Source project to carry on development on GitHub: “GNU Radio OOT module implementing the LoRa PHY“
Video of Matt’s Presentation at GNU Radio Conference 2016: