By using Software Defined Radio (SDR), one could capture the broadcasted radio waves. However, usually this information is not useful in raw form. Captured waves need to be processed and decoded in order to obtain useful information from them.
This project is to intercept radio waves and use the digital signal processing methodology then apply appropriate demodulation/decode to peek into the data transmitted over the waves.
SDR with antenna were used in conjunction with open-source software to capture waves, signal process, decode, and playback the data. Known protocols were used to test the capabilities of SDR before moving onto decoding UAV, which encoding scheme is not very well known at the moment.
Project was partially successful. Honolulu City County’s trunked radio system was successfully decoded and was able to listen in onto the chatter. However, attempts to decode 802.11g standard was unsuccessful due to complexity of encoding/decoding process.
This progress could be used as foundation for decoding UAV communications and possibly transmitting commands to hijack the vehicle.
Following is a snippet from GNU Radio auto parsing feature: Sample Code
Bryant S. Lee 