Luke Berndt posted on the HackRF-dev forum: “I built a Scanner app so I could use my HackRF to listen to my local fire department. It should work for any Moto SmartNet trunking systems that uses P25 CAI for the voice channels. It is based off the gr-smartnet code and uses DSD to decode the digital audio. I coded it in C++ and it use ncurses for the GUI.
It is still a bit rough, but if you have the right system in range, give it a try and let me know if it works!
Right now it was written to work with the HackRF, but you could probably do the same thing with 2 RTLSDRs.”