Remember the Air Traffic Control post from earlier? Yeah, well, it turns out you can use the same cheap dongle to pick up APCO-25 transmissions.
APCO-25 is the protocol that most public safety radios use. Scanners that are cable of intercepting these transmissions have been around for over ten years, but they still cost over $400. Even used they’re not very cheap.
I think this will be my lunchtime project.