Amateur radio
I have amateur radio licence (OK1MPE) from 1996 (?) when I did successfully a test on The Czech Telecommunication Office together with my friend Martin (OK1JLO).
Logically also in this "field" of interest (I mean general radio spectrum, not only HAM frequencies) I've made several designes with microcontrollers. It was a mix - roger beep, selective call, CTCSS generator, CW generators, controllers for repeaters (OK0BNC, OK0BG) and more. Some of them were published, some not:)
At this moment my HAM activity is on the background. I hope that in the future I will have more times for that.