If you can get your hands on a new-old-stock MX614 IC, it's semi-simple to play with in hardware. There are many software-based packages as well if you're more

If you can get your hands on a new-old-stock MX614 IC, it's semi-simple to play with in hardware. There are many software-based packages as well if you're more inclined to enjoy that style. mx614 circuit - https://www.cmlmicro.com/wp-content/uploads/2017/06/FAQs-MX604.pdf https://www.cmlmicro.com/wp-content/uploads/2017/06/FAQs-MX6... attiny style - https://sites.google.com/site/wayneholder/attiny-4-5-9-10-assembly-ide-and-programmer/bell-202-1200-baud-demodulator-in-an-attiny10 https://sites.google.com/site/wayneholder/attiny-4-5-9-10-as... direwolf softmodem - https://github.com/wb2osz/direwolf https://github.com/wb2osz/direwolf