- Broadcast radio — long, medium and shortwave stations from around the world
- Amateur (ham) signals — voice, CW and digital conversations across the bands
- Ship-to-shore communications — maritime voice and data
- Aircraft ADS-B — decode and map aircraft positions overhead
- FT8 & FT4 decoding — the hugely popular weak-signal digital modes
- Other digital modes — a whole world of data signals to decode
- Weather data — facts and imagery from weather services and satellites
- Amateur satellites — listen to signals from orbiting amateur payloads
- Television — experiment with broadcast signal reception
- Slow Scan TV (SSTV) — decode pictures sent over the air
- CW & Morse code — the timeless art of the dits and dahs
Each of these is a rabbit hole in its own right. Many listeners start with broadcast and amateur signals, then discover the addictive fun of decoding — watching aircraft appear on a map, or FT8 contacts roll in from across an ocean on a tiny signal you can barely hear.