Useful webiste
- Utility DXers Forum
- Utility DXers Forum Home Page
- IK1YDE - Segnali e Modulazioni Digitali
- Monitoring Utility Stations - Digital Mode
- Ary Boender, Numbers & Oddities
- The Italian HF Archive
- Ed Deasy, Analysis RTTY signals
- VLF.IT
- Utility Monitoring Central
- International Telecommunication Union (ITU)
- HF ASIA
- Digital Mode Samples