| Amtor HF Teletype: Complete information, history, software and technical data. |
| Ham Radio and More Digital Topics Radio Show: RealAudio archives of talk radio covering a variety of ham radio mode topics. |
| Hoka Electronics: Information about a specialist range of standalone, DOS and Windows HF and VHF radio digital signals analysis and decoding equipment. |
| NB6Z - Digital HF Ham Radio: Information on modern modes of HF digital ham radio. HF band propagation. Related information and links. Ham radio Bulletin Board. |
| Official PSK31 Site: A new digital mode useful for keyboard to keyboard QSOs. Works at 31.25 bauds. Easy to use and monitor. Gives very good copy under poor SNR and is thus suitable for QRP. Uses BPSK or QPSK. |
| Packet Radio Resource Page: Provides a source for information and links to other sites related to various Digital Modes for Amateur Radio. |
| RTTY Fan Club: Everything about HF digital modes. Operating, contesting, software, hardware, DX information and bulletins, clubs, societies, and links. |
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