FreeDV is an application for Windows and Linux that allows any HF SSB radio to be used for digital voice mode with a bandwidth of just 1.1 kHz
Speech is compressed down to 1400 bit/s then modulated onto a 1100 Hz wide QPSK signal which is sent to the Mic input of a SSB radio.
On receive, the signal is received by the SSB radio, then demodulated and decoded by FreeDV.
- Codec 2 voice coder and FDMDV modem
- 50 baud 14 QPSK voice data
- 1 Centre BPSK carrier with 2x power for fast and robust synchronisation.
- 1.125 kHz spectrum bandwidth (half SSB) with 75 Hz carrier spacing
- 1400 bit/s data rate with 1375 bit/s open source Codec 2 voice coding and 25 bit/s text for call sign ID
- No interleaving in time or FEC philosophy resulting in low latency, fast synchronization and quick recovery from fades.
- 44.1 or 48kHz sample rate sound card compatible
Watch FreeDV, the new HF digital audio program for Radio Amateurs.
Digital Voice Google Group - https://groups.google.com/forum/?fromgroups#!forum/digitalvoice
FreeDV - http://freedv.org/