freedv - 1.3.1-3 main

FreeDV is a digital voice mode intended for transmission and
reception over high-frequency (HF) radio. It uses a frequency
division multiplex (FDM) modem with 15 carriers and no forward error
correction (FEC). A low bit-rate voice coder-decoder (Codec 2)
provides voice quality without the listener fatigue caused by noise
and interference normally associated with analog single sideband
(SSB) voice. A HF SSB transceiver, personal computer and two sound
cards are required. Path simulation and on-the-air HF testing have
shown that decoding voice is possible at a signal-to-noise ratio of
4 dB.
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The FreeDV software was developed by David Rowe (Codec 2, FDM
modem implementation, integration) and David Witten (GUI,
architecture design). The FreeDV design and user interface was based
on the earlier FDMDV program which was developed by Francesco
Lanza. The FDM modem design and development was supported from Peter
Martinez.