20 lines
979 B
Plaintext
20 lines
979 B
Plaintext
FreeDV is a Digital Voice mode for HF radio.
|
|
|
|
You can run FreeDV using a free GUI application for Windows, Linux and
|
|
OSX that allows any SSB radio to be used for low bit rate digital
|
|
voice. Alternatively you can buy a SM1000 FreeDV adaptor that allows you
|
|
to run FreeDV on any HF radio without a PC or sound card.
|
|
|
|
Speech is compressed down to 700-1600 bit/s then modulated onto a
|
|
.25 kHz wide signal comprised of 16 QPSK carriers which is sent to the
|
|
Mic input of a SSB radio. The signal is received by an SSB radio, then
|
|
demodulated and decoded by FreeDV. FreeDV 700C is approaching SSB in
|
|
its low SNR performance. At high SNRs FreeDV 1600 sounds like FM,
|
|
with no annoying analog HF radio noise.
|
|
|
|
FreeDV was built by an international team of Radio Amateurs working
|
|
together on coding, design, user interface and testing.
|
|
FreeDV is open source software, released under the GNU Public License
|
|
version 2.1. The modems and Codec 2 speech codec used in FreeDV are
|
|
also open source.
|