FreeDV HF Digital Voice for Radio Amateurs

[KC9OIS]

Digital modes and technology seem to be making some headway in Amateur Radio. I seeing more software and hardware being developed these days. Here is another interesting program for digital voice on SSB.

Amateur Radio is transitioning from analog to digital, much as it transitioned from AM to SSB in the 1950's and 1960's. How would you feel if one or two companies owned the patents for SSB, then forced you to use their technology, made it illegal to experiment with or even understand the technology, and insisted you stay locked to it for the next 100 years? That's exactly what was happening with digital voice. But now, hams are in control of their technology again!

FreeDV is a GUI application for Windows, Linux and MacOS (BSD and Android in development) that allows any SSB radio to be used for low bit rate digital voice.

Speech is compressed down to 1600 bit/s then modulated onto a 1.25 kHz wide 16QPSK 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. Communications should be readable down to 2 dB S/N, and long-distance contacts are reported using 1-2 watts power.

FreeDV is unique as it uses 100% Open Source Software, including the audio codec. No secrets, nothing proprietary! FreeDV represents a path for 21st century Amateur Radio where Hams are free to experiment and innovate, rather than a future locked into a single manufacturers closed technology.

Here is what you need:

A SSB receiver or transceiver
FreeDV software, download links are below.
A Windows or Linux PC with one (receive only) or two sound cards.
Cables to connect your PC to your SSB radio.

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 FDMDV modem and Codec 2 Speech codec used in FreeDV are also open source.
Here's an interesting program

VideoAmateur Radio is transitioning from ana ... vAJBkOWKZ4

Link to website for more information and download :http://freedv.org/tiki-index.php

[kb9mwr]

I have been following Codec2 for a while.

I think its a good idea. But I really have my doubts as to when, (if ever) this will be something on a chip in a radio.

One day the HT of the future will support after market firmware updates like the WRT-54G does!

I am not one of those hell bent on not using DVSI codecs. They work and the chips can be bought fairly cheap in small quantities. If either wasn't the case, then I'd have issues with the whole thing. What's more, programs like DSD can decode the audio totally in software. To date, DVSI hasn't issued any legal threats to anyone using or coding the hobbyist program. While that program doesn't decode the earlier AMBE that D-Star uses, people are working on it. The reason it isn't supported yet is there are no TIA docs, combined with coding authors needing to be a bit anonymous.

I am not much into HF, but have thought about interfacing something like it to a small computer like the Pi in your car, interfaced to the 9600 packet port of your existing analog FM rig .

Here a guy wrote a GMSK modem that incorporates Codec2, that does just that for a FM rig.

http://villazeebries.krbonne.net/hamstuff/?p=307

[KC9OIS]

Codecs are a start and it's ideas like this that stimulate others to come up with something better (like open source firmware and being able to flash your radio). Now there's a concept! Amateur Radio based on Open Source code and modular kits, reasonably priced. QST mags that are 3/4 articles instead of ads. Maybe someday...

That's what's so great about a forum like this. There is so much new stuff out there, even if you spent 10 hours a day 7 days a week you couldn't keep up with it. Hopefully, as the word gets out, more people will post about new things they come across and share them with everyone.