I came across a YouTube video from RJ of Lynx Electronics Lab talking about FreeDV, an experimental digital voice mode available for use on the HF bands without having to resort to an internet link...in other words, the magic happens entirely with software hosted on your shack computer and entirely over the airwaves. Real radio, not internet!
From the FreeDV website:
FreeDV is a suite of digital voice modes for HF radio. Our flagship mode is the Radio Autoencoder (RADE). You can run RADE using a free GUI application for Windows, Linux and macOS that allows any SSB radio to be used for high quality digital voice.
FreeDV technology is being developed by an international team of radio amateurs working together on Machine Learning, DSP, coding, design, user interface and testing. The project is managed by a 6 person Project Leadership Team (PLT). Current development is being generously funded by an ADRC grant and our Financial Sponsor is the Software Freedom Conservancy. All software is open source, released under the (a) GNU Lesser Public License version 2.1 (GUI and legacy FreeDV modes) and two-clause BSD license (RADE).
Why FreeDV?
Amateur Radio is transitioning from analog to digital, much as it transitioned from AM to SSB in the 1950s and 1960s. 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 unique as it uses 100% Open Source Software, including the speech 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 manufacturer’s closed technology.
Controlled testing suggests our flagship RADE technology compares favorably to SSB on high and low SNR channels.
The on air demonstration was remarkable, and effectively demonstrated the difference between a typical SSB QSO and a contact made using the FreeDV mode. It was really impressive. The point was made in the video that the major radio manufav=cturers are apparently looking into incorporating this technology into new radio production. I hope this is true, but I guess we'll see in the long run.
I downloaded the free software from the FreeDV website at freedvorg and successfuly set up a PTT configuration using Hamlib. I'm still playing around with the audio IO.
Apparently, this mode has been around for a while, but I certainly had no clue. Thanks RJ (I never did get your call) for pointing me in the right direction.