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Old May 31st 18, 06:21 PM posted to,
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Default [KB6NU] Will digital voice (on HF) ever be a thing?

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Will digital voice (on HF) ever be a thing?

Posted: 30 May 2018 01:02 PM PDT

A couple of days ago, Bruce, K6BP, tweeted:

FreeDV radio digital voice 1.3 released as source, no packages yet. 700D
mode reported to consistently outperform SSB, is loud and clear while SSB
is inaudible, error-free transatlantic communication reported.

For those not familiar with FreeDV, heres what the website has to say:

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.* There are several reports of
the new FreeDV 700D mode outperforming SSB at low SNRs.** At high SNRs
FreeDV 1600 sounds like FM, with no annoying analog HF radio noise.

Alternatively you can buy a SM1000 FreeDV adaptor that allows you to run
FreeDV (1600 mode) on any HF radio without a PC or sound card.* If you are
a hardware or software developer, you can integrate FreeDV into your
project using the LGPL licensed FreeDV API.

Speech is compressed down to 700-1600 bit/s then modulated onto a 1.25 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 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.

That all sounds good, but FreeDV has been criticized as sounding too
robotic. I forwarded the tweet to my friend Rick, KA8BMA, who designed the
hardware for the SM1000 FreeDV adaptor. He said, There are several male and
female samples for the new 700D mode. Check it out at

I listed to the sample QSO I found there, and I must admit that it did
sound better than when I had investigated FreeDV a couple of years ago.
Maybe these new improvements will make this a more enjoyable mode to
operate. It certainly does have some distinct advantages over plain old
single sideband. That being the case, perhaps FreeDV will actually become a
thing sooner rather than later.

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KB6NUs Ham Radio Blog.

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