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FreeDV


#1

FreeDV is a new digital voice system for HF communications. It is discussed in this month’s Practical Wireless magazine. It does look quite impressive. I wonder who will make the first FreeDV SOTA contacts?

https://freedv.org/

Demo at low signal strength:

http://www.rowetel.com/?p=6103


#2

Each to their own but I prefer the ssb analogue noise than the modulated digital noise.
Impressive they can get digital voice over that path and I can see the use cases and advantages it can bring. Might have a dabble in it but I prefered the sound analogue ssb makes.
73
Anthony


#3

It is hardly new. FreeDV has been around since 2015 and the RSGB have been running GB2RS News broadcasts on FreeDV for a couple of years. I tried it for a couple of weeks last year, but soon became bored with it. I concluded that it offered no advantage over standard SSB on the HF and LF bands.

73,
Walt (G3NYY)


#4

Thanks for the links, Richard. I was vaguely aware of FreeDV, but haven’t investigated further.

Reduced bandwidth, better overall SNR performance. Can sound a bit funny at first. Reminiscent of “Donald Duck” mode which was so disparaged in the early days. Whatever happened to that - I guess it never caught on? :wink:

Open source is good too :+1:


#5

It’s actually older than that Walt. As I used it twice to transmit the Wireless Institute of Australia (WIA)'s weekly broadcast when I still lived in Australia and I left Australia in February 2014. I’m sure the actual date is shown at freedv.org but my guess is that the first alpha versions came out at the start of 2013.

The latest version with 700D mode (700bits/sec 1.25kHz wide signal) is a major advance over the earlier versions.
Think of this on busy bands - 2 stations in the space of one SSB station and then with the advantage of a narrower bandwidth and hence better signal to noise ratio. Audio quality is still not brilliant but if you’re used to digital voice on VHF/UHF then it isn’t a lot worse than that. A good quality semi-pro microphone helps A LOT on freeDV as does setting the audio processing settings.

I believe it has already been used from a SOTA summit in Australia.

The Chinese RS-918 HF transciever and the Flex 6000 range both come with FreeDV as one of their voice modes and there is also an SM1000 speaker microphone from the inventor of CODEC2 that FreeDV uses if you want to avoid having to have a PC connected to the rig to run FreeDV. At the moment however none of these three options support the latest 700D mode - for that you need a PC beit Windows, MAC, Linux or Raspberry Pi.

73 Ed.


#6

I had my first freeDV in spring '17 on dm/ns-121. Coincidentally, my qso partner has the same trx as me, a mcHF from M0NKA. Unfortunately, the QRG had a lot QRN.
Here is the video: https://youtu.be/x-J1kLszeQQ

After that I had a few QSOs with Wolf, DK1HW.

73 Chris