Thanks Walter and Mooneer. I'd be interested to know the RMS power you
can develop with 700D/E with the clipper option.
- David
On 20/12/20 10:30 am, Mooneer Salem wrote:
Looks like it's working reasonably well, though the 20 meter band fell
out shortly after we all got it installed. More testing tomorrow for
sure. :)
-Mooneer K6AQ
On Sat, Dec 19, 2020 at 2:26 PM <[email protected]
<mailto:[email protected]>> wrote:
Have it loaded and running now.
Working on a couple others as I type to get some end to end testing.
Many thanks David, and best of the holidays.
Walter/K5WH
-----Original Message-----
From: David Rowe <[email protected] <mailto:[email protected]>>
Sent: Saturday, December 19, 2020 3:34 PM
To: [email protected]
<mailto:[email protected]>
Subject: [Freetel-codec2] FreeDV 1.5 - 700E and OFDM compression
I've been working on a new FreeDV 700E mode, and some compression
for FreeDV 700D and 700E to increase the average power. A
Christmas present for you to play with
700E is designed to handle fast fading like 700C, but like 700D
has powerful FEC. My bench tests indicate 700C & E are equivalent
on moderate fading channels (2Hz dopdler/2ms spread), but on very
fast fading (4Hz/4ms) 700E does better - 700C & D fall over. 700D
works better at lower SNRs on slow fading channels.
I've also been testing against compressed SSB, which as Helmut
suggests is pretty hard to beat, as it's so robust to fading.
However 700E is hanging on quite well with fast fading, and
becomes noise free as the SNR increases.
-/-
The second innovation is compression of the 700C/D/E waveforms, to
increase average power significantly.
Please be careful adjusting the Tx drive and especially enabling
the Tool - Options - Clipping. It can drive your PA quite hard. I
have managed 40W RMS out of my 75W PEP transmitter. Make sure
your transmitter can handle long periods of high average power. My
IC7200 and
FT-817 seem OK.
At the same equivalent peak power - 700D is doing well when
compressed SSB is -5dB SNR and rather hard on the ears.
-/-
Peter VK3RV, Jose LU5DKI, and Barry VK3BRT tried 1.5.0 last night
and report it works on real HF channels.
The latest manual describes the new features:
https://github.com/drowe67/freedv-gui/blob/118cb66ee4679518185db871ec0ae68071c406a4/USER_MANUAL.md
You can download Windows 32 and 64 bit versions of FreeDV 1.5 here:
http://rowetel.com/downloads/freedv
-/-
I'd be interested in any feedback. If you have an interesting
test case (e.g. a bug or comparing SSB to FreeDV), pls send me off
air recordings of signals (FreeDV Tools-Record File from Radio).
That helps me make objective comparisons. Recordings are much
more useful to me than anecdotes or subjective reports.
Thanks,
David
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