Hi Ross,
We've already moved through steps 1 (development against software
channel simulator) and step 2 (one-way real world HF Tx to SDRs), our
progress to date is summarised here:
http://www.rowetel.com/?p=7688
As you can see the physical layer aspect of the project is coming along
nicely. We have indeed been developing against CCIR poor (Multi-Path
Poor or MPP in Ionos/Winlink nomenclature), and are getting encouraging
results (see PNG in previous post).
Simon lives in a flat so even local Tx is difficult for him, and at this
stage of the project (protocol development) he really needs to test the
back to back interactions between two radios.
The HF/Mimo work sounds interesting, would love to see the papers!
Thanks,
David
On 2/5/21 12:27 pm, Ross Whenmouth wrote:
Hi David & Simon,
To start with, rather than using two back-back radios (presumably with
a large attenuation factor in the RF connection between the two), you
could use an HF channel simulator such as;
GNU Radio https://wiki.gnuradio.org/index.php/Channel_Model
<https://wiki.gnuradio.org/index.php/Channel_Model>
Ionos (Winlink) https://winlink.org/content/ionos_simulator
<https://winlink.org/content/ionos_simulator>
PathSim http://www.moetronix.com/ae4jy/pathsim.htm
<http://www.moetronix.com/ae4jy/pathsim.htm>
(CCIR has published standardised HF channel models (eg CCIR poor) with
which to configure your channel simulator)
Once you are ready to try out your modem "over the air", to start
with, you probably only need to set up a transmitter at your QTH as
you are blessed with access to a large number of public web SDRs
around continental Europe: http://rx.linkfanel.net/
<http://rx.linkfanel.net/>
Notably, there are nearby receivers in Karlsruhe and Stuttgart, and if
you are looking for a longer path (~450 km), the receiver at the
University of Twente, Enschede, Netherlands is a good option.
Karlsruhe http://sdr.pjs.de:8073/ <http://sdr.pjs.de:8073/>
Stuttgart http://dj9kaikiwi.ddns.net:8073/
<http://dj9kaikiwi.ddns.net:8073/>
" http://bat-server.dyndns.org:8073/
<http://bat-server.dyndns.org:8073/>
" http://dl2sba.ddns.net:8073/ <http://dl2sba.ddns.net:8073/>
University Twente http://websdr.ewi.utwente.nl:8901/
<http://websdr.ewi.utwente.nl:8901/>
PS: Some very interesting research into 2x2 MIMO for HF digital
channels has been performed recently - I can send you the papers if
you are interested.
73 ZL2WRW
Ross Whenmouth
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