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<div class="moz-cite-prefix">On 1/12/2023 12:44 PM, Stephen H Smith
via aprssig wrote:<br>
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cite="mid:b30f7a88-bf08-96d3-6fe7-e612dd6c8bd5@aol.com">
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<div dir="ltr" class="gmail_attr">On Thu, Jan 12, 2023,
5:15 PM Scott Howard <<a href="mailto:showard@nd.edu"
moz-do-not-send="true" class="moz-txt-link-freetext">showard@nd.edu</a>>
wrote:<br>
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<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">On
Wed, Jan 11, 2023 at 3:40 PM Stephen H Smith via aprssig<br>
<<a href="mailto:aprssig@lists.tapr.org"
target="_blank" rel="noreferrer"
moz-do-not-send="true" class="moz-txt-link-freetext">aprssig@lists.tapr.org</a>>
wrote:<br>
> YES! Here is the preliminary write-up on the
planned test in February.<br>
><br>
> <<a href="http://wa8lmf.net/APRS_VARA_MFSK/"
rel="noreferrer noreferrer" target="_blank"
moz-do-not-send="true" class="moz-txt-link-freetext">http://wa8lmf.net/APRS_VARA_MFSK/</a>><br>
<br>
Thanks, these are interesting results and I'm looking
forward to<br>
hearing how they go!<br>
<br>
After VARA HF was released, fldigi added "OFDM" modes
[1] which I<br>
believe are based on the same underlying idea as VARA.
If it is<br>
possible, it could be interesting to see how the fldigi
OFDM modes<br>
(e.g., OFDM500F) compare to VARA HF as well since fldigi
is common and<br>
open-source. <br>
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<p>I hadn't even noticed that recent releases of FLdigi did this
new mode (OFDM). I just tried switching my test setup written
up in the link above to OFDM500, and it seems to work just
fine. It's noticeably faster, taking 16 seconds including the
RSID. MFSK16 took 27.5 seconds to send the same compressed posit
and comment. But does OFDM tolerate weak noisy signals with
multipath as well???<br>
</p>
<p>You now have me curious. I'm going to have to gin up ANOTHER
test run running MFSK vs OFDM. Setup would be similar to my
described setup, but with TWO copies of FLdigi running from
separate folders instead of FLdigi vs VARA. <br>
</p>
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<p><br>
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<p>I've just done some table-top testing of OFDM and have now
re-jiggered the test setup to do ALL THREE modes alternately in
one outing. <br>
</p>
<p>On Feb 11, I will be beaconing alternately on VARA, MFSK-16 and
OFDM-500. The long-suffering Panasonic CF-51 Toughbook now has
THREE separate copies of UIview, VARA and two copies of FLdigi
working stably. It's currently beaconing ACOUSTICALLY (laptop
speaker-to-laptop mic) to a second laptop three feet away on the
table reliably for the last three hours.</p>
<p>I will do a test in my driveway next week when the weather is
supposed to warm up again to the upper '40s C. <br>
</p>
<p>I have revised my write-up on the Feb 11 experiment to reflect
the changes. <br>
</p>
<p> <a class="moz-txt-link-rfc2396E" href="http://wa8lmf.net/APRS_VARA_MFSK/"><http://wa8lmf.net/APRS_VARA_MFSK/></a></p>
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