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<div class="moz-cite-prefix">On 1/12/2023 11:29 AM, Jess Haas wrote:<br>
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cite="mid:CAHN_RKOfXh0tiF_58+78ahSfRMkwkqrRzZ1QGYBoKWnF1bYEVg@mail.gmail.com">
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<div>One of the cool things about software modems is that it is
possible for igates to receive multiple modes. I had a 70cm
digipeater/igate going for a bit that could receive 9600, 1200
or 300 baud. The idea was that if you couldn't get in but
needed to send something you could drop down to a more robust
mode.
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<div dir="auto">-Jess</div>
<div dir="auto">K5LLI</div>
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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>
<p>I am running my 60M HF igate with a 500-600 Hz IF filter
bandwidth (Yaesu FT-891 which does have a DSP continuously
variable IF), so the OFDM-500 mode is the only OFDM mode that
would work. I have already validated that the TX RSID works
consistently to switch between MFSK16 and PSK63. I could probably
depend on it to switch to OFDM500 as well. I.e. igate has
automatic multi-mode receive capability. <br>
</p>
<p>However, I would want to use two copies of UIview and two copies
of FLdigi to do this comparison test, so that I can used different
SSIDs on the two modes -- beaconing alternately so that I can map
the received posits separately on APRS.fi or findu.com. <br>
</p>
<p>I drive up to Traverse City semi-regularly for the Cherryland ARC
meetings, so I could repeat the test run again next month with the
dual FLdigi setup. <br>
</p>
<hr width="100%" size="2">Stephen H. Smith wa8lmf (at) aol.com <br>
Skype: WA8LMF<br>
EchoLink: Node # 14400 [Think bottom of the 2-meter band]<br>
Home Page: <a class="moz-txt-link-freetext" href="http://wa8lmf.net">http://wa8lmf.net</a><br>
<br>
-- APRS over FLdigi Modes --<br>
<a class="moz-txt-link-rfc2396E" href="http://wa8lmf.net//FLdigiAPRS/index.htm"><http://wa8lmf.net//FLdigiAPRS/index.htm></a><br>
<br>
60-Meter APRS! HF NVIS APRS Igate Now Operating<br>
<a class="moz-txt-link-rfc2396E" href="http://wa8lmf.ddns.net:14447/"><http://wa8lmf.ddns.net:14447/></a><br>
<br>
Flying Digipeater!<br>
<a class="moz-txt-link-rfc2396E" href="http://WA8LMF.net/FlyingDigi"><http://WA8LMF.net/FlyingDigi></a><br>
<br>
11 Copies of UIview in Action on One Computer! <br>
Live Off-The-Air APRS Activity Maps<br>
<a class="moz-txt-link-rfc2396E" href="http://wa8lmf.net/map"><http://wa8lmf.net/map></a><br>
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