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<p>Mike McGinty W2FBI is working on a ham radio band LTE
implementation. He has a demo running with a Band 40 femtocell
from China. Band 40 is 2300 to 2400 MHz TDD which overlaps the ham
band at 2300 to 2310 MHz.</p>
<p>He's concerned about the legality of LTE in the ham bands. The
first issue was if OFDM is legal. At this point in time, we all
agree that paragraph 97.307(f)(8) makes OFDM entirely legal above
51 MHz.</p>
<p>The other issues are how to ID and encryption. For ID, I claim
everyone running FT8 is violating 97.119(b), so it's moot.
Therefore, all you have to do for ID is send your call sign in the
clear somewhere in the signal.<br>
</p>
<p>Encryption is a bit of a can of worms. We believe there's a null
cipher available, but it needs to be tested. It's also believed
that some parts of the specification are always scrambled, so that
needs to be fully understood.</p>
<p>Mike has a Discord server for the project. E-mail me if you want
an invite.<br>
</p>
<p>Ron W6RZ<br>
</p>
<div class="moz-cite-prefix">On 4/24/25 19:39, Jan Schiefer via
Ground-Station wrote:<br>
</div>
<blockquote type="cite"
cite="mid:255F4181-E23E-4331-846A-60C5996ECE37@akalaitis.net">
<pre class="moz-quote-pre" wrap="">Is there somebody planning to experiment with OFDM-like signals for ham radio, or is this all purely hypothetical?
What I would find more interesting is multi-band carrier aggregation on HF. For example, simultaneously sending part of the signal on 80m and part on 40m, with some smart coding based on propagation characteristics at the time of the transmission. In theory, this should give you a pretty robust signal on e.g. NVIS.
Would something like this be subject to the same questions as far as the legality goes?
And I am sure there is another can of worms on this shelf with the label “MIMO” on it. Maybe let’s keep this one where it is.
Cheers,
Jan, ac7td
</pre>
</blockquote>
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