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<div class="moz-cite-prefix">OFDM is a pretty rectangular emission
spectrum (unless you're over-driving your amps), so it keeps
pretty tightly to its own frequencies. For example:<br>
<br>
<img class="decoded"
alt="http://www.dsplog.com/db-install/wp-content/uploads/2008/02/ofdm_tx_spectrum.png"
src="cid:part1.00080006.05000402@bartk.us"><br>
<br>
We haven't experienced issues with anyone above 5925 to date. The
spectrum up there is for fixed microwave (think: point-to-point
dishes) and earth-to-space (think: giant dishes pointed up). Both
types of usage are highly directional, so even if there is some
spill, it's unlikely to affect anything. I'm reluctant to
pro-actively give up already limited spectrum on the off chance
that some day we'll co-locate with a licensed transceiver that
does use a frequency low down near 5925 and our sideband is strong
enough and the antenna gains are correctly directional enough to
interfere. We do spectrum surveys of our sites before we install
anything, so that we can better predict if there will be issues.<br>
<br>
Good point though, and it has been considered during initial
planning.<br>
<br>
Aside from emission frequencies, there's also the consideration of
directionality (eg: F/B ratio). That's an area that we can use
lots of improvement in. I'm not happy with our present
performance there. I heard you guys are planning to use UBNT
sectors. We might use them too. Just be aware of their very
narrow vertical pattern. It means setting proper down-tilt is
critical. I really gotta measure them in full 3D, and with
WaveGuards.<br>
<br>
--Bart<br>
<br>
<br>
<br>
On 06/25/2014 12:30 PM, Tom Hayward wrote:<br>
</div>
<blockquote
cite="mid:CAFXO5Z1MgUPxpBzjcVyM+CuOU1MZ6dX7MxNuMAKDpfC3xhW5Jw@mail.gmail.com"
type="cite">
<pre wrap="">On Wed, Jun 25, 2014 at 12:27 PM, Kenneth Tolliver
<a class="moz-txt-link-rfc2396E" href="mailto:ktolliver@hotmail.com"><ktolliver@hotmail.com></a> wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Shouldn't the 10 MHz Plan be bumped down by 5 MHz(or some other amount) to
allow 5MHz as a Guard at the top of the Ham Band Plan? I don't know what is
on the other side of 5.925GHz; but I'd assume it could be an issue to us.
Has that been discussed before and I just missed it? Maybe just 1 or 2 MHz
would be sufficient?
</pre>
</blockquote>
<pre wrap="">
The guard bands were sized by testing. 10 MHz was decided on because
that was where throughput speeds were good even with 3 sectors
colocated.
There aren't going to be nearby transmitters on 5.926 GHz, so we have
no reason to bump the guard band down. We might as well use the full
ham band.
Tom KD7LXL
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</pre>
</blockquote>
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