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<div class="moz-cite-prefix">On 15/09/2023 11:29 pm, Alexandre
Petrescu via Starlink wrote:<br>
</div>
<blockquote type="cite" cite="mid:2012b68c-2e15-4b5c-b36b-3b1d7eff12b4@gmail.com">
<br>
I must say that I dont know whether the original 'DISHY' is simply
a<br>
dish antenna with an analog amplifier and maybe some mechanical
motor<br>
steering, or whether DISHY includes a computer to execute some
protocol,<br>
some algorithm.<br>
</blockquote>
<p>It's a phased array, not a dish, even if it looks like one. It
consists of 100's of fingernail-sized antenna elements that:</p>
<ul>
<li>during transmissions, have an individual phase delay added to
the signal transmitted from that element, in order to permit
transmission of the combined signal from all elements into a
particular direction.</li>
<li>during reception, have an individual phase delay added to the
signal collected by that element, before the signals are added
to obtain the combined received signal. This allows reception
from a particular direction.</li>
</ul>
<p>Dishy's main direction of transmission / reception is therefore
not its surface normal - this simply points to the area of the sky
where Dishy expects to see most satellites (a function of
geographical latitude and constellation design - essentially
straight up in the tropics, and elsewhere in the direction of the
53rd parallel, which corresponds to the predominant orbital
inclination in the Starlink fleet). The actual tracking is then
done with the phased array without mechanical movement by Dishy.<br>
</p>
<p>From what I've seen, Dishy seems to consume more power on receive
than on transmit - that's if you actually download stuff. This is
somewhat counter-intuitive if you're used to putting link budgets
together. But I'd attribute that to a higher degree of digital
signal processing required on the receive and demodulation path. <br>
</p>
--
<pre class="moz-signature" cols="72">****************************************************************
Dr. Ulrich Speidel
School of Computer Science
Room 303S.594 (City Campus)
The University of Auckland
<a class="moz-txt-link-abbreviated" href="mailto:u.speidel@auckland.ac.nz">u.speidel@auckland.ac.nz</a>
<a class="moz-txt-link-freetext" href="http://www.cs.auckland.ac.nz/~ulrich/">http://www.cs.auckland.ac.nz/~ulrich/</a>
****************************************************************
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