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<p>In the aftermath of our cyclone here, I got dragged out for a bit
of media comment and, downstream, a few questions came up on dishy
power use. Here's what I know and can glean - comments welcome:</p>
<ul>
<li>Starlink's own specs say 50-75 W "Average Power Usage":
<a class="moz-txt-link-freetext" href="https://www.starlink.com/specifications">https://www.starlink.com/specifications</a>. But that's average, not
peak, and peak is what matters when people start recommending
that Starlink could be run out of a small inverter and a car
battery in a disaster. <br>
</li>
<li>Small inverters usually come with cigarette lighter cables,
and cigarette lighter sockets are typically fused with 8 or 10 A
fuses. That puts maximum safe power outputs in the 96W to
130-something W range depending on battery voltage.<br>
</li>
<li>Our lab's "RV" subscription rectangular dishy & router
regularly clocks in at around 80-100 W, and I've seen it go as
high as 108 W on one occasion. I've also seen it go as low as 30
W for the first time last night.<br>
</li>
<li>I have a user report from an older round dishy owner having
seen up to 200 W on occasion. <br>
</li>
<li>Assuming conservatively 90% inverter efficiency, that could
mean up to ~120W and maybe more for the rectangular version and
over 220 W for the circular one. <br>
</li>
<li>If dishy goes over cigarette lighter fuse capacity, people may
lose their ability to charge phones from their car - also a
critical capability in a disaster.</li>
<ul>
<li>Not everyone takes kindly to the suggestion that advising
inverter + car battery use could potentially be
counterproductive.<br>
</li>
</ul>
<li>So, what's the peak power use you have seen on your version of
dishy?</li>
<li>It appears that the current mode of operation here is that
dishy uses several satellites in parallel if these can all see a
gateway and have capacity to carry traffic. <br>
</li>
<ul>
<li>So for us in urban Auckland with few Starlink users in the
cell and three gateways in the vicinity, our dishy is spoiled
for choice and usually gets to use maybe three or more
satellites at once. That takes a corresponding amount of power
but also means great data rates a lot of the time. <br>
</li>
<li>For a rural user with more Starlink users in the cell and
further away from gateways, the satellites that the cell can
see and that can also see a gateway may be fewer in number.
This means dishy only gets to talk to maybe one or two birds
at a time and so uses a lot less power, and you get more
average data rates there.</li>
</ul>
<li>If this is so, then it begs a question:</li>
<ul>
<li>If Starlink could cap the number of satellites dishy can use
in an emergency area, they would be able to keep your fuse
intact. Should they aim for that, even if it means that you
might see lower data rates in a situation when many people
depend on one unit?</li>
</ul>
</ul>
<p>Starlink is currently being touted as THE comms solution for
emergencies as large swathes of NZ's northern and eastern North
Island remain without terrestrial or mobile Internet coverage
after cyclone Gabrielle. This is the outage map of one of the
larger mobile phone providers just for these areas:</p>
<p><img src="cid:part1.RKRqYfpq.ie1s964k@auckland.ac.nz" alt=""></p>
<p><img src="cid:part2.n3N7a0oh.uRi0KmHu@auckland.ac.nz" alt=""></p>
<p>Most of these are due to power outages to sites, but there are
quite a few backhaul cable issues as well.<br>
</p>
<p>One of the biggest problems is that electronic payment systems
don't work without Internet. In our largely cashless society, this
is leading to situations where emergency services can't refuel
their vehicles because their fuel cards won't work, supermarkets
and other stores can't sell anything because customers have no
means of paying, and the air force is flying in hard cash in order
to help the locals buy food.<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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