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<p>Caution - 250 kW peak sounds more like a horror movie (around 500
W average powers your average household) but there's an easy
explanation. It's also a good example for why Reddit isn't a good
source of information unless you know and can interpret what it is
that you're looking at. The figures you've seen are almost
certainly EIRP ones (effective isotropically radiated power). And
EIRP ain't the same as power consumption.</p>
<p>Simple example: Take a 100 W light bulb that radiates more or
less isotropically (same amount of light power in all directions)
without any reflectors etc. When you look at that light bulb, you
see 100 W EIRP. Put a mirror behind the lightbulb, so you now see
the bulb and its reflection, which looks like two bulbs. Makes 200
W EIRP, but it doesn't increase your power bill. A simple mirror
like that has a gain of 3 dBi.<br>
</p>
<p>At a Ku band frequency of 18 GHz, a 1.5 m diameter parabolic dish
has a gain of over 48 dBi. Each 3 dBi step in there effectively
doubles the number of transmitters you see reflected to you if
you're the receiver. 48 dBi means 16 such steps. So you have to
divide the EIRP of something like this by the "2^16" reflections
that this gives you. If you're having 250 kW EIRP, then the actual
transmit power is just a few watts, and similarly your power
consumption is a lot more modest. </p>
<p>Another way of looking at this is that what goes up (to the
satellite in terms of bits) has to come down (to another ground
station / dishy). That happens via a similar path. So if you'd
transmit to a satellite with anything like even 25 kW actual
transmitter power, you'd also need a similar amount of transmit
power at the satellite to downlink. And you'd have to generate
that power up there in orbit. Now I have solar PV, and I know that
generating a measly 5 kW peak takes 20 panels of around 2 sqm size
each. Generating the sort of power you'd need to transmit at 25 kW
would require solar arrays on the satellite that are more like the
size of a football field. Ballpark. </p>
<p>Thankfully EIRP for a dish of fixed size goes up as a linear
function of dish diameter and transmit frequency as the antenna
becomes more "pointed" as you move from conventional C band to the
Ku and Ka bands used by Starlink. <br>
</p>
<div class="moz-cite-prefix">On 14/11/2023 5:22 am, Inemesit Affia
via Starlink wrote:<br>
</div>
<blockquote type="cite" cite="mid:f1389497-7980-4c82-bbf2-eff46845929c@gmail.com">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<span dir="ltr" style="margin-top:0; margin-bottom:0;">You have to
size power equipment for max power plus a percentage regardless
of current traffic needs.</span> <br>
<br>
<span dir="ltr" style="margin-top:0; margin-bottom:0;">Look for
the ANATEL docs on Reddit you'll see it there(per dish at
least). Or search the NASASpaceflight forum.</span> <br>
<br>
<span dir="ltr" style="margin-top:0; margin-bottom:0;">I think
it's 250kw peak. Could be 25kw instead can't remember right. But
each dish is more than 5kw and there's other equipment than
dishes </span> <br>
<div>
<div dir="ltr">
<p>Nov 13, 2023 5:10:27 PM J Pan <a class="moz-txt-link-rfc2396E" href="mailto:Pan@uvic.ca"><Pan@uvic.ca></a>:</p>
</div>
<blockquote style="margin:0;border-left:3px solid #ccc; padding-left:10px">
<div> is the power consumption related to traffic volume?
currently the <br>
traffic is very light <br>
<a href="https://www.reddit.com/r/StarlinkEngineering/comments/17k3jas/intergs_ground_station_satellite_links_much/" moz-do-not-send="true">https://www.reddit.com/r/StarlinkEngineering/comments/17k3jas/intergs_ground_station_satellite_links_much/</a>
<br>
-- <br>
J Pan, UVic CSc, ECS566, 250-472-5796 (NO VM), <a class="moz-txt-link-abbreviated" href="mailto:Pan@UVic.CA">Pan@UVic.CA</a>,
<a href="http://Web.UVic.CA/~pan" moz-do-not-send="true">Web.UVic.CA/~pan</a> <br>
<br>
On Sun, Nov 12, 2023 at 10:40 PM Inemesit Affia via Starlink
<br>
<a class="moz-txt-link-rfc2396E" href="mailto:starlink@lists.bufferbloat.net"><starlink@lists.bufferbloat.net></a> wrote: <br>
<blockquote style="margin:0;border-left:3px solid #ccc; padding-left:10px"> <br>
It's kinda expensive to run. Likely 75KW peak. <br>
<br>
Check the power requirements for a regular gateway and
divide by two. <br>
<br>
Might be useful for Taiwanese Islands though <br>
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<br>
</blockquote>
</div>
</blockquote>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
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<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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