Le 13/11/2023 à 21:34, Ulrich Speidel via Starlink a écrit :
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.
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.
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.
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.
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.
Also, I'd check the label on the power supply unit of the dish box.
That tells how many Ampers - at a maximum - it can draw.
Alex
On 14/11/2023 5:22 am, Inemesit Affia via Starlink wrote:
You have to size power equipment for max power plus a percentage
regardless of current traffic needs.
Look for the ANATEL docs on Reddit you'll see it there(per dish at
least). Or search the NASASpaceflight forum.
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
Nov 13, 2023 5:10:27 PM J Pan <p...@uvic.ca>:
is the power consumption related to traffic volume? currently the
traffic is very light
https://www.reddit.com/r/StarlinkEngineering/comments/17k3jas/intergs_ground_station_satellite_links_much/
--
J Pan, UVic CSc, ECS566, 250-472-5796 (NO VM), p...@uvic.ca,
Web.UVic.CA/~pan <http://Web.UVic.CA/~pan>
On Sun, Nov 12, 2023 at 10:40 PM Inemesit Affia via Starlink
<starlink@lists.bufferbloat.net> wrote:
It's kinda expensive to run. Likely 75KW peak.
Check the power requirements for a regular gateway and divide
by two.
Might be useful for Taiwanese Islands though
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Dr. Ulrich Speidel
School of Computer Science
Room 303S.594 (City Campus)
The University of Auckland
u.spei...@auckland.ac.nz
http://www.cs.auckland.ac.nz/~ulrich/
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