It's 20 km in diameter, roughly.
On 2/24/23 02:51, Ulrich Speidel via Starlink wrote:
Did you mean to say 20 km diameter or 20 km^2 area?
For those not familiar with RF engineering terms: A 3 dB contour as
Oleg shows it below in blue is the line where the power flux density
from the satellite drops to half of the value at the centre of the
beam. That's important as in RF engineering of cellular or beam
division networks, the minimum power you need to receive a signal
successfully can be several orders of magnitude larger than the amount
of power you need to cause interference to off-beam unintended
receivers. So in terms of their interference contour, beams are
actually much wider than just a cell or so, and a power flux density
half as high as at beam centre doesn't mean that it's the perimeter of
the beam as such - the beam will happily interfere with anyone up to a
few cells down the road at least.
Incidentally, I'm seeing Dishy use more power when it's receiving at
higher rates, which is what you'd expect if its DSP is busy digging
out intended signals from unintended ones.
On 24/02/2023 1:18 pm, Oleg Kutkov via Starlink wrote:
Yes. The cell size is ~20 km
On 2/24/23 02:08, David Lang wrote:
they can only narrow the radio beam so much (probably whatever their
cell size is). They can't change the footprint without changing the
antenna, so unless they have the beam move around in the cell, the
footprint should be slightly larger than the cell size
sometimes there is a lot of data going to one station, but sometims
it's only going to be a trival amount (think ack packets for a lot
of uploads), so they can save airtime by using one timeslot to
transmit to many stations at once.
David Lang
On Fri, 24 Feb 2023, Oleg Kutkov via Starlink wrote:
Date: Fri, 24 Feb 2023 01:47:05 +0200
From: Oleg Kutkov via Starlink <[email protected]>
Reply-To: Oleg Kutkov <[email protected]>
To: [email protected]
Subject: Re: [Starlink] System and method of providing a medium
access control
scheduler
Oh, that's interesting.
>> the satellite broadcasts the downlink radio frame to all the
user terminals in a group and they each retrieve their respective
data from the downlink radio frame
I thought the satellite beamformer only sends data frames to the
appropriate UT. It looks like the given satellite covers the whole
cell at one TX channel.
Otherwise, it would be too complex, I guess.
On 2/23/23 23:53, Dave Taht via Starlink wrote:
For those of you that don't look at patents, don't look at:
https://patents.justia.com/patent/11540301
But I would welcome comment from those that do.
H/T virtuallynathan.
--
Best regards,
Oleg Kutkov
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Dr. Ulrich Speidel
School of Computer Science
Room 303S.594 (City Campus)
The University of Auckland
[email protected]
http://www.cs.auckland.ac.nz/~ulrich/
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Best regards,
Oleg Kutkov
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