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.

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 <starlink@lists.bufferbloat.net>
Reply-To: Oleg Kutkov <contact@olegkutkov.me>
To: starlink@lists.bufferbloat.net
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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