[Starlink] Starlink "beam spread"

[Mike Puchol]

This is what happens today. We know there is at least a primary beam and a backup beam, and the terminal can pick the backup if it feels necessary (eg. the primary becomes obstructed). Technically, you could have 8 beams on a cell, each on a different frequency, and a subset of terminals use beam #1 as primary, #2 as backup, another subset use beam #3 as primary, #4 as backup, and so on.

Best,

Mike
On Aug 31, 2022, 12:06 +0200, David Lang <david at lang.hm>, wrote:
> I was actually referring to the possibility that the home dishy could point at
> different satellites, so you could have multiple satellites pointing at a given
> cell on the same frequency, and the dishy can aim it's beam to pick which one to
> hear as well as which one to transmit to.
>
> David Lang
>
> On Wed, 31 Aug 2022, Mike Puchol via Starlink wrote:
>
> > On this particular one, the gateway beams are extremely narrow, around 1.5º to 2.5º. SpaceX is working on “mega-gateways” where 32 antennas will co-exist. They are also deploying a new gateway design with a larger antenna, and thus narrower beamwidth and more gain, allowing for a considerable reduction in TX power.
> >
> > Best,
> >
> > Mike
> > On Aug 31, 2022, 09:33 +0200, David Lang via Starlink <starlink at lists.bufferbloat.net>, wrote:
> > > On Wed, 31 Aug 2022, Ulrich Speidel via Starlink wrote:
> > >
> > > > This combines with the uncomfortable truth
> > > > that an RF "beam" from a satellite isn't as selective as a laser beam,
> > > > so the options for frequency re-use from orbit aren't anywhere near as
> > > > good as from a mobile base station across the road: Any beam pointed at
> > > > you can be heard for many miles around and therefore no other user can
> > > > re-use that frequency (with the same burst slot etc.).
> > >
> > > not quite, you are forgetting that the antennas on the ground are also steerable
> > > arrays and so they can focus their 'receiving beam' at different satellites.
> > > This is less efficient than a transmitting beam as the satellites you aren't
> > > 'pointed' at will increase your noise floor, but it does allow the same
> > > frequency to be used for multiple satellites into the same area at the same
> > > time.
> > >
> > > David Lang
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> >
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