From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from vsmx001.dclux.xion.oxcs.net (vsmx001.dclux.xion.oxcs.net [185.74.65.81]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 4B3663CB37 for ; Wed, 31 Aug 2022 06:12:52 -0400 (EDT) Received: from proxy-1.proxy.oxio.ns.xion.oxcs.net (proxy-1.proxy.oxio.ns.xion.oxcs.net [83.61.18.4]) by mx-out.dclux.xion.oxcs.net (Postfix) with ESMTPA id E36DF8C0449 for ; Wed, 31 Aug 2022 10:12:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=dclux.xion.oxcs.net; s=mail1; t=1661940771; bh=rF1mR+x05nAK79OXaw+g2Hd9/M24RsMhJjT2ljFVhCI=; h=Date:From:To:In-Reply-To:References:Subject:From; b=E3TyYePBEYDKuqW5bZoQmRIUJlAthp0vBYWzG6Cf1tCVnpB1bK07Upm8oLtBgSxg0 U4zJHmDt4LjNWndMGKFgc0Wdkb6G6m8Q/sYb3hesC/KFqDtqYuq6RxywCA/dU7cc6S UDkatMIsg7jvDF6v5+YrBsZFyyYtZAhrOlu8LT///NWUO0/+NDxTHjZM5AGyZy5I2e HDrzfN5i5CuaD7vJI3a1lpWo9FeTIaWPt6Oyp3DlViVLaRauToiaiImVVgJ2EIEIQ+ 1d8q7oSt87mABID9udnMZc3Xai2HJhXJlGY+UidquHX/VykTA5xdhRzZwq8qHwLu7i iu+aZUddxsBSw== Date: Wed, 31 Aug 2022 12:12:41 +0200 From: Mike Puchol To: starlink@lists.bufferbloat.net Message-ID: <58b24c5a-7280-4365-8cf7-5cdd42c7a930@Spark> In-Reply-To: References: <1661878433.14064713@apps.rackspace.com> <6p5n9262-3745-pq31-5636-1rnon987o255@ynat.uz> <20220830220710.GA2653@sunf10.rd.bbc.co.uk> <15982a40-2b34-7ed1-bfa3-bced03fc3839@auckland.ac.nz> <9CE05D69-FC37-4C97-9D8D-D46B2DF6DE16@gmx.de> <2321be3b-957f-2d1f-c335-119c8e76efe5@auckland.ac.nz> <8978587-42op-q175-2o41-qq9p4491459s@ynat.uz> X-Readdle-Message-ID: 58b24c5a-7280-4365-8cf7-5cdd42c7a930@Spark MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="630f3420_1849c29b_2eb" X-VadeSecure-Status: LEGIT X-VADE-STATUS: LEGIT Subject: Re: [Starlink] Starlink "beam spread" X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 31 Aug 2022 10:12:52 -0000 --630f3420_1849c29b_2eb Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline 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 beam= s on a cell, each on a different frequency, and a subset of terminals use= beam =231 as primary, =232 as backup, another subset use beam =233 as pr= imary, =234 as backup, and so on. Best, Mike On Aug 31, 2022, 12:06 +0200, David Lang , wrote: > I was actually referring to the possibility that the home dishy could p= oint 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 whi= ch 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, aroun= d 1.5=C2=BA to 2.5=C2=BA. SpaceX is working on =E2=80=9Cmega-gateways=E2=80= =9D where 32 antennas will co-exist. They are also deploying a new gatewa= y 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 , wrote: > > > On Wed, 31 Aug 2022, Ulrich Speidel via Starlink wrote: > > > > > > > This combines with the uncomfortable truth > > > > that an R=46 =22beam=22 from a satellite isn't as selective as a = laser beam, > > > > so the options for frequency re-use from orbit aren't anywhere ne= ar as > > > > good as from a mobile base station across the road: Any beam poin= ted at > > > > you can be heard for many miles around and therefore no other use= r can > > > > re-use that frequency (with the same burst slot etc.). > > > > > > not quite, you are forgetting that the antennas on the ground are a= lso steerable > > > arrays and so they can focus their 'receiving beam' at different sa= tellites. > > > This is less efficient than a transmitting beam as the satellites y= ou 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 > > > =5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F= =5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F > > > Starlink mailing list > > > Starlink=40lists.bufferbloat.net > > > https://lists.bufferbloat.net/listinfo/starlink > > > =5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F= =5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F > Starlink mailing list > Starlink=40lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/starlink --630f3420_1849c29b_2eb Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
This is what happens today. We know there is at lea= st 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 s= ubset of terminals use beam =231 as primary, =232 as backup, another subs= et use beam =233 as primary, =234 as backup, and so on.

Best,

Mike
On Aug 31, 2022, 12:06 +0200, David= Lang <david=40lang.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 a= re extremely narrow, around 1.5=C2=BA to 2.5=C2=BA. SpaceX is working on = =E2=80=9Cmega-gateways=E2=80=9D where 32 antennas will co-exist. They are= also deploying a new gateway design with a larger antenna, and thus narr= ower 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=40list= s.bufferbloat.net>, wrote:
On Wed, 31 Aug 2022, Ulrich Speidel via Sta= rlink wrote:

This combines with the uncomfortable truth<= br /> that an R=46 =22beam=22 from a satellite isn't as selective as a laser be= am,
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 st= eerable
arrays and so they can focus their 'receiving beam' at different satellit= es.
This is less efficient than a transmitting beam as the satellites you are= n'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 sa= me
time.

David Lang
=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F= =5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F
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