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In his first Starlink simulation, Mark Hadley assumed five transponders per satellite -- Two in-plane, two adjacent, and one crossing:
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<div class="ContentPasted0">https://www.youtube.com/watch?v=3479tkagiNo&list=PLrRMhEONgz06oMXQOljB5BoZxZw6cShLN&index=3</div>
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<div class="ContentPasted0">In his next Starlink simulation, Mark Hadley assumed four:</div>
<div class="ContentPasted0">https://www.youtube.com/watch?v=QEIUdMiColU&list=PLrRMhEONgz06oMXQOljB5BoZxZw6cShLN&index=2</div>
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<div><span class="ContentPasted2" style="display: inline !important; background-color: rgb(255, 255, 255);">I guess he assumed the relative velocities were too high for the crossing connection.</span><br>
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<div class="ContentPasted0">I asked Bard "How many laser transponders are in a second-generation Starlink satellite?" and it said "four."</div>
<div class="ContentPasted0">I asked ChatGPT "How many laser transponders are in a second-generation Starlink satellite?" and it said it did not know.</div>
<div class="ContentPasted0">I asked Bard again and the second time it said it did not know.</div>
<div class="ContentPasted0">When I pointed out that it had told me "four" the first time I asked, Bard apologized for its previous answer.</div>
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<div class="ContentPasted0">I remain an "AI" skeptic:</div>
<div class="ContentPasted0 ContentPasted1"><a href="https://circleid.com/posts/20230721-google-bard-fails-to-answer-satellite-internet-questions" data-auth="NotApplicable" id="OWA0a32f77b-3766-6d9c-ce67-5476bd9e7e3e" class="OWAAutoLink">https://circleid.com/posts/20230721-google-bard-fails-to-answer-satellite-internet-questions</a><br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size: 11pt; color: rgb(0, 0, 0);"><b>From:</b> Starlink <starlink-bounces@lists.bufferbloat.net> on behalf of David Lang via Starlink <starlink@lists.bufferbloat.net><br>
<b>Sent:</b> Friday, September 22, 2023 1:41 AM<br>
<b>To:</b> Alexandre Petrescu <alexandre.petrescu@gmail.com><br>
<b>Cc:</b> starlink@lists.bufferbloat.net <starlink@lists.bufferbloat.net><br>
<b>Subject:</b> Re: [Starlink] APNIC56 last week</font>
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<div class="PlainText">I believe that I read that STarlink has 5 lasers per sat. but whatever the
<br>
number, it's a tiny number compared to the number of satellites that they have <br>
up there.<br>
<br>
As you are looking at 'trains', check their altitude. They aren't going to <br>
shuffle sats around much, it's expensive in terms of fuel and they are only <br>
allowed to provide service when they are in their proper orbits.<br>
<br>
We know the lasers are in operation as they are providing service to places more <br>
than one sat hop away from ground stations. We also know they have a lot of <br>
ground stations around to share the load.<br>
<br>
We have almost no details on the specific modules they are using, and none on <br>
what routing they are using.<br>
<br>
David Lang<br>
<br>
<br>
On Fri, 22 Sep 2023, <br>
Alexandre Petrescu via Starlink wrote:<br>
<br>
> Date: Fri, 22 Sep 2023 10:26:26 +0200<br>
> From: Alexandre Petrescu via Starlink <starlink@lists.bufferbloat.net><br>
> Reply-To: Alexandre Petrescu <alexandre.petrescu@gmail.com><br>
> To: starlink@lists.bufferbloat.net<br>
> Subject: Re: [Starlink] APNIC56 last week<br>
> <br>
><br>
> Le 21/09/2023 à 21:05, Inemesit Affia via Starlink a écrit :<br>
>> Not going to go into details but lasers have been identified in photos <br>
>> of the sats and one of the component suppliers is known. (The scale is <br>
>> novel, not the tech, demisabiliy is new though)<br>
><br>
> 4 or 2 lasers on each sat (N-S, E-W) is potentially a very different <br>
> matter from an IP routing standpoint. It still is a reduced set of <br>
> variables, for a routing protocol (it is not like there being an <br>
> arbitrary number of IP interfaces, it's just 2 or 4).<br>
><br>
> For component manufacturers: yes, I heard about a few manufacturers of <br>
> such equipment for laser comms for LEO sats, experimented. There is <br>
> public information about a few of them. I dont know which is considered <br>
> by starlink, but there is not my worry. There is also a difference <br>
> between laser links between sats on different orbit altitudes (e.g. <br>
> laser for ISL for GEO to MEO) and lasers between sats on a same orbit <br>
> altitude, or on a same orbit. It's three different things, with <br>
> different sets of requirements: focusing, power levels, distance ranges.<br>
><br>
> At the lowest limit (cheapest, less powerful, less range distance), I <br>
> suppose it is possible to use simply LiFi optical links (a sort of WiFi <br>
> but with light). If so, then it is very easy to have IP on it.<br>
><br>
> There is also an 'optical' spec that was circulated here on this list <br>
> (https://urldefense.com/v3/__https://www.sda.mil/wp-content/uploads/2022/04/SDA-OCT-Standard-v3.0.pdf__;!!P7nkOOY!pso4rogBStK7jR7pEg21ACCfJyL_ZCltZip5K7pxmJhmaSKfOY1RgwXzW4EtPOvEhS9XoLRaKS8QbVoEgYhXDWmzfQ$ ),
<br>
> although it seemed to me to figure on kepler's website, not on <br>
> starlink's. In that spec, it is said Ethernet, among other things. On <br>
> Ethernet, IP can run easily.<br>
><br>
>><br>
>> Starlink can't deliver to Antarctica or Northern parts of Alaska, <br>
>> Ascension Island, Diego Garcia, Easter Island, Vanuatu, Iran without <br>
>> ISL's etc<br>
><br>
> I'll have to look where these places are.<br>
><br>
> When looking at starlink satellites I often see trains forming and <br>
> lasting for a while. Someone said these sats are like that (trains) <br>
> prior to be put on a more evenly distanced, in-orbit; but some time <br>
> passed, and they continue this kind of behaviour: form denser trains, <br>
> then distance more evenly, and back again. So I am not sure these <br>
> 'trains' are ephemeral. They seem to be in such 'train' structure while <br>
> above some particular continents or areas, but not sure. It takes a lot <br>
> of time to make a meaning of it.<br>
><br>
> Also, now here are at least two kinds of starlink subscription plans: <br>
> 40EUR/month and 287EUR/month, for fixed vs mobile.<br>
><br>
>><br>
>> North South links seem to work but not East West (if they exist)<br>
><br>
> Yes, good question. It makes a lot of difference whether there are 2 or <br>
> 4 laser links on each sat. It also makes a lot of difference if trying <br>
> to make IP routing work there (assuming there could be 2 or 4 IP <br>
> interfaces for lasers).<br>
><br>
> This (number of ISL links on a starlink sat) can have an impact on how <br>
> people show LEO satellite topologies in Internet Drafts at IETF.<br>
><br>
> Alex<br>
><br>
>><br>
>> On Thu, Sep 21, 2023, 2:20 PM Alexandre Petrescu via Starlink <br>
>> <starlink@lists.bufferbloat.net> wrote:<br>
>><br>
>><br>
>> Le 19/09/2023 à 06:39, Ulrich Speidel via Starlink a écrit :<br>
>> > FWIW, I gave a talk about Starlink - insights from a year in -<br>
>> at last<br>
>> > week's APNIC56 conference in Kyoto:<br>
>> ><br>
>> > <a href="https://urldefense.com/v3/__https://conference.apnic.net/56/program/program/*/day/6/technical-2/__;Iw!!P7nkOOY!pso4rogBStK7jR7pEg21ACCfJyL_ZCltZip5K7pxmJhmaSKfOY1RgwXzW4EtPOvEhS9XoLRaKS8QbVoEgYjUChNXHQ$" data-auth="NotApplicable" id="OWA6a162a07-c5cf-a838-1804-aa521062c0ad" class="OWAAutoLink">
https://urldefense.com/v3/__https://conference.apnic.net/56/program/program/*/day/6/technical-2/__;Iw!!P7nkOOY!pso4rogBStK7jR7pEg21ACCfJyL_ZCltZip5K7pxmJhmaSKfOY1RgwXzW4EtPOvEhS9XoLRaKS8QbVoEgYjUChNXHQ$</a>
<br>
>><br>
>><br>
>> Thanks for the presentation.<br>
>><br>
>> I would like to ask what do you mean by "Method #2: "space<br>
>> lasers""and<br>
>> "Not all Starlink satellites have<br>
>> lasers" on slide 5?<br>
>><br>
>> It seems to be saying there is inter-satellite communications. The<br>
>> need<br>
>> of that seems to stem from the lack of ground 'teleport' that is<br>
>> necessary for DISHY-SAT-Internet communications, so a SAT-to-SAT<br>
>> communication is apparently used with lasers. I can agree with<br>
>> the need.<br>
>><br>
>> What standard is used for these lasers?<br>
>><br>
>> Is this ISL communicaiton within the starlink constellation a<br>
>> supposition or a sure thing?<br>
>><br>
>> Other presentations of starlink mentioned on this list dont talk<br>
>> about<br>
>> this lasers between sats (dont show lasers on the sats), but kepler<br>
>> talks about optical links, and also there is talk about ISOC LEO<br>
>> Internet about such 'lasers from space'.<br>
>><br>
>> (I must say that I thought previously that there were only 2 or 3<br>
>> ground<br>
>> teleports overall in EU and USA, but I see now there is a teleport<br>
>> in NZ<br>
>> too).<br>
>><br>
>> (for price comparison: it is said 100USD monthly, but in France right<br>
>> now the monthly subscription is at around 40 Euros; this competes<br>
>> very<br>
>> advantageously to other satcoms ISPs for rural areas non-covered<br>
>> by 5G;<br>
>> the cellular monthly subscriptions are still much more advantageous,<br>
>> where there is 5G, of course).<br>
>><br>
>> Alex<br>
>><br>
>> ><br>
>> > Also well worth looking at is Geoff Huston's excellent piece on the<br>
>> > foreseeable demise of TCP in favour of QUIC in the same session.<br>
>> One<br>
>> > of Geoff's main arguments is that the Internet is becoming local,<br>
>> > i.e., most traffic goes between a CDN server and you, and most<br>
>> data is<br>
>> > becoming proprietary to the application owner, meaning it suits the<br>
>> > Googles and Facebooks of this world very well not to be using<br>
>> TCP for<br>
>> > its transport, but rather pull the transport specifics into the<br>
>> > application layer where the have full control.<br>
>> ><br>
>> > Food for thought, especially since LEO networks are a<br>
>> particularly bad<br>
>> > place to put local content caches, since the concept of what's<br>
>> "local"<br>
>> > in a LEO network changes constantly, at around 20,000 miles an<br>
>> hour or<br>
>> > so. Spoke to a Rwandan colleague who installs Starlink there and<br>
>> sees<br>
>> > all traffic to anywhere go via the US with RTTs of nearly 2<br>
>> seconds,<br>
>> > even if the Rwandan user is trying to access a Rwandan service.<br>
>> ><br>
>> > About to hop onto a plane (ZK-NZJ) tonight with free WiFi (Ka band<br>
>> > GEO) enroute to Auckland in the hope of getting a better experience<br>
>> > than last time when the system seemed to run out of IP addresses on<br>
>> > its DHCP.<br>
>> ><br>
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