Starlink : General Discussion - Thread 2

[Asteroza]

SpaceX has updated their https://www.starlink.com/ website (now multiple languages are available) and some new and updated renders were added.

Uh, is that overall shot of the sat showing only two end lasers and one side laser on the top? So only 3 lasercomm terminals?

[Yiosie]

SpaceX: Chip shortage is impacting “our ability to fulfill” Starlink orders [dated Nov. 1]

Starlink exits beta, but "silicon shortages have delayed production."

If you ordered Starlink broadband service and don't receive your "Dishy McFlatface" satellite dish any time soon, the global chip shortage may be one reason why.

"Silicon shortages have delayed production which has impacted our ability to fulfill orders. Please visit your Account page for the most recent estimate on when you can expect your order to be fulfilled," SpaceX said in an FAQ on the Starlink support website. The language was added to the Starlink website on Thursday night, according to a PCMag article.

Starlink has apparently just exited its beta status. SpaceX CEO Elon Musk said in September that it would emerge from beta in October, and the word "beta" was deleted from descriptions on the Starlink homepage late last week. The website was also updated to advertise "download speeds between 100Mbps and 200Mbps and latency as low as 20ms in most locations," an improvement over the previously stated "50Mbps to 150Mbps and latency from 20ms to 40ms in most locations."

But the move from beta to general availability doesn't necessarily coincide with widespread availability. PCMag also pointed out that expected shipment times for Starlink have been pushed to late 2022 or early 2023 in additional parts of the US. The Starlink website reports expected service times of "early to mid 2022" in other areas.

[TheRadicalModerate]

SpaceX has updated their https://www.starlink.com/ website (now multiple languages are available) and some new and updated renders were added.

Uh, is that overall shot of the sat showing only two end lasers and one side laser on the top? So only 3 lasercomm terminals?

Huh.  I only see 3 as well.  I wonder if the fourth one could be hiding under (or above, depending on your frame of reference) the dark visor next to the compression fitting on the long edge.

If you had the ability to yaw the attitude 180º on alternate birds in each plane, you could probably get away with only three ISLs.  You could then route traffic to either of the neighboring planes, even though you might have to hop forward or backward one bird in the current plane before doing so, if your long-edge laser was pointed in the wrong direction.

But this would imply that the solar panels would have to rotate about their long axes, I think.  We know they're capable of folding flat into "open book" mode, so maybe this isn't completely implausible?

Another question:  Are the flaps to either side of the long-edge compression fitting all that remains of the "visors"?

[Asteroza]

SpaceX has updated their https://www.starlink.com/ website (now multiple languages are available) and some new and updated renders were added.

Uh, is that overall shot of the sat showing only two end lasers and one side laser on the top? So only 3 lasercomm terminals?

Huh.  I only see 3 as well.  I wonder if the fourth one could be hiding under (or above, depending on your frame of reference) the dark visor next to the compression fitting on the long edge.

If you had the ability to yaw the attitude 180º on alternate birds in each plane, you could probably get away with only three ISLs.  You could then route traffic to either of the neighboring planes, even though you might have to hop forward or backward one bird in the current plane before doing so, if your long-edge laser was pointed in the wrong direction.

But this would imply that the solar panels would have to rotate about their long axes, I think.  We know they're capable of folding flat into "open book" mode, so maybe this isn't completely implausible?

Another question:  Are the flaps to either side of the long-edge compression fitting all that remains of the "visors"?

Could it be a move so that sats in the same plane alternate between left and right ISL's? That would be a big cost/mass reduction for what should be a relatively minor operational complication (retargeting the side ISL when near the earth's poles). Would that substantially increase the wear and tear on the side lasercomm beam director motors, over a 4 ISL configuration though? Or would good handoff planning between all 3 (or 4) reduce the fast pointing changes incurred at max latitude?

But wait a second, the illustrated thruster is on the long side with the ISL right? If thrusting for orbit maintenance, you have to turn broadside at (relatively) max cross section. In that configuration, the end ISL's have free shots front and back along the plane, and the side ISL gets a rearward limited hemisphere line of sight (allowing both LEFT and RIGHT operation roughly).

[TheRadicalModerate]

Huh.  I only see 3 as well.  I wonder if the fourth one could be hiding under (or above, depending on your frame of reference) the dark visor next to the compression fitting on the long edge.

If you had the ability to yaw the attitude 180º on alternate birds in each plane, you could probably get away with only three ISLs.  You could then route traffic to either of the neighboring planes, even though you might have to hop forward or backward one bird in the current plane before doing so, if your long-edge laser was pointed in the wrong direction.

But this would imply that the solar panels would have to rotate about their long axes, I think.  We know they're capable of folding flat into "open book" mode, so maybe this isn't completely implausible?

Another question:  Are the flaps to either side of the long-edge compression fitting all that remains of the "visors"?

Could it be a move so that sats in the same plane alternate between left and right ISL's? That would be a big cost/mass reduction for what should be a relatively minor operational complication (retargeting the side ISL when near the earth's poles). Would that substantially increase the wear and tear on the side lasercomm beam director motors, over a 4 ISL configuration though? Or would good handoff planning between all 3 (or 4) reduce the fast pointing changes incurred at max latitude?

But wait a second, the illustrated thruster is on the long side with the ISL right? If thrusting for orbit maintenance, you have to turn broadside at (relatively) max cross section. In that configuration, the end ISL's have free shots front and back along the plane, and the side ISL gets a rearward limited hemisphere line of sight (allowing both LEFT and RIGHT operation roughly).

I assume that the satellites are operational in shark fin mode (solar array +r, edge to flight path), so the two ISLs on the short ends do indeed point to the leading and trailing birds in the same plane.

Maybe the ISL on the wide end swings down and can rotate to be either left or right?  If so, I suspect that wear-and-tear issues would indeed dictate that it stays oriented that way, more or less.  There's certainly no way that you have it pivot on a packet-by-packet basis.

In general, the angular change on the left and right is pretty gradual, but the nearest left bird will cross over to the right hand side at max latitude and vice versa.  I don't know if there'd be more travel of the beam mechanism following it across or whether it would pick up a bird crossing from right to left.

Either way, if you have alternating left-pointing and right-pointing birds in along the same plane, the trick is that routing packets is still easy:  if the packet needs to go east and the ISL is covering west, forwarding one hop forward or back gets you to an east-pointing ISL, and the packet will make its way against the grain until it gets where it's going.

I guess the other possibility is that, when the constellation is more mature, all against-the-grain traffic could get forwarded up to the high-altitude constellation, which could be a completely different kind of satellite with zillions of ISLs and now RF to speak of.

I don't know what happens with raising altitude.  It might be easiest just to take the bird out of service during that.

[Chris Bergin]

Whoa! Long thread. Thanks to the report to mod alerting about that. Will start a new thread later today.

[vsatman]

Huh.  I only see 3 as well.  I wonder if the fourth one could be hiding under (or above, depending on your frame of reference) the dark visor next to the compression fitting on the long edge.

if we look on this photo .. (first 10 sats to polar orbit) I don`t find place for  3th anf 4th SpaceLaser

[Asteroza]

Huh.  I only see 3 as well.  I wonder if the fourth one could be hiding under (or above, depending on your frame of reference) the dark visor next to the compression fitting on the long edge.

if we look on this photo .. (first 10 sats to polar orbit) I don`t find place for  3th anf 4th SpaceLaser

That pic shows the polar Gen 1 sat, which appears to have two lasercomm beam director barrels oriented fore/aft along the outside long edge, with the beam director heads on the same outer edge corners. I'm not sure if we have seen a clear shot of the inner edge of the satellite, aside from payload release video? Was it ever confirmed if there were more than 2 lasercomm terminals installed?

The render appears to show Gen 2, with the beam director barrels aligned on the short edge instead, with the twisting heads on opposite corners (and the third beam director on the inner long edge with the head on the edge, so limited to a side hemisphere line of sight).

[Robotbeat]

Three lasers is sufficient.

Connected like:

   |       |
---o---o---o---o---
       |       |
---o---o---o---o---
   |       |

[TheRadicalModerate]

Three lasers is sufficient.

Connected like:

   |       |
---o---o---o---o---
       |       |
---o---o---o---o---
   |       |

Yup, that's what I was trying to describe.

But if the long-edge laser can only reach targets on the side on which it's mounted, then that means that alternating satellites have to be yawed 180º from each other, which puts their solar panels pointing in opposite directions as well, and half of the birds won't get enough power.  If the panels can rotate about the z (or r) axis, then everything's cool.  But if they can't rotate, then flipping the birds around won't work.

On the other hand, if the long-edge laser can swing down below the satellite to reach targets on the other side of the bird, then the birds can all have the same orientation, and there's no solar panel problem.

[niwax]

You can also use tiled triangles for a tighter grid, depending on whether the lasers can turn far enough to allow it.

[cosmicvoid]

Got my Starlink kit a few days ago... [snip]

How's your installation been going? I've installed everything pretty easily, but I wonder maybe I did something wrong or it's just a bad connection with this technology. Anyway, it's cool to have and I hope it will be developed for the better condition

It's been working pretty well, no complaints. The outages are really not a problem, particularly with the failover to DSL, so I mostly ignore it when I infrequently have to wait 30 seconds to re-load a web page or rejoin a Zoom meeting.

Based on my initial obstruction reports, I have trimmed a couple of trees in the North view. Will see if that makes any noticeable difference. I installed the Ookla speedtest app on my desktop, and the pings have always been <40ms, and the speeds are typically 40-270Mb/s down and 8-40Mb/s up. Without knowing your equipment, location, and sky-view, I can't offer a reason why you might have a "bad connection".

Wondering how a wet/snowy PNW winter will affect things. So, my conclusion so far: I love it. When more satellites are deployed, it can only get better, IMHO.

[vsatman]

"The Bandwidth Of  The StarLink Constellation  and the assessment of its potential subscriber base in the USA".
SatMagazine, November 2021
pages 54...57  http://www.satmagazine.com/download.php

[envy887]

"The Bandwidth Of  The StarLink Constellation  and the assessment of its potential subscriber base in the USA".
SatMagazine, November 2021
pages 54...57  http://www.satmagazine.com/download.php

What is the theoretical maximum SNR for a Dishy-sized array? That article notes SNRs up to 12.5, but it's dubious that SpaceX would submit modulations up to QAM64 to FCC if they couldn't eventually get the needed SNR to run that modulation. I have a very early dish (the hardware build is noted as rev1_pre_production in debug) and the SNR never went above 9, which indicates to me that the hardware has since changed to increase SNR. SNR is no longer available in the app or in debug.

Also, why aren't they using the 2nd polarization? With the usage assumptions in that article (which are generally reasonable), the current ~1600-sat constellation would serve 550k US users with only UT changes to allow QAM64 and the 2nd polarization.

[vsatman]

What is the theoretical maximum SNR for a Dishy-sized array?

According to my calculations, 13.64 dB for the case when the satellite is shining at the terminal with 48 cm diameter at a 90 degrees elevation angle .
 In this case, it works 100% of terminal`s  square. But if the elevation angle is less than 90 degrees ,  then % the working area is equal to the sinus of the elevation angle..
  For 60 degrees this 84% ,  for  30 degrees only 50%..... and really  SNR will be less..

[envy887]

What is the theoretical maximum SNR for a Dishy-sized array?

According to my calculations, 13.64 dB for the case when the satellite is shining at the terminal with 48 cm diameter at a 90 degrees elevation angle .
 In this case, it works 100% of terminal`s  square. But if the elevation angle is less than 90 degrees ,  then % the working area is equal to the sinus of the elevation angle..
  For 60 degrees this 84% ,  for  30 degrees only 50%..... and really  SNR will be less..

The dish is 59 cm.

[su27k]

Shift4 stock surges after company signs payments deal with SpaceX’s Starlink

* Shares of payments processing company Shift4 surged in trading on Wednesday after the company announced a five-year partnership with SpaceX’s Starlink satellite internet service.

* “Starlink is a cornerstone, global client opening up opportunity throughout the globe. By servicing the business globally, Shift4′s [total addressable market] expands in all the verticals we serve,” the company said.

* Jared Isaacman, founder and CEO of Shift4, notably became an astronaut when he flew to orbit with SpaceX in September on the historic Inspiration4 private mission

Note this is just SpaceX using Shift4 to process user payments for Starlink.

[Asteroza]

What is the theoretical maximum SNR for a Dishy-sized array?

According to my calculations, 13.64 dB for the case when the satellite is shining at the terminal with 48 cm diameter at a 90 degrees elevation angle .
 In this case, it works 100% of terminal`s  square. But if the elevation angle is less than 90 degrees ,  then % the working area is equal to the sinus of the elevation angle..
  For 60 degrees this 84% ,  for  30 degrees only 50%..... and really  SNR will be less..

The dish is 59 cm.

How about the new dish?

[Asteroza]

Rondaz had been posting about the 10 Transporter-1 polar starlink sats being dropped in the orbit update thread, which seemed unusual.

Christian Frhr. von der Ropp on LinkedIn made an interesting comment that SDA had warned about rad hardness of lasercomm terminals for the Transport Layer constellation, and the deorbit oddly seems to coincide with the spike in solar flares around October 26

https://www.linkedin.com/feed/update/urn:li:activity:6864150263997972480/

Did those sats really suffer more than previous Starlink sats? Was that a function of the polar orbit/solar flare combo? Were only the LCT's damaged?

They are clearly operational enough to perform deorbit for now...

[soltasto]

Rondaz had been posting about the 10 Transporter-1 polar starlink sats being dropped in the orbit update thread, which seemed unusual.

Christian Frhr. von der Ropp on LinkedIn made an interesting comment that SDA had warned about rad hardness of lasercomm terminals for the Transport Layer constellation, and the deorbit oddly seems to coincide with the spike in solar flares around October 26

https://www.linkedin.com/feed/update/urn:li:activity:6864150263997972480/

Did those sats really suffer more than previous Starlink sats? Was that a function of the polar orbit/solar flare combo? Were only the LCT's damaged?

They are clearly operational enough to perform deorbit for now...

SpaceX also deorbited the functional v0.9 satellites just because they weren't useful for the full constellation. Those Transporter-1 satellites were pretty much test satellites with lasers, so it is not unlikely that they just completed their tests and now they are not useful anymore. Why aren't they useful anymore? While the assertion that the links were damaged by the solar flare is a possibility, that guess comes from a SpaceX competitor that has all interest in putting SpaceX in bad light, so the worst possibility (SpaceX forgetting about radiation) automatically becomes the only possibility to talk about for them.

There are many more possible reasons for SpaceX to deorbit them:
Incompatible HW with the new satellites
Compatible HW but much lower performance compared tot he new ones, would bottleneck the system
Any other issue whatsoever with the ISL HW that could have popped up regardless of the solar flare, ranging from power issues, cooling/heating issue, alignment issues...