6 ms·

Interesting. I didn't know that coverage was limited. I assumed satellite == pretty much all of earth.

plasticchris 4y ago
It will once they get the laser terminals up and running so the sats can talk to each other
xxpor 4y ago
They can't do satellite to satellite yet. Just terminal -> sat -> ground station. Starlink is in low earth orbit, so the visibility any one satellite has is (relatively speaking) pretty limited.
ortusdux 4y ago
The majority of their satellites just bounce the signals back down to a nearby ground station. Their version 1.5 sats, which they started launching about a year ago, include laser links to allow sat->sat communication. Their plan is for the remaining 3/4th of their fleet to have laser links. One interesting side-effect of the laser links is that they can open up connections between stock exchanges and trading houses that are faster than direct fiberoptic lines. Milliseconds count in high frequency trading.
- foobiekr 4y ago
  Predictability and stability count a lot as well. I think the starlink-as-low-latency-trading-medium is sort of like "blockchain for real estate" - it's not actually a real thing.
  - vardump 4y ago
    You can simply use multiple links to send same data. The fastest one wins, so if there's a temporary hickup on one of the links, you still get somewhat bounded latency. When things work fine, you get to reap the latency benefit. So I think it's plausible for intercontinental links.
    - foobiekr 4y ago
      the spot still covers the same ground station much of the time.
- pclmulqdq 4y ago
  The traders are already using HF radios with lower latency.
  - rtkwe 4y ago
    Yeah SpaceX will have a very hard time beating the current routes; they're further from the surface and the intersatellite links won't be travelling in a straight line all the time. The best bet is if they can provide those links across oceans that can't be rigged with microwave towers.
    - pclmulqdq 4y ago
      The HF radios are transatlantic and transpacific using 10-30 MHz radios. The terrestrial microwave links (several GHz) have been around for a decade, and HF radio is fairly recent. Starlink will have higher bandwidth, but also higher latency.
wolrah 4y ago
> Interesting. I didn't know that coverage was limited. I assumed satellite == pretty much all of earth. The low orbits that give Starlink its low latency compared to geostationary satellite internet services also mean that each satellite can only see a small part of the earth at any given time. This is why they need so many satellites to provide reliable coverage. Right now each satellite has to communicate directly to a uplink station, so it's only possible to provide coverage to areas where a satellite can simultaneously see the user and the uplink. This is where SpaceX's planned inter-satellite link capability comes in to play, they claim they will be able to use lasers in a free-space optical network (think fiber without the fiber) to relay data directly from satellite to satellite, allowing service more than a single hop from a uplink station. This will also hypothetically allow for direct user to user connections over the satellite network that do not traverse the terrestrial internet, which would be huge for both military and business applications. Lots of words have been written about intercontinental high frequency trading for example. Supposedly every satellite launched in 2022 has the capability but as far as I'm aware it hasn't been openly demonstrated to work yet. Making it work reliably within a single orbital ring is a hard problem and the claimed ability to cross-connect between adjacent rings is an absurdly hard problem. Neither are impossible, but I'll believe it when I see it.
- Phlarp 4y ago
  >I'll believe it when I see it. This whole "yea inter-sat free space fiber links are totally going to happen" charade smacks of the same hype baiting as "full self driving by end of year" nonsense that Elon has been spouting since 2018. The Starlink "team" did an AMA on reddit[0] last year and it was comical how empty the answers were. People asked about the space lasers and the answers were all "yea it's a really hard problem, BTW we're hiring!" which honestly felt like an admission from HR that they're looking for engineers willing/able to cash the checks marketing already wrote. [0] https://www.reddit.com/r/Starlink/comments/jzozv3/every_answer_from_the_starlink_team_ama/ https://www.reddit.com/r/Starlink/comments/jzozv3/every_answ...
  - mlyle 4y ago
    It's not that hard of a problem to do fast free-space optical in space within a single orbital shell. The only thing that makes it hard for SpaceX is the relatively small mass and volume budgets on their satellites to do precision pointing with, and that you'd really want each satellite to be able to do multiple links and that's taking up a lot of space.
stephbu 4y ago
At 550km altitude, each Starlink satellite in low-earth orbit has a visible horizon of only about 700mi, and I suspect usable range that is much smaller, probably low 100’s of miles. To extend range to a ground-station beyond that will probably take multiple peer satellite hops - I suspect that inter-satellite bandwidth is a a precious commodity - and priced as such.
- mlyle 4y ago
  I think you're confusing the horizon of places on the surface of Earth that you can see with the distance to another satellite you can see. 6900km from the center of Earth. Figure you don't want the link to point within 150km (6500km) of Earth, to not pass through much atmosphere and to not see too much atmospheric glow (even with narrow filters, this matters). Effectively you have an isosceles triangle with 6900km on the common side and an altitude of 6500km (tangent to "top of atmosphere" at 150km. sqrt((6900^2 - 6500^2)) * 2 =~ 4600km

It will once they get the laser terminals up and running so the sats can talk to each other

They can't do satellite to satellite yet. Just terminal -> sat -> ground station. Starlink is in low earth orbit, so the visibility any one satellite has is (relatively speaking) pretty limited.

ortusdux 4y ago

The majority of their satellites just bounce the signals back down to a nearby ground station. Their version 1.5 sats, which they started launching about a year ago, include laser links to allow sat->sat communication. Their plan is for the remaining 3/4th of their fleet to have laser links. One interesting side-effect of the laser links is that they can open up connections between stock exchanges and trading houses that are faster than direct fiberoptic lines. Milliseconds count in high frequency trading.

foobiekr 4y ago
Predictability and stability count a lot as well. I think the starlink-as-low-latency-trading-medium is sort of like "blockchain for real estate" - it's not actually a real thing.
- vardump 4y ago
  You can simply use multiple links to send same data. The fastest one wins, so if there's a temporary hickup on one of the links, you still get somewhat bounded latency. When things work fine, you get to reap the latency benefit. So I think it's plausible for intercontinental links.
  - foobiekr 4y ago
    the spot still covers the same ground station much of the time.
pclmulqdq 4y ago
The traders are already using HF radios with lower latency.
- rtkwe 4y ago
  Yeah SpaceX will have a very hard time beating the current routes; they're further from the surface and the intersatellite links won't be travelling in a straight line all the time. The best bet is if they can provide those links across oceans that can't be rigged with microwave towers.
  - pclmulqdq 4y ago
    The HF radios are transatlantic and transpacific using 10-30 MHz radios. The terrestrial microwave links (several GHz) have been around for a decade, and HF radio is fairly recent. Starlink will have higher bandwidth, but also higher latency.

wolrah 4y ago

> Interesting. I didn't know that coverage was limited. I assumed satellite == pretty much all of earth. The low orbits that give Starlink its low latency compared to geostationary satellite internet services also mean that each satellite can only see a small part of the earth at any given time. This is why they need so many satellites to provide reliable coverage. Right now each satellite has to communicate directly to a uplink station, so it's only possible to provide coverage to areas where a satellite can simultaneously see the user and the uplink. This is where SpaceX's planned inter-satellite link capability comes in to play, they claim they will be able to use lasers in a free-space optical network (think fiber without the fiber) to relay data directly from satellite to satellite, allowing service more than a single hop from a uplink station. This will also hypothetically allow for direct user to user connections over the satellite network that do not traverse the terrestrial internet, which would be huge for both military and business applications. Lots of words have been written about intercontinental high frequency trading for example. Supposedly every satellite launched in 2022 has the capability but as far as I'm aware it hasn't been openly demonstrated to work yet. Making it work reliably within a single orbital ring is a hard problem and the claimed ability to cross-connect between adjacent rings is an absurdly hard problem. Neither are impossible, but I'll believe it when I see it.

Phlarp 4y ago
>I'll believe it when I see it. This whole "yea inter-sat free space fiber links are totally going to happen" charade smacks of the same hype baiting as "full self driving by end of year" nonsense that Elon has been spouting since 2018. The Starlink "team" did an AMA on reddit[0] last year and it was comical how empty the answers were. People asked about the space lasers and the answers were all "yea it's a really hard problem, BTW we're hiring!" which honestly felt like an admission from HR that they're looking for engineers willing/able to cash the checks marketing already wrote. [0] https://www.reddit.com/r/Starlink/comments/jzozv3/every_answer_from_the_starlink_team_ama/ https://www.reddit.com/r/Starlink/comments/jzozv3/every_answ...
- mlyle 4y ago
  It's not that hard of a problem to do fast free-space optical in space within a single orbital shell. The only thing that makes it hard for SpaceX is the relatively small mass and volume budgets on their satellites to do precision pointing with, and that you'd really want each satellite to be able to do multiple links and that's taking up a lot of space.

stephbu 4y ago

At 550km altitude, each Starlink satellite in low-earth orbit has a visible horizon of only about 700mi, and I suspect usable range that is much smaller, probably low 100’s of miles. To extend range to a ground-station beyond that will probably take multiple peer satellite hops - I suspect that inter-satellite bandwidth is a a precious commodity - and priced as such.

mlyle 4y ago
I think you're confusing the horizon of places on the surface of Earth that you can see with the distance to another satellite you can see. 6900km from the center of Earth. Figure you don't want the link to point within 150km (6500km) of Earth, to not pass through much atmosphere and to not see too much atmospheric glow (even with narrow filters, this matters). Effectively you have an isosceles triangle with 6900km on the common side and an altitude of 6500km (tangent to "top of atmosphere" at 150km. sqrt((6900^2 - 6500^2)) * 2 =~ 4600km