7 ms·

He's halving altitude to 550 km, in ideal cases bringing latency to 15 ms. Some satellites will be even lower, 350 km, for populated areas. https://arstechnica

He's halving altitude to 550 km, in ideal cases bringing latency to 15 ms. Some satellites will be even lower, 350 km, for populated areas. https://arstechnica.com/tech-policy/2019/04/spacex-changes-broadband-satellite-plan-to-limit-debris-and-lower-latency/ https://arstechnica.com/tech-policy/2019/04/spacex-changes-b...

jayess 8y ago
I presume that's just one direction?
RHSeeger 8y ago
Is it 15ms to the satellite? If so, that's like 30ms to land, which would negatively impact gaming if it still needs to travel from where it lands to the end goal (via normal pathing?)
- slenk 8y ago
  30ms is a good ping for games... edit - yeah I forgot about the endpoint then to the game servers data center
  - jalgos_eminator 8y ago
    The 30ms figure is just the earth->satellite->earth part though. It still has to go through terrestrial wires to the server, and then be processed, and back through wires to the transmitter.
    - imtringued 8y ago
      Datacenters make deals with network providers. Why should it be any different with Starlink?
  - earenndil 8y ago
    That's not 30ms ping, that's add 30ms ping.
    - slenk 8y ago
      Not always I don't think. Maybe from me to a geographic location 400 miles away, yes. But what about 4k miles away, like coast to coast? That would probably depend on how many satellites it has to bounce through and how far it has to travel terrestrial, but I would think there is a geographic distance where that 30ms is faster.
      - anticensor 8y ago
        Up to three. After one bounce, it can be redirected into a geostationary or a polar satellite where the final bouncer would reach its LEO peer again.
    - awj 8y ago
      That statement assumes no transmission latency on your current setup. Kinda doubt that's the case.
  - dragonwriter 8y ago
    30ms would be you and the game server both on Starlink, on the same satellite. Otherwise, you have to add that to the latency between the ground station and the target server.
    - vel0city 8y ago
      IIRC, the plan with Starlink is to have many stations that are supposedly easy to operate in many large-ish datacenters in major areas as opposed to systems like Iridium which have few, complex downlink stations in comparison.
- frickinLasers 8y ago
  A 550km trip at the speed of light should take just under 2ms. It looks like they've accounted for the other stuff.
- senectus1 8y ago
  I mean, I'm a gamer but really... its pretty low on the list of important reasons to support such a project.
- amirhirsch 8y ago
  1000 km / speed of light = 3.34 ms. Suppose you want to ping a server next door to you and your ISP is a satellite 1000 km away. The distance your signal travels is 1000km from client to satellite, 1000 km from satellite to server, 1000km from server to satellite and 1000km satellite back to client. 4000 km at the speed of light is 13.34ms (the transceiving latency is probably negligible in comparison, though I'm not 100% sure about the DSP requirements for this sort of system) If the target server is far away and the signal goes 7000 km from satellite to satellite in space before coming back down, then your signal it will need at least 46.7ms more in space for a 14km round trip in space, which results in a minimum possible ping of 60ms to ping a server 7000 km away. Fiber-optics are 30% slower than radio links, so this 60ms minimum is 10% lower latency than the best fiber-optics can do: (7000 km / .7 speed-of-light) = 66ms If the distance to your server is 2.333x the distance to your satellite you will have lower latency with radio than fiber optics. Bringing the altitude of the satellites down will make a big difference, but you also need a lot more of them in a constellation to have low average distances.
  - RHSeeger 8y ago
    But for something more realistic for gaming, a player in Boston hitting a server in NY. The fiber message travels something like 200 miles, while the satellite message travels 2,200 miles.
    - amirhirsch 8y ago
      Boston to New York is 215mi or a 430 mile round trip. At 200 miles up where they intend to put the satellites orbiting over major cities, it's going to be about 1000 mile round trip. I thought that the US servers for most games are in the middle of the country to get the best average ping for a cross-country audience. Blizzard is like Chicago and Texas.
      - penagwin 8y ago
        Not usually. In my experience, they usually follow the typical popular datacenter areas e.g. East Coast/West Coast. I've mostly only seen really popular games offer Central locations like Dallas/Chicago. But it's getting a lot better now that vultr (COD uses them) and other VPS providers get more and more locations.
- deleted 8y ago
  [deleted]
- AngryData 8y ago
  Rural customers are use to 100+ ms response time. Even getting 60 ms response time would be a major improvement for many customers.
nradov 8y ago
Has anyone published the expected lifetime of those satellites? At the lower end of that altitude range the drag is going to be pretty severe.

jayess 8y ago

I presume that's just one direction?

RHSeeger 8y ago

Is it 15ms to the satellite? If so, that's like 30ms to land, which would negatively impact gaming if it still needs to travel from where it lands to the end goal (via normal pathing?)

slenk 8y ago
30ms is a good ping for games... edit - yeah I forgot about the endpoint then to the game servers data center
- jalgos_eminator 8y ago
  The 30ms figure is just the earth->satellite->earth part though. It still has to go through terrestrial wires to the server, and then be processed, and back through wires to the transmitter.
  - imtringued 8y ago
    Datacenters make deals with network providers. Why should it be any different with Starlink?
- earenndil 8y ago
  That's not 30ms ping, that's add 30ms ping.
  - slenk 8y ago
    Not always I don't think. Maybe from me to a geographic location 400 miles away, yes. But what about 4k miles away, like coast to coast? That would probably depend on how many satellites it has to bounce through and how far it has to travel terrestrial, but I would think there is a geographic distance where that 30ms is faster.
    - anticensor 8y ago
      Up to three. After one bounce, it can be redirected into a geostationary or a polar satellite where the final bouncer would reach its LEO peer again.
  - awj 8y ago
    That statement assumes no transmission latency on your current setup. Kinda doubt that's the case.
- dragonwriter 8y ago
  30ms would be you and the game server both on Starlink, on the same satellite. Otherwise, you have to add that to the latency between the ground station and the target server.
  - vel0city 8y ago
    IIRC, the plan with Starlink is to have many stations that are supposedly easy to operate in many large-ish datacenters in major areas as opposed to systems like Iridium which have few, complex downlink stations in comparison.
frickinLasers 8y ago
A 550km trip at the speed of light should take just under 2ms. It looks like they've accounted for the other stuff.
senectus1 8y ago
I mean, I'm a gamer but really... its pretty low on the list of important reasons to support such a project.
amirhirsch 8y ago
1000 km / speed of light = 3.34 ms. Suppose you want to ping a server next door to you and your ISP is a satellite 1000 km away. The distance your signal travels is 1000km from client to satellite, 1000 km from satellite to server, 1000km from server to satellite and 1000km satellite back to client. 4000 km at the speed of light is 13.34ms (the transceiving latency is probably negligible in comparison, though I'm not 100% sure about the DSP requirements for this sort of system) If the target server is far away and the signal goes 7000 km from satellite to satellite in space before coming back down, then your signal it will need at least 46.7ms more in space for a 14km round trip in space, which results in a minimum possible ping of 60ms to ping a server 7000 km away. Fiber-optics are 30% slower than radio links, so this 60ms minimum is 10% lower latency than the best fiber-optics can do: (7000 km / .7 speed-of-light) = 66ms If the distance to your server is 2.333x the distance to your satellite you will have lower latency with radio than fiber optics. Bringing the altitude of the satellites down will make a big difference, but you also need a lot more of them in a constellation to have low average distances.
- RHSeeger 8y ago
  But for something more realistic for gaming, a player in Boston hitting a server in NY. The fiber message travels something like 200 miles, while the satellite message travels 2,200 miles.
  - amirhirsch 8y ago
    Boston to New York is 215mi or a 430 mile round trip. At 200 miles up where they intend to put the satellites orbiting over major cities, it's going to be about 1000 mile round trip. I thought that the US servers for most games are in the middle of the country to get the best average ping for a cross-country audience. Blizzard is like Chicago and Texas.
    - penagwin 8y ago
      Not usually. In my experience, they usually follow the typical popular datacenter areas e.g. East Coast/West Coast. I've mostly only seen really popular games offer Central locations like Dallas/Chicago. But it's getting a lot better now that vultr (COD uses them) and other VPS providers get more and more locations.
deleted 8y ago
[deleted]
AngryData 8y ago
Rural customers are use to 100+ ms response time. Even getting 60 ms response time would be a major improvement for many customers.

nradov 8y ago

Has anyone published the expected lifetime of those satellites? At the lower end of that altitude range the drag is going to be pretty severe.