5 ms·

Not the altitude, but the elevation. What is the angle from the user terminal?

Dylan16807 6y ago
It just has to be above the horizon, because this is the middle of the ocean. When I put 550km into a horizon calculator I get a distance of 2700km. Edit: Okay, I want an explanation for the downvotes. If you're upset that I didn't say "the user terminal is horizontal at max range", I thought it was clear from context.
- shaklee3 6y ago
  I didn't downvote you, but the size of the beam is heavily dictated by the elevation they're willing to work with, and the wider the elevation, the more expensive the antenna. So give that they need to decrease the size of the beam to keep antenna cost down, it's highly likely that the beam size is much, much smaller than what you cited there. Just take a look to see how many handoffs there are over CONUS alone: https://www.youtube.com/watch?v=m05abdGSOxY https://www.youtube.com/watch?v=m05abdGSOxY
  - Dylan16807 6y ago
    We're talking about the user terminal, right? A ship can easily have a more expensive antenna array. Maybe even with a motor, or with three tilted in different directions. > Just take a look to see how many handoffs there are over CONUS alone That's just a simulation picking angles he thought looked good, in an area where there are plenty of options. It doesn't tell you anything about the limits of beam size, especially when there is no other sat in range.
    - shaklee3 6y ago
      Sure, ships can have more expensive antennas. But you need a lot of those ships out there and the antennas are extremely expensive. I'm not sure what you are arguing about the simulation. Are you saying it's inaccurate and there's a better one?
      - Dylan16807 6y ago
        > Sure, ships can have more expensive antennas. But you need a lot of those ships out there and the antennas are extremely expensive. We're talking about receiving internet on ships, right? You need one per ship that wants internet. And it doesn't have to be 'extremely' expensive, it could be a moderate multiple of the normal user terminal. In case you forgot the context, this is not a conversation about using relays. This is a conversation about how far offshore you can go in a single bounce. > I'm not sure what you are arguing about the simulation. Are you saying it's inaccurate and there's a better one? It's perfectly fine, but the goal of that simulation is to show a way of doing long distance high speed relays. The goal is not to show you maximum range if you don't relay.
        shaklee3 6y ago
        I'm talking about ships used for relay. Ships used for just internet over the water won't be possible if there are no gateways (other ships with relays) over the water. Those terminals do have to be expensive, just like the gateway ones, because the antenna performance is much higher than the user terminal's, and the radome is very large (see other pictures from reddit on here). For the non-relay case, we've already established that due to beam size you can't get very far off shore before it won't work. The goal of the simulation was also to show beam size. If the beam sizes are arbitrarily large then obviously the simulation would have shown a single hop.
        Dylan16807 6y ago
        > I'm talking about ships used for relay. Ships used for just internet over the water won't be possible if there are no gateways (other ships with relays) over the water. I figured that out, but that's not really what the conversation was about. If you add those gateways then you don't have the range problems, and this was a conversation about range problems. > Those terminals do have to be expensive, just like the gateway ones, because the antenna performance is much higher than the user terminal's, and the radome is very large (see other pictures from reddit on here). The video you linked talks about using normal user terminals as relays. A couple of those won't be full bandwidth, but your mid-ocean service wouldn't need to be full bandwidth. If you're actually making a dedicated relay ship you'd probably want a full radome link, but only if it's cheaper than the ship you're putting it on. The limiting factor is the cost of the ships. > The goal of the simulation was also to show beam size. I strongly disagree. Beam size is modeled in a very simple way, because it's not the goal of the simulation. The goal is to show how links work in different ways, using normal-scope full-bandwidth service beams. I strongly doubt that an almost-idle sat is unable to aim even a few degrees wider if they wanted to. But the person making that sim would have no way to model that, and it's not really worth it to get an extra fraction of a millisecond. Better to make the simulation based on confirmed capability. But for ships at sea it's not a fraction of a millisecond, it's the difference between connectivity and no connectivity. If ships at sea were starlink's primary customers then I bet they could and would get better range even with zero hardware changes.
ogre_codes 6y ago
Ah, the other definition of elevation. I'm not really sure.

It just has to be above the horizon, because this is the middle of the ocean. When I put 550km into a horizon calculator I get a distance of 2700km. Edit: Okay, I want an explanation for the downvotes. If you're upset that I didn't say "the user terminal is horizontal at max range", I thought it was clear from context.

shaklee3 6y ago
I didn't downvote you, but the size of the beam is heavily dictated by the elevation they're willing to work with, and the wider the elevation, the more expensive the antenna. So give that they need to decrease the size of the beam to keep antenna cost down, it's highly likely that the beam size is much, much smaller than what you cited there. Just take a look to see how many handoffs there are over CONUS alone: https://www.youtube.com/watch?v=m05abdGSOxY https://www.youtube.com/watch?v=m05abdGSOxY
- Dylan16807 6y ago
  We're talking about the user terminal, right? A ship can easily have a more expensive antenna array. Maybe even with a motor, or with three tilted in different directions. > Just take a look to see how many handoffs there are over CONUS alone That's just a simulation picking angles he thought looked good, in an area where there are plenty of options. It doesn't tell you anything about the limits of beam size, especially when there is no other sat in range.
  - shaklee3 6y ago
    Sure, ships can have more expensive antennas. But you need a lot of those ships out there and the antennas are extremely expensive. I'm not sure what you are arguing about the simulation. Are you saying it's inaccurate and there's a better one?
    - Dylan16807 6y ago
      > Sure, ships can have more expensive antennas. But you need a lot of those ships out there and the antennas are extremely expensive. We're talking about receiving internet on ships, right? You need one per ship that wants internet. And it doesn't have to be 'extremely' expensive, it could be a moderate multiple of the normal user terminal. In case you forgot the context, this is not a conversation about using relays. This is a conversation about how far offshore you can go in a single bounce. > I'm not sure what you are arguing about the simulation. Are you saying it's inaccurate and there's a better one? It's perfectly fine, but the goal of that simulation is to show a way of doing long distance high speed relays. The goal is not to show you maximum range if you don't relay.
      - shaklee3 6y ago
        I'm talking about ships used for relay. Ships used for just internet over the water won't be possible if there are no gateways (other ships with relays) over the water. Those terminals do have to be expensive, just like the gateway ones, because the antenna performance is much higher than the user terminal's, and the radome is very large (see other pictures from reddit on here). For the non-relay case, we've already established that due to beam size you can't get very far off shore before it won't work. The goal of the simulation was also to show beam size. If the beam sizes are arbitrarily large then obviously the simulation would have shown a single hop.
        Dylan16807 6y ago
        > I'm talking about ships used for relay. Ships used for just internet over the water won't be possible if there are no gateways (other ships with relays) over the water. I figured that out, but that's not really what the conversation was about. If you add those gateways then you don't have the range problems, and this was a conversation about range problems. > Those terminals do have to be expensive, just like the gateway ones, because the antenna performance is much higher than the user terminal's, and the radome is very large (see other pictures from reddit on here). The video you linked talks about using normal user terminals as relays. A couple of those won't be full bandwidth, but your mid-ocean service wouldn't need to be full bandwidth. If you're actually making a dedicated relay ship you'd probably want a full radome link, but only if it's cheaper than the ship you're putting it on. The limiting factor is the cost of the ships. > The goal of the simulation was also to show beam size. I strongly disagree. Beam size is modeled in a very simple way, because it's not the goal of the simulation. The goal is to show how links work in different ways, using normal-scope full-bandwidth service beams. I strongly doubt that an almost-idle sat is unable to aim even a few degrees wider if they wanted to. But the person making that sim would have no way to model that, and it's not really worth it to get an extra fraction of a millisecond. Better to make the simulation based on confirmed capability. But for ships at sea it's not a fraction of a millisecond, it's the difference between connectivity and no connectivity. If ships at sea were starlink's primary customers then I bet they could and would get better range even with zero hardware changes.

ogre_codes 6y ago

Ah, the other definition of elevation. I'm not really sure.