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> At least V1 of Starlink, there needs to be a ground station visible to the satellite At an altitude of 340 miles a starlink satellite has line of site up to

> At least V1 of Starlink, there needs to be a ground station visible to the satellite At an altitude of 340 miles a starlink satellite has line of site up to 1800 miles so conceivably a ship at sea could be 3600 miles from the nearest land station and still be able to bounce off Starlink. Of course that's ideal conditions, but it wouldn't take too many ground stations to ensure 99% of oceangoing traffic is covered. Of course even with line of site, the antenna may not be oriented in such a way as to cover more than a couple hundred miles of surface even if there is line of site.

shaklee3 6y ago
I think your math is off. What elevation are you using?
- ogre_codes 6y ago
  340 miles. If it's not able to cover more than a couple hundred miles, I don't think it's a line of site issue.
  - shaklee3 6y ago
    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.
    - ogre_codes 6y ago
      Ah, the other definition of elevation. I'm not really sure.
- deleted 6y ago
  [deleted]
Rebelgecko 6y ago
Even though the theoretical line of sight is 1800 miles, I expect that you'll get much less range. The satellites move very quickly— the satellite that's halfway between you and the ground station is very quickly going to be more than 1800 miles away from one of you. Transmitting signals at such oblique angles is also a lot harder. Part of it is just typical signal strength los due to r^2 law. But if you're transmitting thru that much atmosphere, you're going to experience a lot more interference from things like rain fade.

shaklee3 6y ago

I think your math is off. What elevation are you using?

ogre_codes 6y ago
340 miles. If it's not able to cover more than a couple hundred miles, I don't think it's a line of site issue.
- shaklee3 6y ago
  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.
  - ogre_codes 6y ago
    Ah, the other definition of elevation. I'm not really sure.
deleted 6y ago
[deleted]

Rebelgecko 6y ago

Even though the theoretical line of sight is 1800 miles, I expect that you'll get much less range. The satellites move very quickly— the satellite that's halfway between you and the ground station is very quickly going to be more than 1800 miles away from one of you. Transmitting signals at such oblique angles is also a lot harder. Part of it is just typical signal strength los due to r^2 law. But if you're transmitting thru that much atmosphere, you're going to experience a lot more interference from things like rain fade.