4 ms·

Can someone explain the physical layer aspects of starlink? Is the spectrum same as mobile data spectrum or does it work with different part of spectrum. If it

Can someone explain the physical layer aspects of starlink? Is the spectrum same as mobile data spectrum or does it work with different part of spectrum. If it is different part, do we need specific hardware to receive and transmit? Are there any interference/loses issues that might popup when scaled? What is stopping spaceX to provide internet outside US?

lmm 6y ago
> Can someone explain the physical layer aspects of starlink? Is the spectrum same as mobile data spectrum or does it work with different part of spectrum. If it is different part, do we need specific hardware to receive and transmit? Almost certainly has its own slice of spectrum. You need a pizza-box sized antenna set up, so it's not quite person-portable yet, but not too bad for installing on a vehicle. > Are there any interference/loses issues that might popup when scaled? Each satellite only has so much bandwidth. So the more people using it in the same area, the worse it's going to get. In theory they'll add more satellites as needed, but it's never going to be much good for towns/cities. > What is stopping spaceX to provide internet outside US? Ground stations and regulations. Once they have satellite-satellite communications running the ground stations become less of an issue (though there's a latency penalty if your signal has to go a long way round the satellites before getting to the ground).
- MayeulC 6y ago
  Well, I would add that both satellite and ground receiver have phased arrays antennae. These allow emitting multiple focused beams simultaneously. Since the angular resolution of these beams is limited, they each cover a fixed ground area (let's say 20km across). If more than one customer sits in that area, they will have to share airtime with the others. Now, it's probably easier for the satellite to perform (time-division or other) multiplexing, since it knows how much data each node is going to receive. I guess it's a lot more involved when it comes to sharing upload bandwidth with another client you can't see. Anyway, this makes it easy to scale in rural areas, and pretty much a no-go for cities. Now, a question of my own: do SpaceX satellites already have HW for sat-to-sat communication?

lmm 6y ago

> Can someone explain the physical layer aspects of starlink? Is the spectrum same as mobile data spectrum or does it work with different part of spectrum. If it is different part, do we need specific hardware to receive and transmit? Almost certainly has its own slice of spectrum. You need a pizza-box sized antenna set up, so it's not quite person-portable yet, but not too bad for installing on a vehicle. > Are there any interference/loses issues that might popup when scaled? Each satellite only has so much bandwidth. So the more people using it in the same area, the worse it's going to get. In theory they'll add more satellites as needed, but it's never going to be much good for towns/cities. > What is stopping spaceX to provide internet outside US? Ground stations and regulations. Once they have satellite-satellite communications running the ground stations become less of an issue (though there's a latency penalty if your signal has to go a long way round the satellites before getting to the ground).

MayeulC 6y ago
Well, I would add that both satellite and ground receiver have phased arrays antennae. These allow emitting multiple focused beams simultaneously. Since the angular resolution of these beams is limited, they each cover a fixed ground area (let's say 20km across). If more than one customer sits in that area, they will have to share airtime with the others. Now, it's probably easier for the satellite to perform (time-division or other) multiplexing, since it knows how much data each node is going to receive. I guess it's a lot more involved when it comes to sharing upload bandwidth with another client you can't see. Anyway, this makes it easy to scale in rural areas, and pretty much a no-go for cities. Now, a question of my own: do SpaceX satellites already have HW for sat-to-sat communication?