3 ms·

I was actually wrong. The spot size is 1.5 degrees, or ~10km. The source is the original Starlink FCC filing: https://cdn3.vox-cdn.com/uploads/chorus_asset/fil

I was actually wrong. The spot size is 1.5 degrees, or ~10km. The source is the original Starlink FCC filing: https://cdn3.vox-cdn.com/uploads/chorus_asset/file/8174403/SpaceX_Application_-.0.pdf https://cdn3.vox-cdn.com/uploads/chorus_asset/file/8174403/S... But the point remains: The Starlink satellites do not just radiate omnidirectionally. Nor could they; the system is intended to eventually serve a meaningful fraction of the entire population on earth. This is not possible on non-steered RF. The only reason their plan has any sense is that every transmitter and receiver is directional, allowing efficient SDMA, where the same frequency can be used by multiple people simultaneously to communicate withe the same satellite, because the satellite can discriminate between their signals by the direction from which they were received. Because of this, in order for Starlink to be able to communicate with you, it has to have a pretty good idea of where you are.

mrtksn 7y ago
Can you quote the information? I couldn't find this in the document. I am sceptical that they can have that narrow beams and track the users(as the sattelite passes over them) from non-geostationary low earth orbit satellites. I would like to investigate this.
- Tuna-Fish 7y ago
  From A2: overall description: > Advanced phased array beam-forming and digital processing technologies within the satellite payload give the system the ability to make highly efficient use of Ku- and Ka-band spectrum resources and the flexibility to share that spectrum with other licensed users. User terminals operating with the SpaceX System will use similar phased array technologies to allow for highly directive, steered antenna beams that track the system’s low-Earth orbit satellites. Gateway earth stations also apply advanced phased array technologies to generate high-gain steered beams to communicate with multiple NGSO satellites from a single gateway site. Details of the downlink beams is found at A3: > All Ku-band downlink spot beams on each SpaceX satellite are independently steerable over the full field of view of the Earth. Just read the entire A3.1 for more details.

mrtksn 7y ago

Can you quote the information? I couldn't find this in the document. I am sceptical that they can have that narrow beams and track the users(as the sattelite passes over them) from non-geostationary low earth orbit satellites. I would like to investigate this.

Tuna-Fish 7y ago
From A2: overall description: > Advanced phased array beam-forming and digital processing technologies within the satellite payload give the system the ability to make highly efficient use of Ku- and Ka-band spectrum resources and the flexibility to share that spectrum with other licensed users. User terminals operating with the SpaceX System will use similar phased array technologies to allow for highly directive, steered antenna beams that track the system’s low-Earth orbit satellites. Gateway earth stations also apply advanced phased array technologies to generate high-gain steered beams to communicate with multiple NGSO satellites from a single gateway site. Details of the downlink beams is found at A3: > All Ku-band downlink spot beams on each SpaceX satellite are independently steerable over the full field of view of the Earth. Just read the entire A3.1 for more details.