5 ms·

degrees from horizon?

gpm 6y ago
Imagine you're standing in a flat field, facing the satellite. Degrees from the horizon is how far you would have to bend your neck to be looking straight at the satellite. FCC filings suggest 25 is the absolute minimum for service, the final constellation is likely to use somewhere in 40-60 as the actual limit. I've received this question a few times now, anyone have a better name? Or maybe I should just add a ? button with a diagram?
- cartooncutout 6y ago
  thanks for the elaboration.. maybe just add this explanation as a tooltip on hover or something similar?
- tialaramex 6y ago
  I'm guessing based on my own experience that it's obvious if you understand why that would matter. So the diagram may be the best option, maybe with a Wikipedia link if there's an appropriate one?
- toomuchtodo 6y ago
  You might link to the graphic on this page as a quick reference. Should be public domain as a government work if you want to host it. https://spotthestation.nasa.gov/message_example.cfm https://spotthestation.nasa.gov/message_example.cfm https://spotthestation.nasa.gov/images/astro_horizon.png https://spotthestation.nasa.gov/images/astro_horizon.png
- samcheng 6y ago
  A common term is zenith angle, although that's the complement of the angle you're describing.
deleted 6y ago
[deleted]
tialaramex 6y ago
The planet is definitely in the way of radio transmissions between you and a satellite "below the horizon" and even if it could pass through the planet that's a long way. On the other hand a satellite in a boring orbit that's directly above you is 90° from the horizon with no obstacles and as close as it'll ever be so your reception ought to be good. An optimist might believe Starlink will work at 10° above the horizon. A pessimist might doubt anybody will get it working below 80° (ie almost directly overhead). The reality is likely to be in between and this UI lets you see the effect.
- JshWright 6y ago
  "Optimism" and "pessimism" don't really apply here. While SpaceX hasn't publicly committed to what the "operational" value will be, it's likely they had a very good idea before they flew any hardware.
  - gpm 6y ago
    SpaceX is still developing the user terminal, there might be a bit of optimism/pessimism in the degree to which they'll be able to make the user terminal target different angles (without bloating costs), though the person you're replying to definitely exaggerated the extent.

gpm 6y ago

Imagine you're standing in a flat field, facing the satellite. Degrees from the horizon is how far you would have to bend your neck to be looking straight at the satellite. FCC filings suggest 25 is the absolute minimum for service, the final constellation is likely to use somewhere in 40-60 as the actual limit. I've received this question a few times now, anyone have a better name? Or maybe I should just add a ? button with a diagram?

cartooncutout 6y ago
thanks for the elaboration.. maybe just add this explanation as a tooltip on hover or something similar?
tialaramex 6y ago
I'm guessing based on my own experience that it's obvious if you understand why that would matter. So the diagram may be the best option, maybe with a Wikipedia link if there's an appropriate one?
toomuchtodo 6y ago
You might link to the graphic on this page as a quick reference. Should be public domain as a government work if you want to host it. https://spotthestation.nasa.gov/message_example.cfm https://spotthestation.nasa.gov/message_example.cfm https://spotthestation.nasa.gov/images/astro_horizon.png https://spotthestation.nasa.gov/images/astro_horizon.png
samcheng 6y ago
A common term is zenith angle, although that's the complement of the angle you're describing.

deleted 6y ago

[deleted]

tialaramex 6y ago

The planet is definitely in the way of radio transmissions between you and a satellite "below the horizon" and even if it could pass through the planet that's a long way. On the other hand a satellite in a boring orbit that's directly above you is 90° from the horizon with no obstacles and as close as it'll ever be so your reception ought to be good. An optimist might believe Starlink will work at 10° above the horizon. A pessimist might doubt anybody will get it working below 80° (ie almost directly overhead). The reality is likely to be in between and this UI lets you see the effect.

JshWright 6y ago
"Optimism" and "pessimism" don't really apply here. While SpaceX hasn't publicly committed to what the "operational" value will be, it's likely they had a very good idea before they flew any hardware.
- gpm 6y ago
  SpaceX is still developing the user terminal, there might be a bit of optimism/pessimism in the degree to which they'll be able to make the user terminal target different angles (without bloating costs), though the person you're replying to definitely exaggerated the extent.