So no inter-satellite links on the first version of the satellites -- doing the same as OneWeb.
Quote from: RedLineTrain on 11/08/2018 11:38 pmSo no inter-satellite links on the first version of the satellites -- doing the same as OneWeb.This is unclear.They say they may swap out components, and there is a maximum of 4 mirrors to do LASER comms.Going to 5 for the later version does not mean that this version is not doing inter-satellite LASER comms, or most of the initial fleet will have none.It clearly means the mix has changed.And of course, inter-satellite radio is still possible.
I agree that inter-satellite radio is possible. Good point. Are Microsat A & B using radio links? Regarding the LASERs, read on and it becomes clear that not all three components are going to be on the first version. The reaction wheels and thruster are going to be there, meaning that the silicon carbide (LASER) components are not.
Quote from: RedLineTrain on 11/09/2018 12:09 amI agree that inter-satellite radio is possible. Good point. Are Microsat A & B using radio links? Regarding the LASERs, read on and it becomes clear that not all three components are going to be on the first version. The reaction wheels and thruster are going to be there, meaning that the silicon carbide (LASER) components are not.If they had changed from laser ISL then the frequencies would have been listed (and it would be a major revision to their application).
Where does it say or imply they’re dropping laser ISL?
Edit: Tintin A and B have optical links. Hmmm...https://apps.fcc.gov/els/GetAtt.html?id=185534&x=.
If the laser links aren’t there, Mark Handley’s analysis doesn’t apply anymore, at least for the early version. If they are there, cutting the altitude in half would drop latency even further below the best fiber can even theoretically do and double down on the high frequency trading/financial data biz as a license to print money. https://forum.nasaspaceflight.com/index.php?topic=36552.2340
Quote from: Ludus on 11/10/2018 05:23 amIf the laser links aren’t there, Mark Handley’s analysis doesn’t apply anymore, at least for the early version. If they are there, cutting the altitude in half would drop latency even further below the best fiber can even theoretically do and double down on the high frequency trading/financial data biz as a license to print money. https://forum.nasaspaceflight.com/index.php?topic=36552.2340'theoretical' is not meaningful if it assumes that the limit is the speed of light in glass, because 'air-core' fibers exist, which have nearly the same transmission speed as in vacuum.
Quote from: speedevil on 11/10/2018 02:38 pmQuote from: Ludus on 11/10/2018 05:23 amIf the laser links aren’t there, Mark Handley’s analysis doesn’t apply anymore, at least for the early version. If they are there, cutting the altitude in half would drop latency even further below the best fiber can even theoretically do and double down on the high frequency trading/financial data biz as a license to print money. https://forum.nasaspaceflight.com/index.php?topic=36552.2340'theoretical' is not meaningful if it assumes that the limit is the speed of light in glass, because 'air-core' fibers exist, which have nearly the same transmission speed as in vacuum.I think Handley is just considering routes for fiber, not future variations in the basic technology. Theoretical in this case just meaning that even with a direct optimal “great circle” connection, though significantly faster than current fiber routes, wouldn’t be as fast as quite a few potential paths on Starlink. He didn’t consider advances in fiber or the later lower orbit and denser mesh phases of Starlink.
“Advances in fiber” won’t affect Handley’s analysis WRT great circle minimums, because he is only considering the physical speed of light in glass vs speed of links in air/vacuum.Altitude and circuit latency on the satellites will have greater impact than any future improvements in fiber.