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> it sounds like Musk wants to shift to being a satellite backbone, Musk and his network team are not that dumb. They know about the Shannon limit in rf microw

> it sounds like Musk wants to shift to being a satellite backbone, Musk and his network team are not that dumb. They know about the Shannon limit in rf microwave and millimeter wave and the multi terahertz channel width capacity of basic 9/125 SM fiber. Anything RF based has incredibly tiny capacity compared to modern 100/200/400GbE 40/80 channel dwdm systems. The capacity of two strands of fiber on a long haul path is incredible. Internet backbone links carry far too much traffic to handle through even the most optimistic starlink sat to sat laser links. I 100% concur with you on the foolishness of the cable. It should be some kind of ip68 rated twist lock Ethernet connector.

kortilla 4y ago
Why do you think 100gbps+ is not feasible for sat to sat lasers? The vacuum of space is a better environment than 500km of glass with a bunch of inline repeaters.
- walrus01 4y ago
  Because a few discrete OOK lasers in a single frequency aiming at another moving target, while they will have a lot of capacity compared to an rf link, will have a minuscule amount of capacity in Gbps compared to a whole DWDM based, coherent 100GbE+ optical transport system operating on singlemode fiber. Like, literally, twenty or thirty individual full duplex 400GbE circuits in two strands of fiber, if you have enough money to throw at the problem. The only way you could approach matching the same capacity on a sat to sat link would be if you had a massive array of 30-40 separate laser tx and corresponding massive array of 30-40 rx receptors on the other side. It's easier to understand if you've seen a DWDM mux and demux in person in a telecom facility. I'd like to be proven wrong if somebody can do multi Tbps of capacity on a sat to sat laser link, that would be awesome, but the challenges are very high.
  - ben_w 4y ago
    > The only way you could approach matching the same capacity on a sat to sat link would be if you had a massive array of 30-40 separate laser tx and corresponding massive array of 30-40 rx receptors on the other side. This does sound like the sort of thing Musk would try, especially post-Starship, if the rest of the setup was physically possible.
    - walrus01 4y ago
      One of the other problems is that the ultimate last hop for data would still have to be an rf link satellite to earth station through atmosphere, where lasers don't work well at all (there's a rain and junk in the air reason the telecom industry has given up on free space optics lasers for 1-2km, 1 to 20Gbps data links roof to roof and uses millimeter wave fdd radios instead)
  - panick21_ 4y ago
    I think it might be more about latency then pure capacity.
  - kortilla 4y ago
    > Because a few discrete OOK lasers in a single frequency aiming at another moving target Two sats in the same shell are not moving relative to each other.
    - walrus01 4y ago
      Two satellites from the same launch, in the same orbital inclination, following each other in a conga line of starlink satellites are still slightly moving relative to each other, considering the narrow beam width of a laser shot at distances of 50 to 80 km or more between satellites.

kortilla 4y ago

Why do you think 100gbps+ is not feasible for sat to sat lasers? The vacuum of space is a better environment than 500km of glass with a bunch of inline repeaters.

walrus01 4y ago
Because a few discrete OOK lasers in a single frequency aiming at another moving target, while they will have a lot of capacity compared to an rf link, will have a minuscule amount of capacity in Gbps compared to a whole DWDM based, coherent 100GbE+ optical transport system operating on singlemode fiber. Like, literally, twenty or thirty individual full duplex 400GbE circuits in two strands of fiber, if you have enough money to throw at the problem. The only way you could approach matching the same capacity on a sat to sat link would be if you had a massive array of 30-40 separate laser tx and corresponding massive array of 30-40 rx receptors on the other side. It's easier to understand if you've seen a DWDM mux and demux in person in a telecom facility. I'd like to be proven wrong if somebody can do multi Tbps of capacity on a sat to sat laser link, that would be awesome, but the challenges are very high.
- ben_w 4y ago
  > The only way you could approach matching the same capacity on a sat to sat link would be if you had a massive array of 30-40 separate laser tx and corresponding massive array of 30-40 rx receptors on the other side. This does sound like the sort of thing Musk would try, especially post-Starship, if the rest of the setup was physically possible.
  - walrus01 4y ago
    One of the other problems is that the ultimate last hop for data would still have to be an rf link satellite to earth station through atmosphere, where lasers don't work well at all (there's a rain and junk in the air reason the telecom industry has given up on free space optics lasers for 1-2km, 1 to 20Gbps data links roof to roof and uses millimeter wave fdd radios instead)
- panick21_ 4y ago
  I think it might be more about latency then pure capacity.
- kortilla 4y ago
  > Because a few discrete OOK lasers in a single frequency aiming at another moving target Two sats in the same shell are not moving relative to each other.
  - walrus01 4y ago
    Two satellites from the same launch, in the same orbital inclination, following each other in a conga line of starlink satellites are still slightly moving relative to each other, considering the narrow beam width of a laser shot at distances of 50 to 80 km or more between satellites.