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Lasers enable satellite internet backbone, might remove need for deep-sea cables

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Re: Lasers enable satellite internet backbone, might remove need for deep-sea cables

#61
post #44

Earlier quoted context omitted.

Congrats, you've reinvented microwave lines, widely deployed in exactly this manner.

The big difference between open air laser and microwave links is that one of them doesn't require licensed spectrum. The costs of doing it will be much lower.

Microwave is also slow compared to this.

Re: Lasers enable satellite internet backbone, might remove need for deep-sea cables

#63

Earlier quoted context omitted.

How hard can it be

To be clear, Starlink is already doing this. Their satellites have laser links that connect them to each other.

They’ve launched satellites with laser links, but I don’t think they’ve got the satellite-to-satellite links active yet. https://www.starlink.com/technology says “testing” for that feature.

Re: Lasers enable satellite internet backbone, might remove need for deep-sea cables

#65
This sure sounds useful, but "might remove need for deep-sea cables" is quite silly.

Anything they do to cram bandwidth into their laser link can reasonably also be applied to fiber optical cables. Except the fiber optical cables come in bundles of 12 to 144 with absolutely no separation issues. Replicating that over open space (air or vacuum), if reasonably possible at all, will chug significant amounts of power in signal processing at the receive end.

There are major benefits to free-space optics -

- quicker to build

- lower latency

- in some cases, large coverage

But deep-sea cables compete on bandwidth, and that's not something free-space optics can beat them on. Why diminish this research achievement by conflating it with that? :(

Re: Lasers enable satellite internet backbone, might remove need for deep-sea cables

#67
post #60

Earlier quoted context omitted.

The big difference between open air laser and microwave links is that one of them doesn't require licensed spectrum. The costs of doing it will be much lower.

Fair! And the existing MW re-translator towers can be upgraded / reused this way. Lasers have a downside though: optical and near IR light is much more readily absorbed by water vapor than microwaves. I wonder if a maser would be an acceptable solution, if cheaper versions of it existed.

1550nm water is super transparent.

Re: Lasers enable satellite internet backbone, might remove need for deep-sea cables

#68

Earlier quoted context omitted.

To be clear, Starlink is already doing this. Their satellites have laser links that connect them to each other.

They’ve launched satellites with laser links, but I don’t think they’ve got the satellite-to-satellite links active yet. https://www.starlink.com/technology says “testing” for that feature.

The website is out of date.

They are already providing service over open ocean out of reach of one hop to base station.

Re: Lasers enable satellite internet backbone, might remove need for deep-sea cables

#69
post #33

The key thing here is it allows for very high bandwidth to go almost anywhere on earth, not just spots where it's easy to land a cable. Starlink's already demonstrated how great that is for consumer bandwidth (50Mbps); a multi-gigabit link terminated at a satellite is fantastic. The part that impresses me most is they're talking about LEO satellites. Those move fast! Starlink does this with a very impressive phased a…

> how great that is for consumer bandwidth (50Mbps) 50 Mbps is great consumer bandwidth where?

Sadly, in most of the rural US. My other options are 12Mbps fixed wireless, 1-100Mbps cellular, or 3Mbps DSL which AT&T stopped selling in violation of various government contracts.

Starlink in practice is 10-200Mbps. Here's their specifications: https://www.starlink.com/legal/documents/DOC-1138-34130-60

Re: Lasers enable satellite internet backbone, might remove need for deep-sea cables

#70
post #15
post #9

Earlier quoted context omitted.

> more resilient, both to natural phenomena, equipment failures and sabotage. I think you're understating the risks from geomagnetic storms. In comparison to satellites, fiber optic cables seem like they'd be relatively unaffected even if the equipment attached to them needs replacement.

Perhaps the ocean is protective to some degree, but beyond very short lengths undersea cables have powered repeaters that draw considerable current, and which would plausibly be destroyed if the base stations are too.

I would not say "very short lengths", because undersea cables without powered repeaters (only with optical amplifiers) are possible until a few hundred kilometer.

But you are right that transoceanic cables need powered repeaters.

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