109
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 28 Aug 2024
109 points (94.3% liked)
No Stupid Questions
36055 readers
1543 users here now
No such thing. Ask away!
!nostupidquestions is a community dedicated to being helpful and answering each others' questions on various topics.
The rules for posting and commenting, besides the rules defined here for lemmy.world, are as follows:
Rules (interactive)
Rule 1- All posts must be legitimate questions. All post titles must include a question.
All posts must be legitimate questions, and all post titles must include a question. Questions that are joke or trolling questions, memes, song lyrics as title, etc. are not allowed here. See Rule 6 for all exceptions.
Rule 2- Your question subject cannot be illegal or NSFW material.
Your question subject cannot be illegal or NSFW material. You will be warned first, banned second.
Rule 3- Do not seek mental, medical and professional help here.
Do not seek mental, medical and professional help here. Breaking this rule will not get you or your post removed, but it will put you at risk, and possibly in danger.
Rule 4- No self promotion or upvote-farming of any kind.
That's it.
Rule 5- No baiting or sealioning or promoting an agenda.
Questions which, instead of being of an innocuous nature, are specifically intended (based on reports and in the opinion of our crack moderation team) to bait users into ideological wars on charged political topics will be removed and the authors warned - or banned - depending on severity.
Rule 6- Regarding META posts and joke questions.
Provided it is about the community itself, you may post non-question posts using the [META] tag on your post title.
On fridays, you are allowed to post meme and troll questions, on the condition that it's in text format only, and conforms with our other rules. These posts MUST include the [NSQ Friday] tag in their title.
If you post a serious question on friday and are looking only for legitimate answers, then please include the [Serious] tag on your post. Irrelevant replies will then be removed by moderators.
Rule 7- You can't intentionally annoy, mock, or harass other members.
If you intentionally annoy, mock, harass, or discriminate against any individual member, you will be removed.
Likewise, if you are a member, sympathiser or a resemblant of a movement that is known to largely hate, mock, discriminate against, and/or want to take lives of a group of people, and you were provably vocal about your hate, then you will be banned on sight.
Rule 8- All comments should try to stay relevant to their parent content.
Rule 9- Reposts from other platforms are not allowed.
Let everyone have their own content.
Rule 10- Majority of bots aren't allowed to participate here.
Credits
Our breathtaking icon was bestowed upon us by @Cevilia!
The greatest banner of all time: by @TheOneWithTheHair!
founded 2 years ago
MODERATORS
Lasers work really well in space for secure sat-to-sat data links, but are a lot less viable on Earth's surface due to diffraction and weather, nevermind the limits of the visible horizon for any height of a communications tower. For pretty much any scenario where laser comms would be considered, microwave RF links would likely be just as good, cheaper, and more commonly deployed and understood by telecom engineers. The only exception is when absurdly high bandwidths are needed, which is where lasers rule.
But using RF links across thousands of kilometers of oceanic waters? For that, you must construct additional pylons on floating islands to repeat the signal. Otherwise, the only RF signals that could reach land would be too low frequency to carry much bandwidth.
For reference, when the German Aerospace Center (DLR) set the world record in 2016 for free-space optical communications, they achieved 1.72 Tbits/sec over a distance of 10.45 km. Most optical systems observe a bandwidth/distance relationship, where at best, shooting the signal farther means less available bandwidth, or more bandwidth if brought closer. This is a related to the Shannon-Hartley theorem, since the limiting factor is optical noise.
So if 1.72 Tbits/sec at 10 km is the best they achieved in free air in 2016, then that pales in comparison to the undersea fibre cables of 2006, where a section of the SHEFA-2 Scottish-Faroese cable runs unamplified for 390 km and moves 570 Gbits/sec aggregate.
In short, free-space lasers are fast and long-distance. But lasers within fibre cables are much faster and cover even longer distances. They're not even in the same league.