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The Dunant subsea cable

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Re: The Dunant subsea cable

#231

Post by retzkek »

jxcl wrote: post #127
thomaslangston wrote: post #122

Earlier quoted context omitted.

More feasible would be transmitting neutrinos or some other signal that would not be blocked by the Earth.

> More feasible If they don't interact with the thousands of miles of earth between the source and the destination, they probably also won't interact with the receiver! :p Imagine the retransmission rates! https://en.wikipedia.org/wiki/Neutrino_detector

The MINERvA experiment at Fermilab already demonstrated communication with neutrinos, admittedly over short distance: "The link achieved a decoded data rate of 0.1 bits/sec with a bit error rate of 1% over a distance of 1.035 km, including 240 m of earth."

https://arxiv.org/abs/1203.2847

Anyone from an HFT firm who wants to look into a partnership researching a neutrino link to the CME data center feel free to reach out :)

Re: The Dunant subsea cable

#232

Post by Retric »

potiuper wrote: post #222
wmf wrote: post #191

Earlier quoted context omitted.

Because HFT helps the rich AF get richer but Starlink benefits normal people?

Satellite internet already exists; StarLink's defining feature is lower latency both by being in a lower orbit and inter-satellite links. It does benefit consumers by introducing another satellite internet competitor, but how many "normal" people want to rely on satellite internet or, if they do, care about a few extra 100s of ms of latency? (Inter)-National wireless companies have a tendency to consolidate and lobby…

The ping on satellite internet is usually around 640 ms as it’s a ~45,000 mile round trip, worse the bandwidth is terrible. That kind of latency breaks a lot of assumptions in the modern web. Dropping to ~20ms and dramatically upping the bandwidth is a huge win for rural internet users.

PS: I am on the waiting list for starlink.

Re: The Dunant subsea cable

#233

Post by russdill »

mmmBacon wrote: post #164
O5vYtytb wrote: post #56

Earlier quoted context omitted.

My bet is on tech like Starlink with inter-satellite communication. Starlink should have lower latency with space lasers compared to fiber.

Starlink satellites are in orbit 550km high. So any journey would add at least 1100km. Moreover not sure that a single satellite would be able to hit another one across transpacific distances and may need to go through multiple hops to get there. Each hop will add latency since signal needs regeneration. So it’s not clear to me a swarm of satellites is a real winner from a latency POV. Furthermore, given costs to put…

1100km / c is 3.7ms. In free air, light speed is 50% faster. So long as the distance you are covering is more than 2200km, you'll overcome that. Of course, there's also the consideration that there can also be a lot of hops in terrestrial links and it's often very far from a straight line path.

Re: The Dunant subsea cable

#236

Post by walrus01 »

lifeisstillgood wrote: post #107

Old timer story - years ago, Demon Internet (my old employer) was beginning to enter super-growth and wanted to really set itself up for trans-atlantic connections. So they decided to buy a T1 - 45Mbps link across the atlantic. Now it turns out that BT had only ever resold fractions of T1s - they had never actually had anyone want a whole one. And as such their sales commissions did not cap out. So, we rang up, a sal…

On a slightly later time scale, I still remember the time I first saw a OC192 linecard in a router in person, at a major IX point, and how incredibly impressed I was. This was in the era when a transcontinental, or submarine transatlantic OC192/STM64 circuit was an astonishingly huge amount of money every month.

Re: The Dunant subsea cable

#237

Post by ISL »

BelenusMordred wrote: post #130
idlewords wrote: post #58

Earlier quoted context omitted.

You gotta bore for that sweet latency win. A chord tunnel between San Francisco and Hong Kong would save 1300 miles (20% improvement right there), and if you drill it straight enough, you won't even need a cable.

Please don't give the HFT's ideas, they'll probably do it and cause a half dozen tsunamis in the process.

If you don't like HFTs, this is an idea you'd probably like to give them. Nobody has ever drilled through the Mohorovicic. It is unclear whether or not it is possible to do so.

The most-likely outcome is a few happy geologists/geophysicists and a number of very-sad HFT underwriters.

https://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_disconti...

Re: The Dunant subsea cable

#238

Post by LargoLasskhyfv »

morei wrote: post #208
LargoLasskhyfv wrote: post #196

Earlier quoted context omitted.

Are you sure about the necessary regeneration? Let me hand wave from the dark skies here for a moment: 1.) Think of the precision mirrors in the so often mentioned EUV-lithography equipment from ASML for latest generation chips from TSMC. 2.) Now imagine something like that on board of a satellite, maybe smaller. 3.) Have 2.) moveable with sufficient precision to bounce the rays from satellite to satellite in realtim…

Those 'precision EUV mirrors' achieve a reflectance of about 70% i.e. they aborb ~30% of the EUV light that reaches them. :) More seriously, those mirrors are special because they use bragg reflectors to handle 13.5nm light. They're not special for their precision, nor their reflectance. Setting that aside, the major problem with your proposal is that laser still have significant bream spreading. So the mirrors would…

Hrm. Taken from https://www.asml.com/en/technology/lithography-principles/le... :

> Flatness is crucial. The mirrors are polished to a smoothness of less than one atom’s thickness. To put that in perspective, if the mirrors were the size of Germany, the tallest ‘mountain’ would be just 1 mm high.

edit: What I meant to say was rather something with that precision reflecting whichever wavelengths are used for laser communications. Which would be infrared, I guess? Or are we talking Maser?

Re: The Dunant subsea cable

#239

Post by cuonic »

markphip wrote: post #31

I know there are many of these cables that have been around for years, but I am curious how are they physically secured? Especially where they transit from ocean to land? Is there some long underground/sea tunnel of conduit that the cable is routed through to the basement of some building? Or if you are walking along the beach somewhere is there just some cable running out of the ocean along the beach to some buildin…

As for physical security, some are only protected by simple manhole covers before reaching the actual technical building, here's an example in Marseille, France where SeaMeWe-4 (and others) lands: 43.261938, 5.37276 [0] but the landing points aren't exactly secret [1]. Here are some photos [2][3] and a video [4] of Dunant's arrival in France.

[0] https://www.geoportail.gouv.fr/carte?c=5.372494831681247,43....

[1] https://www.sigcables.com/index.php/cableliste/fiche_cable/5...

[2] https://twitter.com/jlvuillemin/status/1238414261774401537

[3] https://twitter.com/jlvuillemin/status/1238433769935319042

[4] https://twitter.com/jlvuillemin/status/1238479381145751553

Re: The Dunant subsea cable

#240

Post by ISL »

atonse wrote: post #136
jxcl wrote: post #127

Earlier quoted context omitted.

> More feasible If they don't interact with the thousands of miles of earth between the source and the destination, they probably also won't interact with the receiver! :p Imagine the retransmission rates! https://en.wikipedia.org/wiki/Neutrino_detector

And you'd also have to ignore all the insane amounts of noise coming from regular neutrinos wizzing about in the universe.

If you're sending neutrinos at a known energy from a known location and in a narrow time-coincidence window, you can hammer most backgrounds way down.

The low detection rate isn't so terrible either -- one only needs the bits that are detected to be tradably-correct almost-all the time.

The hard part is arranging to make enough money to fund the accelerator and detector.

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