News: 1589532305

...aluminium conductors instead of copper, an innovation developed by Facebook and Alcatel as a way of reducing voltage drop along the very long transmission distances required of submarine cables. More voltage means the ability to keep more fiber pairs lit.

The "very long transmission distances" of optical fibre depend on currents through the cables?

Aluminium conducts better than copper?

Would be cool to know more :)

The extension of the 3rd rail network from Bournemouth to Weymouth was done on the cheap and used Auiminium 3rd rail. It has been wonderful in its unreliability especially in summer.

It isn't the panacea that many people think it might be. Jointing will be an issue.

Then there are the pirates operating out of Somalia. A slow moving cable layer will be a huge target for them will it not?

I wonder if FB has factored in the cost of paying the ransom's for the crew?

Optical fibres are almost completely transparent but over hundreds of kilometres that "almost" adds up to almost opaque. The light has to be converted to electricity, error corrected and converted back to light which costs electrical power. That power has to be transported hundreds of kilometres. You can offset the resistance losses in the conductors by increasing the voltage - at the expense of increasing the conductance losses in the insulator.

Copper is a better conductor than aluminium for the same cross sectional area. Increasing the area of the aluminium to match the conductivity increases the weight but as aluminium is much less dense the cable turns out needing fewer tons of aluminium than copper. Copper also costs far more per ton than aluminium.

Thanks for that. Can you say how power is distributed to the repeaters? Is it sent from various points along the shore or over large distances along the cables?

No, copper is better than aluminum. It also costs more and is heavier. Voltage depends, in part, on the diameter of the cable (that’s a gross oversimplification, the class I took on electrical transmission systems spent some time on the details) so that for a given weight of cable aluminum is thicker than copper and can support more voltage. For a given cost, you can make the aluminum cable thicker still. Only silver is better than copper. It also is vastly more expensive, and silver cable is used only for very specialized systems where cost is not a primary limiting factor.

Aluminum is sufficiently cheaper than copper that there was a fad for putting aluminum wires in houses and ships and other places. Someone forgot that aluminum also burns easier than copper. After several spectacular fires, they stopped doing that. Aluminum cable usually goes where professionals can keep an eye on it, in things like large motors and generators and very high voltage electric transmission cable. Underwater fires are unlikely, but difficult to extinguish, particularly as metal fires in general and aluminum fires in particular tend to burn very hot and to do things like disassociate the oxygen from water (or other substances; thermite is usually aluminum powder and iron oxide, a.k.a. rust, and burns by the aluminum liberating the oxygen from the rust) and use it to burn. And no, halon will NOT put it out, it stops burning when it runs out of fuel (aluminum) or oxidizer (water, in this case). Thermite will burn quite merrily in a vacuum, if you get it going... There would probably be a reason why no-one has run aluminum cable under water at this length before.

… the full list of backers is Facebook, MTN (a South African telco), Orange, Vodafone, China Mobile, and WIOCC (an African wholesaler of cable capacity). I’ve found nothing about relative levels of participation.

FaceBook actually doing something useful, and selflessly pledging open access.

Okay, sure, it will also be open access to FaceBook and it ad-slinging, privacy-violating platform, but still, it means people will be able to just surf the Internet, so not necessarily use FaceBook.

Wow. Has the temperature actually dropped a degree down in Hell, or is this just the visible tip of the iceberg of The Zuck's plan for world domination ?

From the map it seems it would be a simple matter to continue the fibre through the Straits of Gibraltar and make a complete loop. Then if (when?) there is a break, countries downstream of the break can be fed from the other end.

Or they could try continent-sized FDDI...