back to article Facebook to surround all of Africa in optical fibre and tinfoil

Facebook has backed a new submarine cable that it says will circumnavigate Africa and deliver three times more capacity than is currently connected to the continent. The forthcoming 2Africa cable will be 37,000km long, with one end starting in the UK and touching Portugal before reaching in 19 African nations, Oman and Saudi …

  1. Mike Shepherd
    Meh

    Can someone explain?

    ...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?

    1. robidy Silver badge

      Re: Can someone explain?

      Would be cool to know more :)

      1. Steve Davies 3 Silver badge

        Re: Can someone explain?

        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?

        1. JJKing Silver badge
          Thumb Up

          Re: Can someone explain?

          I am sure there are some unemployed ex-SAS operators that would like an all expenses paid PLUS all the pirates you can shoot ocean cruise.

          1. WolfFan Silver badge

            Re: Can someone explain?

            There are active duty RN personnel in the area. Don’t know if the SAS is around, but there’ll be Marines on some of the ships. And at least one US Navy SEAL team is in the general vicinity.

            1. Rol Silver badge

              Re: Can someone explain?

              It's Nigerian waters you want to be worried about. Far more incidence of pirating than Somalia.

        2. WolfFan Silver badge

          Re: Can someone explain?

          The Kenyans, the Indians, and the Chinese are paying very close attention to the Somali pirates. The Kenyan navy is hunting them at sea with Indian, Chinese, and some American, British, and French naval assistance. The Kenyan army is going up the coast and thumping pirate ports (a.k.a. ‘fishing villages’). The pirates and their friends dislike this so much that they’re carrying out a terrorist campaign in Kenya, which has merely made the Kenyans even more pissed off. Some units in the Kenyan army still carry battle honors from when they were units in the King’s African Rifles; at least one such unit has fought pirates/terrorists in more or less the same place where they fought Italians in 1941, and so has a second battle honor with the same name.

          There is also a pirate problem in the Bight of Benin and adjacent areas; the Nigerian armed forces are doing a lot of pirate hunting, with American, British, and other assistance. The Nigerians are even more pissed off than the Kenyans, the pirates in West African waters are annoying oil people (there is, or was, a write-up on that in the BBC’s “long reads” section) and that is costing them _money_.

          If someone tried to hit a cable layer, they’d better pray that they get caught by American or British forces, the Kenyans and the Nigerians are taking very few prisoners.

        3. Chris G Silver badge

          Re: Can someone explain?

          Aluminium has about 61% of the conductivity of copper but is one third the weight, it needs a larger cross section to equal the same conductivity of copper/cm but is still lighter if that is a consideration for an undersea cable.

          Regarding pirates, a good friend of mine who is an ex Royal Marine has done maritime security for the last decade and I am sure will be willing to give FB a quote.

    2. Flocke Kroes Silver badge

      Re: someone explaining

      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.

      1. Mike Shepherd
        Happy

        Re: someone explaining

        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?

        1. Jon 37

          Re: someone explaining

          Power is sent over large distances across the cables. You just have one power wire in the cable, and the amplifiers are wired in series. So for a US-UK fibre, the landing station in the UK might generate +1000V DC, with the 0V line from the power supply connected to the ground. Then the landing station in the US generates -1000V DC, with the 0V line from the power supply connected to the ground. This gives 2000V (less the ground return losses) across the cable, which has to cover all the losses in the cable and power all the repeaters. (I forget the exact voltage I read about, but I think I got the number of digits correct).

          Also, modern amplifiers don't use light->electricity->light conversion. They have fully optical amplifiers.

          So they use electricity to power a laser, and that laser light goes into a magic box that works in ways I don't understand. The incoming signal goes into that magic box and the amplified (i.e. brighter) signal comes out.

          1. JJKing Silver badge
            Boffin

            Re: someone explaining

            Why not ask the Orange Idiot at 1600 Pennsylvania Ave. After all, he knows everything about everything.

          2. Kernel Silver badge

            Re: someone explaining

            "So for a US-UK fibre, the landing station in the UK might generate +1000V DC, with the 0V line from the power supply connected to the ground. Then the landing station in the US generates -1000V DC, with the 0V line from the power supply connected to the ground. "

            I think you're missing a zero in those numbers - IIRC the Southern Cross cable, on its NZ to Hawaii section, feeds somewhere in the region of 12.5kV from each end.

            A rough idea of the required total feed voltage (at least for the cables I'm familiar with) can be determined by the formula 'cable length'/n, where n = 50 (volts needed to power each amplifier) times 60 (km, the approximate distance between amplifiers).

            Optical amplifiers are based on a short (a few metres) of optical fibre that has been doped with a small amount of Erbium atoms - hence the the fact that they are normally referred to as EDFAs - Erbium Doped Fibre Amplifier. Other dopants can be used, which produce amplifiers that have a different working frequency range.

            A 'pump laser' (up to three) within the amplifier is used to excite some of the electrons in the Erbium atoms up from their normal rest energy level to a level that is two steps more energetic. The electrons which have been pushed up then almost immediately drop back one level, leaving them in the level that is one step up from their rest state - they are comparatively stable at this level. The initial drop back from the highest level generates spurious photons, which cause noise in the optical signal and limit the amount of amplification stages you can have while still retaining a workable signal to noise ratio.

            The electrons that have been left sitting in a stable state, one level higher than their rest state, will, when struck by a photon from the incoming signal drop back to their rest state, in the process of which they emit a photon that is an exact copy of the signal photon that collied with them. This new photon, plus the original one, then go on to repeat the process, causing the desired signal to be amplified.

            Needless to say, there's a hell of a lot of devil in the details between my simple description above and actually building a field deployable EDFA, but in any DWDM system they are probably the most common optical block present.

            No, I'm not the Orange Idiot at 1600 Pennsylvania Ave., I just spent many years working for a vendor of such toys as a support engineer for DWDM systems.

            1. Gavin Park Weir

              Re: someone explaining

              I would have thought that there will need to be both EDFAs and proper reprocessing points? My recollection from 20 years ago is that there are 2 forms of signal reduction in fibre optics:

              Attenuation - the light getting dimmer over distance

              Spreading/scattering - gradual elongation of the "1" light pulse into the "0" dark due to boucing off the wave guides and glass particles etc.

              EDFAs would only address attenuation not signal spreading.

          3. Persona Silver badge

            Re: someone explaining

            "goes into a magic box that works in ways I don't understand"

            Upvoted for describing how it works in a way that I can understand too.

        2. eldakka Silver badge
    3. WolfFan Silver badge

      Re: Can someone explain?

      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.

      1. tip pc Silver badge

        Re: Can someone explain?

        "Only silver is better than copper"

        you'll find that Gold is better than both Silver and Copper.

        1. WolfFan Silver badge

          Re: Can someone explain?

          Anyone who has the budget to use gold for cable is some I want to know better.

          1. Rol Silver badge

            Re: Can someone explain?

            Might want to have a listen to Cabin Pressure. An hilarious radio program that ran some years ago on Radio 4.

        2. Ken Hagan Gold badge

          Re: Can someone explain?

          Surely you want directional oxygen-free single-crystal cables?

        3. rcxb Silver badge

          Re: Can someone explain?

          Material resistivity σ (S/m) at 20 °C

          Silver 1.59×10^−8

          Copper 1.68×10^−8

          Gold 2.44×10^−8

        4. Doug_S

          Not true

          Silver is more conductive than gold. The reason gold is used a lot in electronics isn't because it is most conductive, but because gold doesn't tarnish/rust/corrode. It is also easier to make very thin plating for gold, so gold plated whatever likely costs less than silver plated even where the corrosion wouldn't be an issue.

          Copper is more conductive than gold as well. It is the corrosion resistance and ability to use very thin plating that wins the day for stuff like gold plated contacts on a DIMM and so forth.

          Conductivity at 20C in siemens/meter:

          Silver 6.30×10^-7

          Copper 5.96×10^-7

          Gold 4.10×10^-7

          Aluminum 3.5x10^-7

          1. AdamT

            Re: Not true

            I used to work for a submarine cable manufacturer and, yes, there was a lot of gold plating (for corrosion resistance). Also, there were no connectors - everything had to be soldered or otherwise physically bonded. Soldering to gold plated pins is a lovely experience - even I could get the textbook solder fillet shape!

      2. KLane
        Headmaster

        Re: Can someone explain?

        The main reason aluminum is bad for house wiring, is that copper is 'springy' and aluminum isn't, at least far less than copper. When the wire is connected to the outlet, switch, etc., it is usually under a screw. The copper will push back when compressed, maintaining a good electrical connection, whereas aluminum doesn't. This leads to a connection that will degrade over time, and cause a 'hot spot' where the wire meets the outlet or switch, increasing the risk of fire.

        1. Kevin McMurtrie Silver badge

          Re: Can someone explain?

          Actually, it's the oxide layer. Household power is right about where the oxide layer starts conducting so it's prone to getting hot from power losses. It needs to be clamped extremely tightly or it needs to operate in the KV range where it will weld itself.

          Another option is copper clad aluminum. If ever you see wire at the hardware store that doesn't cost a fortune, it's that. It can even be soldered once.

          For a an undersea cable, I imagine they spend a bit extra for good clamps or brazed connections to use aluminum. It would be trivial compared to the cost of copper.

    4. Mike 137 Silver badge

      Re: Can someone explain?

      From Conductivity Of Metals Sorted By Resistivity

      Copper pure IACS 100%.

      Copper deoxidised IACS 85%

      Aluminium 99.99% pure IACS 64.95%

      However aluminium is about a quarter the price of copper, so and Al wire 1.3 times the area (1.144 times the diameter) would have equivalent resistance per length to deoxidised copper and be a lot cheaper. Does make sense, except possibly for the greater difficulty of making long term reliable connections at the ends.

  2. Detective Emil

    For completeness …

    … 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.

  3. Pascal Monett Silver badge

    My gast is well and truly flabbered

    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 ?

    1. JJKing Silver badge
      Facepalm

      Re: My gast is well and truly flabbered

      I hope this cable doesn't get connected to all those Nigerian princes and banks that are full of dead peoples money. I've had enough emails from them in this lifetime thanks.

    2. Persona Silver badge

      Re: My gast is well and truly flabbered

      It's just their long term plan to extract money from the citizens of Africa and gain profit parity with the more developed continents.

  4. Dave Pickles

    Why don't they join the ends?

    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...

    1. dirtygreen

      Re: Why don't they join the ends?

      Because the ends are already effectively joined anyway, by existing cables. You can already view websites in Spain with no problems from Blighty, yes?

    2. rcxb Silver badge

      Re: Why don't they join the ends?

      Brits sure do like their ring circuits, don't they?

      1. s2bu

        Re: Why don't they join the ends?

        Telecom sure loves SONET rings too!

      2. Muscleguy Silver badge

        Re: Why don't they join the ends?

        We also take rings from rings. This 3 bed house had an extension built to get that 3rd bedroom and move the kitchen into it and get a dining room. It was unconsented and there's various naughtiness. We got a leak in the extension flat roof on our side but the water came into next door: No party wall in the roof.

        The power for the kitchen (except interestingly for the Oven/range) is looped off the upstairs ring. The water did come through my roof, through the ceiling rose. BANG! I lost light upstairs and in the kitchen. I was cooking by headtorch.

        It's all fixed now, shiny new, insulated, roof covering. I could replace the blown ceiling rose and hey presto there was light. The ring still comes off upstairs.

        Oh yes. Years ago I was awaiting the Cable installers and had pulled the TV etc out of the corner. I pulled the downstairs sockets fuse and used the time to investigate why the socket there didnae work. There was a flash (insulated screwdriver in operation) and the light went out. There's a standard lamp fixed wire outlet along the wall and they had looped the socket from it, on the lighting circuit and fuses.

        I crawled under the house, found a connection box with a spare terminal in easy reach of the cable from the errant socket which they could have used. I used it after taking the single box out and chopping out a bigger hole to provide a double socket properly spurred off the socket ring.

        We also bought a standard lamp and actually used the outlet properly.

        Then there was the time I had to rebuild the shoddy, non Zed, back gate. The flex to the garage went across the top of the gate on a piece of wood. I lifted it to enable a new gatepost and there was flash. It was ordinary grey indoor flex and years of sunlight had destroyed the insulation. So a new gate also became run properly surface rated armoured cable to the garage. It goes along the ground: there's a small step from the back pavers to the drive and it runs in a custom channel made from some angle iron then up the gatepost and into the garage. The angle iron protects it from rubbish bin wheels. It does not rub the cable.

        The Zed gate has been there for nearly 20 years now and is still going strong. Just replaced a broken leaf hinge. It's good for another 5-10 years at least. I do things properly.

        1. Chris G Silver badge

          Re: Why don't they join the ends?

          @Muscleguy

          Your cooker/range supply has had to be seperate supply and fuse/breaker and at least 25amps for years now, in fact it might even be higher by now ( I have been out of the UK for the last twenty years).

          I have a cooker socket in my Spanish house that is on the same circuit and breaker, as several sockets and a couple of lights, a Brit sparks would have a fit looking at that.

          1. katrinab Silver badge

            Re: Why don't they join the ends?

            Mine is 32A, installed about 10 years ago.

        2. Anonymous Coward
          Anonymous Coward

          Re: Why don't they join the ends?

          You do things properly apart from using a voltage tester screwdriver on a known bad socket after taking down a single circuit breaker!

          The first thing I do when taking a socket cover off is check the line is at earth potential before fixing/replacing. It's amazing how many sockets in a house can be coming from a different circuit to the one expected.

          I hope you upgraded to full RCD protection as well at the same time, it doesn't sound like the external cable (wow!) or the lighting circuit had it.

  5. Len Silver badge
    Paris Hilton

    Choice of countries

    I'm somewhat surprised by the choice of countries. For instance, why is a country like Namibia (with its fairly large mining, manufacturing and banking sector one of the rising stars of the continent) not included whereas a non-African country like Oman is?

    A connection to Luanda in Angola (the world's most expensive city after overtaking Hong Kong) would make sense too. Luanda is also where South Atlantic Cable System (SACS) comes on land from Brazil so it could bring 2Africa countries closer to South America. The same argument goes for Cameroon where the SAIL from Brazil comes on land.

    Historically the reason that every African coastal country wanted its own connection was that they didn't always trust their neighbouring states. The ties between Namibia and South Africa are pretty good as far as I know so perhaps that traffic can just continue over land. Are there considerations that I'm not seeing?

    1. itzman

      Re: Choice of countries

      I'm somewhat surprised by the choice of countries. For instance, why is a country like Namibia (with its fairly large mining, manufacturing and banking sector one of the rising stars of the continent) not included whereas a non-African country like Oman is?

      Namibia has good fibre links to South Africa, and not a lot of population. Its also a hard country to get power to and from

      Oman is full of rich people needing to play online video games.

      I am sure that people laying this cable have done a full market survey of the data requirements of every place versus the cost of connecting to it.

  6. Marketing Hack Silver badge
    Black Helicopters

    Undersea fiber-optic cable? Nice cover story!!

    It will last right up until the attached flux capacitor is turned on, and Africa disappears into a dimensional vortex.

    1. anthonyhegedus Silver badge

      Re: Undersea fiber-optic cable? Nice cover story!!

      Down with Fibre! Fibre rings create covid-21 rays which will bring about mass surveillance of the Africans! Bill Gates and Jeff Bezos are in cahoots to make and sell GPS-chips that'll be injected and monitored by the Fibre, which will emit death-rays and 6G weaponised otters.

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