back to article Forget that Loon's balloon burst, we just fired 700TB of laser broadband between two cities, says Alphabet

Engineers at Alphabet's technology moonshot lab X say they used lasers to beam 700TB of internet traffic between two cities separated by the Congo River. The capitals of the Republic of the Congo and the Democratic Republic of Congo, Brazzaville and Kinshasa, respectively, are only 4.8 km (about three miles) apart. The …

  1. Anonymous Coward
    Thumb Up


    Putting aside Google's deplorable practices, Alphabet's X and other projects are truly great. They are, in many ways, the Bell Labs of today.

    Also +1 for frickin lasers.

    1. MyffyW Silver badge

      Re: X

      +1 for frickin lasers and another +1 for avoiding the river where the endangered sharks live.

      1. MiguelC Silver badge

        Re: X

        Being in the middle of Africa, 360kms from the ocean, there are no sharks available, but....

        Lasers on crocodiles --> mobile net!

        1. Tom 7

          Re: X

          Bull sharks have been found 2500 Km up the Amazon!

    2. Warm Braw

      Re: X

      Probably fair to say, though, that this is as much of a fix for a political issue as a technical one. There have been plans for a bridge for at least 30 years which could carry comms as well as road and rail traffic.

      While it's tempting to use technical fixes to work around such issues, politicians don't always like being cut out of the deal so it will be interesting to see whether/how this becomes commercialised.

      1. Fruit and Nutcase Silver badge

        Re: X

        You want a Bridge?

        Boris likes big building projects - and he also knows people who buildplan Bridges.

        But you'll have to pay for it yourself as Boris has redirected the UK overseas aid budget. But it will cost you - his garden bridge cost over £40 million to do the preliminary planning

      2. Tom 7

        Re: X

        You could probably put up a couple of pylons and string FO cable between them for not many beers at all.

  2. Mike 137 Silver badge

    Laser comms

    We were experimenting on this at UCL in London in the mid-'80s. The biggest problems we encountered were not technological but practical - maintaining aiming accuracy and pigeons roosting (&c.) on the kit.

    1. Anonymous Coward
      Anonymous Coward

      Re: Laser comms

      Could you not solve the pigeon problem by making the laser a bit more powerful?

      I suspect that's how they solved the animal interference problem here too :).

      1. Mike 137 Silver badge

        Re: Laser comms

        "Could you not solve the pigeon problem by making the laser a bit more powerful?"

        Zapping live pigeons still interrupts the signal, and pigeon droppings don't burn off optical glass as they're essentially non-combustible. Plus the weight of roosting pigeons can deflect the laser so its beam misses the detector. At the distances involved a very small angular deflection results in a large movement at the detector.

        If I remember rightly the transmitter was on the roof of the UCL electronics building in Malet Street and the receiver was on the roof of Kings College on the Strand about 1 km away, but even over that short distance, angular aiming accuracy has to be very high.

        1. Friendly Neighbourhood Coder Dan

          Re: Laser comms

          Have you considered publishing your research on bird shit and lasers?

          You would definitely be considered for an ignobel prize :-)

        2. Fruit and Nutcase Silver badge

          Re: Laser comms

          How about using gyros for stability?

      2. Fruit and Nutcase Silver badge

        Re: Laser comms

        Could you not solve the pigeon problem by making the laser a bit more powerful?

        It's Africa - Vultures are significantly bigger than pigeons.

        1. Anonymous Coward
          Anonymous Coward

          Re: Laser comms

          OK, so a LOT more powerful.

          A bit dodgy for local air traffic until it's aimed, but, as you say, it's Africa.


          1. Fruit and Nutcase Silver badge

            Re: Laser comms

            It's a good thing that Ostriches are flightless

    2. Giles C Silver badge

      Re: Laser comms

      I used this a few years ago (probably about 10) the reason for this was connecting two buildings separated by a car park, there was a single duct between them but they wanted a redundant connection.

      We had a couple of the laser was too powerful (we gave it sunglasses) the second was in freezing fog it refracted to the point of not working - not a problem in Africa,

      But it did work and the signal did transmit for a for years until someone finally paid to run a cable for a kilometre round the site to give it redundancy.

  3. Kerregan

    Standards of measure

    A US quarter measuring 5 cm? That’s what happens when you don’t stick to official Reg standards..

    1. Annihilator

      Re: Standards of measure

      I thought the same, then I thought that maybe it’s the area - 5cm^2 would still be a pretty big quarter though.

      1. Stumo

        Re: Standards of measure

        Using the engineering method of π being "a bit more than 3", πr²=5 gives r of 1cm and a little bit... Doesn't seem that off for a quarter? It's been a while since I've been in the USA mind...

        1. Paul Kinsler

          Re: Standards of measure

          And don't forget - a quarter has two sides! :-)

          1. Insert sadsack pun here

            Re: Standards of measure

            "And don't forget - a quarter has two sides! :-)"

            I think you'll find it has three.

            1. Timo

              Re: Standards of measure

              I might be able to find 5 sides: top, bottom, edge, inside, outside

        2. imanidiot Silver badge

          Re: Standards of measure

          Indeed, apparently (according to google) a US quarter dollar coin is 0.955 in, 24.26 mm, 0.1733 linguine in diameter. Which is 4.662 square centimeters. Unfortunately an area of that size doesn't even register (heh) in the smallest of El Regs area units the Nano-Wales. So that's an oversight to begin with.

  4. codejunky Silver badge


    A coms group working in the Congo with lasers. I wonder if there was an ape using sign language and king Solomons mines.

    Might have to watch that film again soon

    1. Anonymous Coward
      Anonymous Coward

      Re: Ha

      "Might have to watch that film again soon"

      George of the Jungle ?

      1. codejunky Silver badge

        Re: Ha

        Congo. Not a great film but seems to work for light entertainment

  5. John Brown (no body) Silver badge

    search for each other, detect the other’s beam of light

    So, while these high powered lasers are searching for each other, they're pointing all over the place until they eventually meet? Is the burned swathe of vegetation and dead bodies between the two?

    1. elsergiovolador Silver badge

      Re: search for each other, detect the other’s beam of light

      Probably that's why they testing it in Africa...

  6. elsergiovolador Silver badge


    Are they doing this in Africa, because there would be no repercussions if things go wrong, aka the laser fries the city?

    Or they don't want to pay Western wages?

    Or both?

  7. xyz123 Silver badge

    This is Google.

    Given the speed of light, each bit of data will have taken a billionth of a second or so to cross the distance.

    I'm still betting they could emit the first bit of data and cancel the project before it hit the destination.

    1. FILE_ID.DIZ

      We're not talking about a Fox TV series here, getting canceled three episodes into their first season.

  8. ComputerSays_noAbsolutelyNo Silver badge
    Paris Hilton


    "That's apparently because the fiber backbone to Kinshasa has to route more than 400 km (250 miles) around the river – no one wanted to put the cable through it."

    The article mentions that no cable exists that runs through the river,

    but why don't they just run a cable through the river?

    I guess laser comms would have proper real-world applications, e.g. connecting a valley-floor settlement with a settlement up a steep mountain-side.

    But two cities straddling a river?

    That is Google showing-off its technical capability,

    but not connecting Africa to the internet

    1. Anonymous Coward
      Anonymous Coward

      Re: Why?

      River beds aren't all sunshine and roses, especially if they lack flood control, so the issues may include local geology as well. That said, free air communications links tend to suffer exponential losses in inclement weather.

      As an alternative someone could trial landing a string of cheap POF(plastic optical fiber) and a bucket of rocks on the river bottom and just sending a canoe across every time it dies.

      But hey, why not do both? even if it works 6 days a week, it will pressure the incumbent telco to drop it's rates, and profide alternate paths for better burst speed and resilience.

      1. Insert sadsack pun here

        Re: Why?

        You also need to have a dry, power-fed, secure, vacant landing site on each bank of the river, and then a way to connect each landing site with the comms infrastructure in that country.

        1. Tom 7

          Re: Why?

          They've just landed the Grace Hopper cable in Bude - it was in a very large puddle when last seen.

  9. Mike 16

    Animal Interference

    Dunno about Africa, but the main hazard of animal driven damage to telecom structure here in the U.S. seems to be certain bipeds that like to use pole-mounted telecom gear for target practice.

    Meanwhile I can't be arsed but maybe someone could calculate how many Aldis Lamps would be needed to accomplish this task.

  10. Fruit and Nutcase Silver badge

    [Big] Cat Videos?

    How much of that 700TB consisted of Big Cat Videos?

  11. Fruit and Nutcase Silver badge

    Pigeon v Broadband in SA

    Anyone know if the broadband situation has improved in South Africa?

    portable storage capacity has increased several fold, so may be the pigeons still have the edge

    1. Giles C Silver badge

      Re: Pigeon v Broadband in SA

      I haven’t dealt with Telkom for about 8 years (it was a few jobs ago) but I remember the best bit was the call centre supporting international connections couldn’t phone outside of the country. Which was great when I am sitting in an office in the UK trying to fix a network problem in Cape Town.

      We used to have to give them the mobile number of one of the office managers to relay information through…

POST COMMENT House rules

Not a member of The Register? Create a new account here.

  • Enter your comment

  • Add an icon

Anonymous cowards cannot choose their icon

Other stories you might like