Internet outage : understanding how they fix undersea cables

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  1. #1

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    Internet outage : understanding how they fix undersea cables

    Just found this interesting article in SLATE explaining how they're fixing the undersea cables that were broken during the earthquake:

    explainer
    How Do You Fix an Undersea Cable?
    Electrical repairs at 20,000 leagues.
    By Lindsay Goldwert
    Posted Monday, Jan. 8, 2007, at 4:27 PM ET

    Powerful earthquakes near Taiwan shut off international phone and Internet service for the Far East just after Christmas. Five repair ships have been working on the damaged undersea cables since late last week. How do you repair a cable that's lying across the ocean floor?

    Drag it to the surface. Earthquakes—like ships' anchors and fishing trawls—can cause undersea fiber-optic cables to malfunction or break many miles below the surface of the water. When this happens, a telecom operator has to find the location of the accident, hoist up the damaged part, and replace it with a new stretch of cable.

    First, the telecom operator has to locate the part of the cable that's no longer working. Cable engineers can figure out the general neighborhood of the problem based on the reported phone or Internet service outages. From terminal stations on shore, they can zero in on more specific coordinates by sending light pulses along the fibers in the cable. A working fiber will transmit those pulses all the way across the ocean, but a broken one will bounce it back from the site of the damage. By measuring the time it takes for the reflections to come back, the engineers can figure out where along the cable they have a problem.

    Once they know that, the company can send out a large cable ship with a few miles of fresh fiber-optic lines on board to make the repairs. If the faulty part of the cable is less than about 6,500 feet down, the crew will send out a submersible tanklike robot that can move around on the sea floor. A signal can be sent through the cable to guide the robot toward the problem spot. When the robot finds the right place, it grabs ahold of the cable, cuts out the nonworking section, and pulls the loose ends back up to the ship.

    The robot doesn't work in very deep water (with very high pressure). In those situations, the technicians aboard the cable ship use a grapnel, or a hook on a very long wire, to snatch up the cable from the sea floor. The grapnel uses a mechanical cutting and gripping device that can split the cable on both sides of the break and drag the loose ends to the surface. One end is hooked onto a buoy so it won't sink, and the other is hauled on board.

    The malfunctioning cable section can be fixed on board the ship. A skilled technician or "jointer" splices the glass fibers and uses powerful adhesives to attach the new section of cable to each cut end of the original—a process that can take up to 16 hours. The repaired cable is then lowered back to the seabed on ropes.


  2. #2

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    My brother works for a ship yard that builds undersea cable repair ships.

    The ships are great with the facilities equipment they have on board.

    Propellers that rotate 360 degrees, they do nine knots go sideways. Using GPS they can make on board computers that control all the engines, to compensate for the waves, and tides and stay geographically static in one point. In the article they do not mention how many beers it takes to repair one of the cables.

    What amazes me is that; they don't put cat5 cable all over the ship to all the quarters, and link everyone up for network games or on-ship entertainment. The network equipment (24 port switch) tend to be crap (Level One). This is why ships sink.

    Last edited by hk.com; 09-01-2007 at 03:53 PM.

  3. #3

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    Quote Originally Posted by hk.com:
    What amazes me is that; they don't put cat5 cable all over the ship to all the quarters, and link everyone up for network games or on-ship entertainment. The network equipment (24 port switch) tend to be crap (Level One). This is why ships sink.
    Are you trying to be facetious?

    There are some diagrams and nice animation if you want to see how submarine cables are laid & repaired:

    http://www1.alcatel-lucent.com/submarine/how/index.htm
    http://www.k-kcs.jp/english/installations.htm

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    very cool - explains it for the dumb users of which I have many !


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    Quote Originally Posted by MrMoo:
    Are you trying to be facetious?

    There are some diagrams and nice animation if you want to see how submarine cables are laid & repaired:
    What has that got to do with the quality of network onboard the ship laying the cable?

  6. #6

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    Quote Originally Posted by hk.com:
    What has that got to do with the quality of network onboard the ship laying the cable?
    First paragraph is response to your interesting logic: ships sink because they don't have good enough networking equipment to play games.

    The second paragraph links to pictures & animation for a clearer explanation than the OP's text.

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    I thought it was loose lips that sank ships.


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    Quote Originally Posted by MrMoo:
    First paragraph is response to your interesting logic: ships sink because they don't have good enough networking equipment to play games.

    The second paragraph links to pictures & animation for a clearer explanation than the OP's text.
    My point is that firstly there is no networking to support internal operation of the ship, which could greatly help the management and the quality of life of the crew. The only stuff they use is to drive the geo positioning systems and what they use "Level One" (even on shore they total crap and unreliable switch).

    My joke about ships sinking is related to fact that the "Level One" switches are not reliable to add they don't have components coated for outdoor use and use air circulation for cooling, which is likely to bring salty and moist air onto the PCB.