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Undersea Cable Repair Via 19th Century Tech
An anonymous reader writes to mention a story going across the wires about an old-fashioned way to fix a modern convenience. Taiwanese boaters are using simple hooks to fish up the fiber-optic cables damaged in an earthquake late last year. The outage that resulted kept millions of users offline in half a dozen countries around the Pacific rim. From the article: "They work 24 hours a day but the weather can hinder their progress. Walters said one ship is waiting for 30 to 40 mile-an-hour winds (48 to 64 kilometres- an-hour) to die down in the Bashi Channel. The winds have stirred up 10 to 12 metre waves ... After arriving at the scene they survey the ocean bottom to assess whether the contour has changed, and the degree of sediment movement. Then the traditional tools are brought out. A rope with a grapnel on the end is played out, down into the depths, and towed over the sea floor until tension registers on a graph on the ship, indicating contact has been made with the cable. Today's fibre optic cables are just 21 millimetres in diameter."
I beg to differ. There are devices known as OTDRs (optical time-domain reflectometers). Essentially, you shoot a pulse of light down the carrier and start a high-speed counter. The difference in refraction (say, a break in the cable or the end of the cable) causes a reflection that is detected at the device. Using the elapsed time, you get the distance to the break.
r eflectometer
Check out this link http://en.wikipedia.org/wiki/Optical_time_domain_
I also saw a documentary on the Science channel about these ships. The whole process of fixing the break is sterile and professional. They use fusion splicers, which fuse the two ends with an electric arc. Fascinating stuff.
-- Posted from my parent's basement
21 mm == 2,1 cm (which is more than half an inch)
But I can image that those fibre cables are bundled and come with a undersee resistant coating.
Actually, it didn't keep people offline in Asia. It just made international Internet connections incredibly slow. Using the Internet for national sites, which is the vast majority of Internet use, was barely effected. Here in China, nobody at my American-owned computer company even cared, except that MSN chat was pretty spotty for a couple days.
Slashdot: providing anti-social weirdos a soapbox, since 1997.
The don't just have fibers either. There is a central core; usually steel cable. Then they have power feeds for the repeaters. Every 50~100km, they'll have a repeater pod. Finally, they have the fibers and, on top, a thick metal or plastic sheath.
What's really amazing about undersea cables is that no one outside the industry really thinks about them. Sprint and ATT give everyone the impression that sats take care of most comms. However, the opposite is mostly true. The vast majority of comms are way too time sensitive to allow the the delay imposed by satcom.
I'd rather you do it wrong, than for me to have to do it at all.
But given the bandwidth capacity of the routes, we should be able to find it. It cant be rocket science in undersea anyway.
Eclipse PDE and Me
Another, related thing:
I don't know how americans mesure winds, but here in Sweden we always mesure them in m/s, and nothing else.
48 to 64 kilometres-an-hour would then be 13 to 18 m/s
And that doesn't seem to be very much, now(saturday morning) the winds at the coast where I live are 18-22 m/s, and it isn't even very much.
Actually, there is also a 17mm version of the cable. Those diameters are for the cable used in the deep-sea portion of the cable system. Any cable layed near shore has additional "armoring" layers of steel wires to protect it from anchors and what not. This armoring brings the diameter up substantially. By the way, there are only either 4 or 8 fibers pairs in a single cable. Even so, these systems transmit incredible amounts of information (10GB/s) per fiber pair. You'd be amazed at how many of these systems are in the water. http://www.tycotelecom.com/SystemSupply/content.as p?page=subSystems.asp