Date: 18-Jul-1986 1346 From: covert%covert.DEC@decwrl.DEC.COM (John R. Covert) Subject: Just when AT&T thought it was safe to go back into the water >From the Wall Street Journal, 26-June-86, included without permission. Survey: Sharks Prefer AT&T Lines By Wide Margin Over Sprint, MCI ------ ------ ------ ---- ----- -- ---- ------ ---- ------- --- By Bob Davis Staff Reporter of The Wall Street Journal Just when American Telephone & Telegraph Co. thought it was safe to go into the water, sharks began dining on its newest undersea telephone-communications cable. It seems the sharks just can't get enough of AT&T experimental underwater fiber-optic telephone cable near the Canary Islands. They munch on its plastic covering, gnaw on its electrical innards and eventually short-circuit it-even though they may electrocute themselves in the process. At least, "we came up with some pretty effective shark bait," says an AT&T spokeswoman. At first, AT&T engineers didn't know what was causing the cable failures. Then they raised the cable and found rows of shark teeth sticking out of it. "Sharks will always be attracted to magnetic fields," which the fiber-optic cables create, says James Barrett, an AT&T engineering official. Transatlantic Race That's the big problem because AT&T is hurrying to complete the world's first transatlantic fiber-optic cable by 1988. The cable uses glass fibers instead of copper wires to transmit conversation and data. AT&T's old cables generally are shark- free because they don't emit much magnetism. But a shark bite helped knock out the Canary Island fiber-optic cable for a full week. AT&T says it can combat the sharks by reinforcing stretches of the cable with steel wire and quickly patching breaks that occur. But the company's shark problem has attracted another kind of predator. Space Shark Communications Satellite Corp. (Comsat) a Washington, D.C., satellite company, is pressing Congress to spend $119 million next fiscal year on a new satellite system that will compete with fiber optics. Meanwhile, Comsat officials are turning AT&T fish difficulty to their own advantage: Shark attacks "may cause a delay of six months to a year," in laying AT&T's transatlantic cable, asserts John Evans, a Comsat vice president. AT&T denies any such delay. And even Comsat's lobbyist, Thomas Scully, doubts that Congress will swallow the fish story. He reasons: "If I were at AT&T and I saw an article saying the biggest problem facing fiber optics is that fish eat the cable, I'd say, "Boy, the satellite people are desperate." -30- Notes: The person from whom I originally received this article was immediately sceptical of the reports of magnetic fields from fiber optic cables. But unlike short-haul terrestrial fiber cables, where the fiber would not emit any fields, undersea cables must carry high voltage power to the undersea repeaters, which would result in both electric and magnetic fields around and along the cable. The article is further misleading in stating that old cables are shark-free because they don't emit much magnetism. It appears that the real reason here is more likely to be because the conventional cables are a larger diameter which the sharks can't so easily get their teeth around. And finally, experiments have shown that sharks are attracted to electrical fields which many of their prey emit. There is little to no data about magnetic fields and shark. I have, however, read articles about other animals using magnetic fields for navigation. /john From: nagle@netcom.com (John Nagle) Subject: Re: AT&T Ship Sets Trans-Oceanic Cable Installation Record Date: Mon, 11 May 92 07:48:04 GMT Organization: Netcom - Online Communication Services (408 241-9760 guest) dag@ossi.com (Darren Alex Griffiths) writes: > Some of the things I'd be interesting in hearing about include how the > cable is spliced together. I assume that the ship didn't have 3,250 > miles of continuous cable on a big spindle. No, they actually do carry enough cable to do the whole job. Cable is carried in big round holds, but they don't rotate; the cable is pulled out layer by layer from the top, having previously been carefully loaded in port. Splices between sections are done on shipboard when necessary. The cable isn't just dropped overboard; the ship tows a heavy plow that makes a furrow and buries the cable, at least in areas where other ships are likely to be dragging anchors. John Nagle From: floyd@hayes.ims.alaska.edu (Floyd Davidson) Subject: Re: AT&T Ship Sets Trans-Oceanic Cable Installation Record Organization: University of Alaska Institute of Marine Science Date: Mon, 11 May 1992 01:47:06 GMT In article <telecom12.378.10@eecs.nwu.edu> dag@ossi.com (Darren Alex Griffiths) writes: > questions. If someone in the know can spend some time letting us know > more details about the techniques used to lay trans-oceanic cables, or > point to a good reference source, I'd appreciate it. > Some of the things I'd be interesting in hearing about include how the > cable is spliced together. I assume that the ship didn't have 3,250 > miles of continuous cable on a big spindle. Does another ship provide > additional cable every mile or so? How do they lay a cable part way? > I assume that if it's half way across the Pacific they don't simply > let it drop to the bottom and hope they find it again. Is it anchored > to a buoy? Finally, what if the cable develops problems; can they go > down and fix it and is the topology of the ocean floor and the depth a > serious concern? I know just a little bit. I've seen sample pieces of the North Pacifc Fiber. The topology is of considerble importance, and the differences in types of cable are good indicators. Some of the cable is as small as about 1 inch in diameter (most of which is sheathing for protec- tion). It gets larger and larger depending on how much armor is added! There are five or six different sizes in use. At the point where it comes on shore it is about five inches, and the added part is almost all steel armor. That portion is also buried. The North Pacific Fiber is presently being repaired due to problems just off the Oregon coast. I could guess at various ways they might locate the cable, but I really don't know what they do to find it. I do know that it is located and hauled up very quickly. My understanding of the current situation is that it is up on three buoys, they have replaced one repeater and spliced in some new cable ... and it was supposed to go on line Friday night but it did not pass a 24 hour bit error rate test. Floyd From: nagle@netcom.com (John Nagle) Subject: Re: Britain-Japan Fiber Cable Organization: NETCOM On-line Communication Services (408 261-4700 guest) Date: Thu, 29 Dec 1994 17:40:03 GMT wrf@ecse.rpi.edu (Wm. Randolph U Franklin) writes: > AT&T will build a cable from Britain to Japan for $1.2G. It'll be > 17,000 miles long, 5Gbps, and carry 320,000 "voice and other messages". > That looks like only 16Kbps per circuit (which looks low). The > current longest cable is a 9,000 mile one from France to Singapore, > completed a year ago. > Fun math: That works out to a capital cost per circuit of only $3750. > Assume that a phone call from Britain to Japan costs $2/minute. If > all 320,000 channels were in continuous use, then the cable would be > paid for in the first 31 hours. > Alternatively, if we assumed that the cable is good for ten years, > or 100,000 hours, then amortizing the capital cost would be three > cents per hour, or $5e-4/minute. This is a factor of 4,000 less > than the price of the call. The numbers for the newer transantlatic cables look like that, too. You really should be able to buy a full-time transatlantic circuit for about $100/month, and at the rate cable is being laid, you probably soon will. Not having to acquire property rights is a big win. Fortunately, the UN didn't think of this for the Law of the Sea conference. John Nagle |
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