[http://www.digitalmediaasia.com/default.asp?ArticleID=20563]Consortium]( [url) to build US-China cableWhoda thunkit?
What I find more amazing than this is that the manufacture and laying of undersea cables began in 1850 (with experimental versions going back a few decades further) - way before the advent of modern synthetic plastics - they used materials like canvas, natural latex and tar to sheath the conductors, which by today’s standards, would probably seem terribly risky.
Satellites are not that good for real-time communication. It takes the better part of a second for the signal to get up there and back.
It’s fine for one-way stuff, like a TV signal, or GPS, or applications where transmission can be buffered and deferred, like those neat UPS scanners. But talking on a phone on a satellite connection is a drag.
Optical fibres also have far more bandwidth than satellites.
And let’s not forget that much of the Internet traffic is real-time (web browsing, IM, VOIP, etc).
It’s also a hell of a lot harder to tap a fiber line than it is to casually eavesdrop on a satellite link.
Being under the ocean makes the fiber doubly difficult to intercept.
Satellite phone calls are horrid. I’ve got one friend who’s on a very remote island, and I’d rather pay the 90p/min through my normal operator to talk in realtime than the 15p/min offers through third-party telecom companies who use satellite links.
Here is an article from Wired, written by Neal Stephenson of Cryptonomicon* fame, about the history and development of undersea cabling. It’s a fascinating and entertaining read. There’s a printed format option on the page I’ve linked - it’s 56 pages of HTM otherwise.
Highly, highly recommended.
If you play online games, a satellite internet connection will get you killed a lot, unless the server kicks you off first.
No cites, but I understand that solar maxima (the peaks in solar activity every 11 years) can be scary times for satellite operators. Probably useful to have a backup means of communication in case some solar maximum really gets unusually ugly.
I’ve always wondered about these things. How deep are they?
Heh, I (and a quarter million other customers in PR alone) became acutely conscious of the use of the undersea cables 3 Sundays back, when the ARCOS cable loop in the Caribbean region got cut in TWO points on opposite sides, thus leaving a piece unconnected from either direction (It had a cut about a week before off the Honduras/Nicaragua coast from someone anchoring where they should have not; on the later Sunday, it got another cut off Northern Hispaniola). Myself I lost both PRTC DSL and Cingular phone links off-island for about 16 hours until they could get themselves rerouted (there are 3 major cables we connect to).
All the way to the bottom.
The semiannual solar conjunctions are bad enough, messing with all satellite links for a few minutes twice a year when the earth station, the satellite and the sun are all lined up in a straight line.
There’s lots of cables down there, and projects for more cables each year. A cable can carry a lot more bandwidth than a satellite, carry the signal along a much shorter path (eliminating lag), and have a lot fewer things that can go wrong with them. If something does go wrong, a cable is a hell of a lot easier to go fix than a satellite.
Another interesting thing: while the fibers that carry the signal are each about as big as a hair, they’re wrapped in so many layers of metal, rubber and plastic that the final cable is about as big across as a grapefruit. Even the best quality fiber can only carry a signal for about 30 miles, so repeaters have to be placed every so often to clean-up and re-amplify the signal. The ones for the bottom of the ocean are in sealed metal casings about six feet long, about two feet across, and freaking heavy.
The cables rest on the sea floor (or get buried near the coastline if there’s danger of damage from passing ships and trawlers), and a lot of the initial planning involves mapping out the route it has to take, including getting permission from any country whose territorial waters it passes through, avoiding high traffic areas and not crossing over previously laid cables. Twisting and pinching can damage the fiber, so the cable needs to go straight up and down slopes as much as possible, but also can’t go through any sharp bends. If the signal gets cut off, it’s easy to check where the break is by pinging each of the repeaters. They then send a ship out to that point, snag the cable using sonar and a hook, then pull it up to do the repairs and lower it down again when they’re done.
I mentioned my name is reference to undersea fiber optics, didn’t I?
Ages ago, I taught ESL to German engineers who were designing these fiber-optic cables for undersea.
They told me they were far more reliable, faster than satellite connections, easier to repair and cheaper in the long run.
These guys were pretty intelligent and had done their homework, so I was inclined to believe them.
Oh - these were the same guys who designed the wire-guided, undersea missles that they knew were outdated, but sold to third-world countries anyway.
They will run across the ocean floors, which is deep enough (much of it in the range of 4-5 KM down), but not to the extreme depths of the trenches.* In oceanographic terms they’re benthic, not abyssal.
- Yeah, we all know already when and for how many minutes someone was at the bottom of the Marianas Trench. So anyone posting it is liable to being shot with a 1920s style death ray, and then burning his dog.
How are the repeaters powered?