The sharks want their LASERs!
Re: "the shark-bite problem is specific to optical fibre cables rather than their retired copper predecessors"
The world's submarine cables are subject to a brand-new threat: sharks. As detailed in this article in the New York Times, shark bites emerged as an increasing problem in a new cable crossing the Atlantic, causing four segments of the cable to fail. As AT&T points out, the shark-bite problem is specific to optical fibre …
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I've been in this buisness since 1999, so let me share some info, as I was a trainer.
Kevlar is sexy, but unusable for these cables. It is used in terrestrial cables for its _tensile_ strength. Meaning you can pull on it with little damage. When it comes to submarine cables, you have bending, pinching and grounding problems (for the outer conductor=armouring). The first two deal about mechanics, so kevlar does not have the required rigidity. The last one deals with... sharks !
An electrical current flows through the cable in what's called the "inner conductor". This is to power the "repeaters" (optical amplifiers every 75km). The current is DC, around 1A, but sometimes high voltage (up to 12 kV on several thousands km). Sharks never can "sense" DC voltage.
Sharks have the "Lorenzini organs" : it senses AC electrical fields, such as the ones going through nerves or muscles of their preys. Normally, there is no AC in submarine cables.
I said _Normally_. In case of cable break, an AC voltage is fed into the cable so the cable ship can spot the cable break on the seabed using an electromagnetic sensor. Around the break (no more shielding) the sharks feel this 37.5 Hz wave (wounded fish is around 30-35 Hz).
But, then... who cares if they bite the cable, as the cable is _already_ broken there ?
Just the Google idiots, who don't know about this business. I trained some of them on this technology. They talked about AI, but never showed any NI (natural intelligence).
On one hand, it's poor journalism. On the other hand, it's just part of the PR clout of Google that they can get old news touted as technical wonders or have these breakthroughs attributed to them rather than those actually doing the work. (Whether they actively try to or not.)
Apple have similar PR wizardry with scores of journalists swooning over the most elementary changes.
The rise of Internet 'journalism' has put pressure on more traditional outlets to publish information as quickly as possible. In many cases, this leads to stories that are little more than regurgitations of press releases. We see it in politics as well as general business news but ever more so in 'tech' news.
In some ways, it can be seen as 'you get what you pay for'. People are not buying newspapers and don't want to pay for online subscriptions so newspapers don't have the money to hire as many journalists or do as much research or investigation. Whatever fills the paper quickest wins. On the other hand, we put the chicken before the egg and we can see that the move to getting our news from other sources is a reaction to the decrease in quality of the reporting.
The real problem is that companies and political parties now have an expectation that their words will be repeated verbatim and their messages broadcast to the public without question or criticism. Perhaps less so in the US where there is a greater breadth of news outlets, but certainly in Australia it is a toxic, closed, society of journalists willing to tow the line, and thus continue to receive the table scraps from the spin doctors while those willing to dig deeper and call out the bullshit are forever on the outer.
It's one thing the AFL (for example) have been called out on as they only give stories and interviews to those journalists willing to tell the AFL's version of events. This came out strongly in the recent (and on-going) doping saga as many journalists came forward saying that they were cut-off when they criticised the AFL or ran pieces that contradicted the official story.
Rant much . . .
@dan1980
The US is no better off than Australia in this regard. We simply have more breathlessly excited reports of discoveries of basic phenomena and learned proposals for perpetual motion that you. Between this, competition for privately funded research, and an education system that believes superficial knowledge of the latest buzz phrases is more important than fundamental understanding, the integrity of US science is at an all time low.
Even the patent office--being "customer-funded" by processing fees--has been infected. In the past few years I have seen patents for radar (exactly as the Brits invented at the start of WWII); Kirchoff's law (as "invented" in 1984), and a "scalable system"l to extract "unlimited power from any point in the universe" based on a fundamental misunderstanding of the difference between energy and power."
I also attended a conference where one of the presenters trotted out a brilliant new invention for transmitting electrical power through wall, thus eliminating wires in buildings. The invention: an air core transformer, known since the late 1800's. .
These and countless other wonders are routinely trotted out as "news." The same old ideas are also routinely trotted out under new rubrics and patented. Courts, ill equipped to deal with esoteric technical matters, and reluctant to seek independent expertise, then grant injunctions against companies doing legitimate business.
Horse shit.
I was the Engineer in charge of investigating this exact problem between the Philippines, New Guinea, and Australia. E-1 (2.048 Mbps) lines. In 1985. Seems the sharks picked up on the electricity in the cable & wondered if it was edible ... We adjusted capacitance & inductance, and the problem went away.
Hmm, 1985. Was that a Cable & Wireless cable?
C&W had for a while one of the best cable laying fleets, but I think they sold that off around the 90s (been a while). It was rather interesting to visit such a ship, and to see how thick the cable ended up with all the armour.
I've got a genuine chunk of used PTAT-1 (http://en.wikipedia.org/wiki/PTAT-1) cable at home. About 18inches that I sawed off the end of one of the branching units when it got hauled back up for the repair of an intermittent fault. Wiped out three hacksaw blades doing it - the high tensile steel in the middle is tough stuff! Doesn't look like it would ever bend but, yes, once you've been to the factory you can see it does...
"I was the Engineer in charge of..."
Of course you were jake, that was quite a while after you were the 4th member of the crew of Apollo 11. Didn't I read that you the one holding the camera to take pictures of Neil Armstrong coming out of the Eagle? History was cruel not to have correctly recorded you as the first man on the moon, but you can tell us all about it here.
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I worked on the development of the first optical fibre cables from 1980s onwards and this problem first showed up on an ATT trial off Gran Canary (around 1983) when they had left off the Glover Barrier - i.e. the cable was no longer screened. The AC ripple on the 20kV DC power feed attracted one species of shark that hunts fish by detecting the electric fields generated as they swim or struggle if they are in distress.
So very easy to fix - ATT replaced the Glover Barrier and the ripple is screened - and then the sharks ignore the cable. Fortunately the UK companies did not make the same mistake!
AND BTW cables are only ever armoured is shallow water when they cannot be buried - and when they are subject to anchors, fishing trawls, and worse - tidal abrasion on rocks. In deep water the cables either lay on the sea bed or form catenaries spanning undersea mountains, ridges.
and canyons.
Sadly, we live in a world of growing data and rapidly rising ignorance!
Peter Cochrane
It isn't so much rising ignorance as rising amount of information making it easier to be ignorant of a great portion of it. Even (most of) us "smart" people who read The Reg may be very knowledgeable in technical fields but may be woefully ignorant in others.
It is difficult to imagine a true renaissance man like Leonardo Da Vinci who can make significant contributions in many disparate fields being possible in our modern world.
The problem isn't rising ignorance - infact I would put money on the fact that ignorance is waning
The real problem is that the ignorant have so many outlets (Twitter, Facebook, BBC Chav your say, El Reg Comment boards) these days to make themselves heard. 20 years ago their idiotic ideas would have been limited to Colleagues, family and boozer with only the spectacularly thick making their way to day time TV in order to entertain the slightly less dense and students.
"I worked on the development of the first optical fibre cables from 1980s onwards and this problem first showed up on an ATT trial off Gran Canary (around 1983) when they had left off the Glover Barrier - i.e. the cable was no longer screened. "
I'm pretty sure when I read the Cable and Wireless Centennial tome (published about 1958) that they had similar problems with sharks chewing on telegraph cables back in the days when it was the Gutta Percha Rubber company(*) and before Lord Kelvin made his fortune working with them.(**)
The book didn't go into any detail about how the issue was solved, other than "armouring the cable".
(*) Which shows that Nokia isn't the first hi tech company to come from rubbermaking - by about 100 years.
(**) He worked out how to lay submarine cables without breaking them and it made him a billionaire overnight.
"Shark dentist?" Could he be any more condescending?
And how the hell is there an electrical current in fibre optic lines? I'd expect the reverse, where the electric current from the copper cable keeps the sharks away, and the lack of it around fibre optic means they can go "hm. different. wonder what it tastes like?"
Unless the tech has changed, isn't there an electrical supply alongside the fibre to power the fibre optic amps/repeaters at stages underwater? Or is end to end with no repeaters now possible?
If there is any power then the question is only, AC or DC? AC would be the one that attracts sharks.
You can change the effective inductance and capacitance of a cable by altering the loading at the ends - that's how loading coils work on antennae, to change their effective 'length' - only in the real world such a massive cable would probably be impossible to tune in this way.
Kevlar, or something similar to Kevlar? There seems to be varying reports.
http://www.independent.co.uk/life-style/gadgets-and-tech/news/google-using-superstrong-material-to-protect-underwater-internet-cables-against-shark-attacks-9671177.html
"The fibre optic lines under the Pacific are being wrapped in a super-hard material similar to Kevlar, which is used to make bullet-proof vests and military armour."
My understanding from my friends in law enforcement is that because it was a woven fabric, Kevlar was not particularly effective against knives. Just confirmed this. Googling "stab vests" is informative.
Bottom line is that it takes a lot of layers and special fabric design to do the job with just Kevlar.
One hopes that Google has had the foresight to thoroughly test their "new" Kevlar design with real sharks before they deploy thousands of miles of it.
Kevlar vests are woven for flexibility. Kevlar sheathing is an entirely different beast.
At one point some makers were selling kevlar Bull Bars - these were sold, transparent things about 1/10 the weight of the steel ones and just as non-fun to walk into.
Power feeding is the answer you are looking for.
There are optical amplifiers fitted to each fibre every 60~70km which require DC power to operate (50V per amplifier), so a positive voltage is fed from one end and negative from the other - a long cable may have 25kV or more applied across its ends. The power is carried by the copper tube surrounding the fibres. This tube is interrupted at each amplifier with 50V being dropped across each of the series connected amps - kind of like xmas tree lights.
One of the interesting side effects of this is that somewhere near the mid-point of the cable the voltage on the power conductor is zero relative to the seawater outside the cable. This means that if a shark or other agency does expose the conductor to sea it is sometimes possible to move the zero volts point by adjusting the power feeding voltage at each end. This stops (or minimizes) current leakage at the fault point, allows the cable to keep working until a repair ship is on-site and reduces galvanic erosion of the copper tube at the fault point, which can ruin km of otherwise good cable in fairly short order.
Unamplified (hence no power feed) cables are possible - personally I've worked on one of 235km - but require the use of Raman pumps at the end points and are likely to have capacity restrictions due to signal to noise compromises imposed by the lack of intermediate amplification. My understanding is that the maximum length for this type of installation is under 400km.
Sorry, no I wasn't there on the Apollo mission - just work for a company that does submarine cables amongst other things.
I worked on the development of the first optical fibre cables from 1980s onwards and this problem first showed up on an ATT trial off Gran Canary (around 1983) when they had left off the Glover Barrier - i.e. the cable was no longer screened. The AC ripple on the 20kV DC power feed attracted one species of shark that hunts fish by detecting the electric fields generated as they swim or struggle if they are in distress.
So very easy to fix - replace the Glover Barrier and the ripple is screen - and then the sharks ignore the cable. AND BTW cables are only ever armoured is shallow water when they cannot be buried - and when they are subject to anchors, fishing trawls, and worse - tidal abrasion on rocks. In deep water the cables either lay on the sea bed or form catenaries spanning undersea mountains, ridges.
and canyons.
Sadly, we live in a world of growing data and rapidly rising ignorance!
Peter Cochrane