Submarine cable network of use to Sydney scientist.
Scientists have called for telecommunications companies to open up their old and new submarine cables to climate change research.
According to Sydney University scientist John Yuzhu You, undersea cables could be used to monitor currents, salinity, seismology and ocean temperatures.
As water moved around a cable, it generated an electromagnetic current that could be measured by voltmeters at cable landing stations, You explained.
Voltmeters would cost up to $3,000 to set up, he said, and because fibre optic cables could remain under the sea for decades, they could be a consistent, continual source of data for researchers.
“Only a tiny fraction of the existing undersea cabling is used for scientific purposes … this is a missed opportunity,” You said.
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At first I thought this might be silly, since you can’t generate or detect voltage in a glass fiber but then I had a look at this diagram:
1 – Polyethylene
2 – Mylar tape
3 – Stranded steel wires
4 – Aluminium water barrier
5 – Polycarbonate
6 – Copper or aluminium tube
7 – Petroleum jelly
8 – Optical fibers
I assume then he’s talking about putting a voltmeter on either the copper/aluminum jackets.
Interesting idea. Full story here
The drawing may be missing a couple things. It may not be an issue with optical fibers, at least if the run is short enough, but copper cables certainly need repeaters to boost the signal, and that requires power lines to power the amplifier/signal regenerators.
Looking at the voltage and current flow could provide information about temperature (due to resistance changes in the wire) and inductive effects.
I’ve long since forgotten how far an optical fiber can transmit a signal before it needs a repeater. For some low bandwidth signals it can be a long way.
That reminds me of Abbott and Costello…
– … cable landing stations, You explained.
– I did not explained this…
– … this is a missed opportunity,” You said.
– No I did not say this… who did!
– Who? You?
– You! Who?
This is a great idea and I hope something comes of it. In reality we know less about the oceans than just about anything else and when it comes to understanding climate related matters, the oceans are probably more important then the atmosphere. The best part is, those cables stay put for a very long time.
Yes, that is an interesting idea.
But many technicalities pop up in your mind. Would be interesting how they overcome them. One, how to differentiate from geomagnetic field fluxes which could also generate currents or potentials. Two, seems the old internal wires as seen in the lead picture would have mutual cross-potentials generated. Three, water flowing generates enough potential (therefore possible current) to measure and differentiate exactly what velocity and in what direction the water is moving? Seems the telephone companies would have noticed this voltage years ago and could prevent a possible hopeless dump of cash if this effect doesn’t really exist.
Sorry to be skeptical but monitor all of currents, salinity, seismology and ocean temperatures from a reading of water current generated voltage? Sounds more like a cry for an immediate cash influx and cushy long term job for many buddies. I thought ARGO and the tsunami detection and warning system already had all of those jobs.
Are those cables not ploughed into the seabed for protection? So anchors and trawler nets won’t catch on them? On land, fiber cables are nowadays laid in protective PE or PP tubes as they are rather sensitive to bending etc.
HEre some warmista insinuating that you basically have to lie to make believe
http://www.npr.org/templates/story/story.php?storyId=129125389
No the cables are not buried down deep and nets do get caught on them. This was something the US Navy took advantage of during the cold war and tapped the Soviets undersea phone cables. To read on how this was done pick up the book “Blindman’s Bluff”
http://www.amazon.com/Blind-Mans-Bluff-Submarine-Espionage/dp/006097771X/ref=sr_1_3?s=books&ie=UTF8&qid=1281769024&sr=1-3#_
In shallow water (continental shelves) the cables are sometimes partly buried, for the reasons you cite. Environmentalists don’t like that; it disturbs the pristine sea bed..
In deep water, no.
Bending and damage issues are the reason for all the layers in the deep-sea cable. It’s even worse with the copper ones, where the center, the actual conductors, can be up to eight or ten centimeters in diameter. Some of the later copper cables, before fiber started being used, were eight inches (twenty centimeters) in diameter. Remember that the cable has to support its own weight from the ship to the sea floor while it’s being laid.
On land, the polypropylene or polyethylene tubing used for protection is also used for renewal — when a cable becomes inadequate, they pull a new one through; much cheaper than laying from scratch. I don’t know of anyone doing that at sea.
In general, undersea fiber optic cables are plowed into the seabed from shore to about 1500 feet depth. Then they lie on the seabed.
They also require a repeater just like the old undersea copper telecom cables. Fiber optic repeaters take power from from several of the metal foil/armour layers within the cable jacket. The repeaters are typically located about 60 – 100km apart on land, it may be closer undersea. Btw… it is by these repeaters that all undersea cables are tapped by the US government and others. A large over shell is mounted over the repeater section of the cable and can sense and record the electrical noise of the repeater circuits in essence acting as something like a packet sniffer.
Fiber optic glass core is currently used as a thermometer in the oil & gas industry and as a microphone to sense fatigue in structures.
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Wayne: Yes, they did. Around the 1850’s in fact by a gentleman called William Thompson, later Lord Kelvin who did a lot of work on this and created the mirror galvanometer to find signal in the noise. Newer cables have already detected geomagnetic effects from earthquakes and old cables are already being recycled for this.
The cables already have voltmeters attached given the copper tube is usually the power core carrying 10kV DC or more at around 1A to power the repeaters and branching units along the cable. The Power Feed Equipment (PFE) needs to provide stable power along the system so usually monitors the power characteristics pretty tightly.
Some of the rest sounds like wanting to modify the repeaters aka torpedoes, and this is a great quote:
“but manufacturers would first need to invest “a couple of million dollars” on redesigning the devices to include appropriate sensors, You said.”
Errm. Right. Who’s going to pay for that? There’s also a boring little problem of structural strength. When I worked for a submarine cable company, I was puzzled why such expensive cables had so few fibres in them. Problem is the repeaters need to house the electronics to regen each fibre, so more fibres, more kit and more weight to attach to the cable. That’s one of the design challenges with extending distances between repeaters.
Existing cables are generally laid to be protected from currents and stop them drifting. That’s both to protect against damage and stress, and also protect from shipping and fishing. If the cable drifts outside the marked protection zone, the cable gets more vulnerable to damage. A big anchor dropping near a cable can break it. That may be why the scientists want to move the cables to more interesting locations, but it’s not that easy and they may end up with a lot more maintenance. One potential problem with that is the decline in bandwidth costs had a knock on effect on the people operating cable laying and maintenance ships which are specialised and in demand.
Soren: Submarine cables are generally only protected when they run shallow given the cost and complexity of doing that. That might be direct burial, or more complex protection using matresses and concrete where there’s a lot of shipping or fishing traffic.
For UK folks thinking of holidaying in Cornwall, this is a fascinating place to visit
http://www.porthcurno-telegraph-museum.org.uk/index.php
[reply] Don’t bother with the pub though, head round to St Just for dinner. RT-mod
Soren says:
August 13, 2010 at 10:53 pm
“Are those cables not ploughed into the seabed for protection? So anchors and trawler nets won’t catch on them?[…]”
No. Occasionally they do get broken by an anchor; a repair ship will then go and locate the breakage and mend it.
As Soren says, I have read and seen films of cables being laid on the sea floor. older cables were paid out from the back of a ship and it was hoped that they were OK. Nowadays the ships have sonar etc to “see” what is going on they use this to stop the cable hanging on things or to go round obstructions, also some have either tethered or remote vehicles to trench the cables into the sea bed. In deeper oceans the cables are left on the sea floor so it might work for these.
RT-mod: You’re right about St. Just – my part of the world – let me know if you’re coming again, I’ll buy you a drink or three. Dave.
It’s true that in deep water the cables aren’t trenched into the sea bed. However, much of that sea bed is ooze, mud or sediments into which cables tend to sink (or which is deposited on top of them). So much of the cable will not be exposed to moving water. How much was exposed would be very difficult to determine. Worse, the amount exposed would keep changing, as the currents shifted sediments around. I find it hard to believe that one could get much reliable scientific data this way, at least without a great deal of effort and expense, and some heroic and questionable manipulations of the raw readings. Purpose-built probes would be better and cheaper in the long run (I’m thinking dart to stick into the mud, body light enough not to sink into mud, wire running back up to surface float for communication).
Questions for any undersea cable engineers in the audience (either direct answers or links to them): How do the cables physically behave as they traverse the mid-ocean ridges? E.g., do they follow down the canyon slopes into the the actual spreading centers; do they hang as catenaries over long stretches of valleys; how do they handle lava extrusions in their neighborhoods; is there enough give in the cable to handle the few centimeters per year of separation?
Thanks in advance, OUH
Paul, I could probably get some models made that would give you the data you wanted. Do you know anyone who is good at writing up grant proposals?
OldUnixHead
Good article here on submarine cables and the “Slack Control Wizards of Chelmsford”
http://www.wired.com/wired/archive/4.12/ffglass.html
and I was lucky enough to work for the company that built that cable, although on the services side. It’s a strange world with a lot of different challenges to normal telecomms. Generally I think the aim when the routes are surveyed is to avoid caternary segments and any sharp or rough edges to prevent stress or abrasion on the cables. That’s where the art of slack management comes in though. The cables need enough give/slack in them so they can be lifted to the surface and repaired if needs be, again without putting too much strain on the cable. I used to think that was done with ROV’s, but then I got shown the cutting and grappling hooks 🙂
Paul Birch: I was on the receiving end of a couple of academic proposals, one asking for the donation of a pair of fibres on a system so they could ‘experiment’. One involved doing the biggest/longest file transfer to claim a record and they seemed a bit put out when we told them we’d done that already. And the world’s longest Ethernet, rack-rack in London via Tokyo, just to see what would happen. Some of the other suggestions were more interesting, but a few snags with playing on a production network and an unwilligness to share IP on anything developed stopped those.
“and an unwilligness to share IP on anything developed stopped those.”
And that is a major issue seen all over the place. People want to use other people’s resources to investigate things but are unwilling to share any results (Intellectual Property). It is interesting to me how knowledge has become “property”. Often an academic doesn’t want commercial use made of their discovery or some university wants to claim ownership and want to only allow it to be used under license, even to the company whose resources were used in the research. So it is no surprise that there isn’t more of this sort of cooperation between industry and academia.
Academia tends to be anti “corporation” so the idea of cooperating with one and allowing it to profit from the research drives them batty.
And the same works in reverse, sometimes the company does not want to disclose something if it is major and give it an edge. There needs to be a way to resolve that conflict of interests somehow.
A lot of comments, a lot of good info regarding submarine telco cables.
There is, perhaps, some distortion or incompleteness, in the same vein as the proverbial blind men describing an elephant. Not all sea floors are the same, so not all installations are the same. Shallow crossings might be plowed (that’s ‘ploughed’, for the good Brits), but any depth at all and cables are just dropped to the bottom. Even the Mississippi River crossing at Baton Rouge, LA, was too deep to consider plowing (wrt the old copper cables; fiber optic cables are attached to the bridges). Despite warning signs, sometimes a ship would drag its anchor along the floor and snag a cable, ripping it right out of the splices in the manholes at the river’s edge.
If a sea floor is soft, copper cables might sink a little, or be covered with silt. This doesn’t happen much with fiber cable because it is substantially lighter, and I think that may cause a problem with the proposed research.
There is a story about the initial testing of fiber optic submarine cable which is interesting. The first tests were in the Canary Island area, I believe. Cables were put down, and tests run. Not long after the start of testing, one of the cables went bad. It was pulled up, examined, and it had a considerable number of tooth marks in it – sharks. It was deemed just an anomaly, repaired, and restored for testing. But it happened again, and with other test cables. The ivory community came up with a number of esoteric theories, and the general consensus was that the sharks were attracted to the weak electromagnetic field produced by the cables (yes, the regens need power, and the cables have conductors in them for that). Further testing proved that to be wrong. It was finally determined that the cables were so light, that they did not hug the floor. The floor in that region is rugged, and sometimes the cables would span over the area between two higher areas on the floor. Currents caused these spans to sway up and down – the same movement as an eel would make when swimming. I imagine the sharks thought (if they could think) that the cables were the longest damn eels they had ever seen. The problem was solved by adding additional weight to the cable, and making sure there was plenty of slack, so the cables would sit on the floor.
Still, there are areas where the cable must span deep crevasses and oceanic trenches, and it is reasonable to assume that currents may cause it to sway vertically. How would this motion impact the data if the cable was used as proposed in this article?
wayne says:
August 13, 2010 at 10:43 pm
Yes, that is an interesting idea.
[–snip for brevity–]Sorry to be skeptical but monitor all of currents, salinity, seismology and ocean temperatures from a reading of water current generated voltage? Sounds more like a cry for an immediate cash influx and cushy long term job for many buddies. I thought ARGO and the tsunami detection and warning system already had all of those jobs.
That’s exactly my set of thoughts as well. They talk about ‘climate change,’ but in reality its all about a whole slew of other effects which they seemingly don’t want to mention.
It´s a great idea. It will surely reveal surprising data. No wonder that many will oppose it.
I smell a government grant!
My expertise is in electro-optics and I worked for the company that installed almost 50% of the submarine telecommunications cables in the world.
The first successful submarine TELEGRAPH cable was built in 1865 in our factory at Greenwich, UK by Cyrus Field (US entrepreneur). His chief engineer was C.F. Varley who employed William Thompson (Lord Kelvin) as a consultant. Varley and Thompson made personal fortunes out of their collaboration but Field went broke. The cable was built in one continuous length, stored in 14 cylindrical tanks, each of 500 cubic meters capacity. These tanks were flooded with water chilled to 4 degrees Centigrade for testing. The tanks still exist and I used them for growing rainbow trout until 1982. The only ship large enough to carry the entire cable was the “Great Eastern” designed by I.K.Brunel.
The 1865 cable was eerily similar to TAT-8, the first optical fiber transatlantic cable. This cable was armored to almost 4″ diameter for the parts that were laid on the continental shelves (<400 feet depth). For most of the distance the cable was not armored so the diameter was less than 2". The cable was (and is) of the coaxial type.
Gutta percha insulation has been replaced by polyethylene. The jacket is also polyethylene but the conductors are still made of copper. The armoring on the shallow water parts has not changed in 150 years (zinc coated steel). However we now have submersibles (underwater "Ditch Witches") that can bury the cables in areas where anchors may be deployed. Unfortunately, we can't bury them deep enough to resist the anchors from really large vessels (e.g. super tankers).
Although the first transatlantic cable (TAT-8, 1988) is a coaxial cable, its central copper conductor is hollow to accommodate 6 optical fibers. Regenerators are installed at intervals of ~80 km which means there are a total of 60 between the UK and the USA. These regenerators are powered by means of the ~1 Ampere current that is fed down the center conductor. The total "end to end" voltage drop is ~20,000 Volts. The system was taken out of service in 2002, so it may be available for other purposes.
Prior to the introduction of fiber optics, many more amplifiers were needed. For example, TAT-7 (a copper cable) had over 600 amplifiers.
While the early fiber optic cables (TAT-8,9,10 &11, CANTAT-3) used regenerators, all subsequent cables since TAT12/13 in 1996 have used Erbium Doped Fiber Amplifiers (EDFAs) invented by David Payne at the Southampton University in the UK. These amplifiers had the effect of multiplying the capacity of the optical fibers by a factor of several hundreds.
You might think that the huge increase in capacity made possible by the introduction of EDFAs would be a great blessing. Indeed it is, but it is also the curse that triggered the collapse of huge companies including "Global Crossing" and the restructuring of the entire telecommunications industry in 2000 and 2001.
Responding to some of the points raised in the above posts, submarine cable routes are surveyed very carefully to make sure that cables are not laid across underwater ravines, in places that are subject to strong currents or areas of geologic instability. In spite of our best efforts, most of the cables in the south China sea were severed during an earthquake in 2007. Fortunately a cable to obviate this problem was already on order for linking Nedonna Beach, Oregon to Qingdao, China.
http://atlantic-cable.com/Cables/2008TPE/index.htm
This cable ensured that TV coverage of the Beijing Olympics would be excellent. Owing to the extreme length of the above cable, it has a record number of optical repeaters.
Since TAT-12/13, major intercontinental optical cable systems have been installed as pairs or rings with the idea that the cutting of a cable will only reduce the system capacity by 50%. As Robbie Burns said, "The best-laid schemes o' mice an' men
gang aft agley". As if to prove this, one leg of TAT-14 (USA-GB-FR-NL-D-DK) was cut in November 2003 followed by the cutting of the other leg a week later before it was possible to repair the first cut. The system capacity was equivalent to over 7 million simultaneous phone conversations. Worldwide Internet volume dropped by about 10% until this system was restored.
With regard to using optical fiber cables as sensors, there are networks of military cables (e.g. SOSUS) that use the acoustic sensitivity of optical fiber to detect ships and particularly Russian submarines. While we could use telecommunications cables for this purpose, it would require additional terminal equipment as our existing terminals are carefully designed to eliminate all acoustic interference.
With regard to electric induction effects into the basic (copper) coaxial cable, can anyone tell me how this is supposed to work?
“As water moved around a cable, it generated an electromagnetic current that could be measured by voltmeters at cable landing stations, You explained.”
It’s the Abbot & Costello sketch again.
gallopingcamel says:
August 15, 2010 at 12:04 am
“With regard to electric induction effects into the basic (copper) coaxial cable, can anyone tell me how this is supposed to work?”
I would assume that the intention would be to inject an AC signal and measure the transmitted and reflected waves as the frequency is ramped up from DC to maybe ~300MHz. They might be thinking of something much cruder, though; put a DC current through the cable, generating a magnetic field; motion of the electrically conductive water through that magnetic field in turn generates a voltage in the cable.
jtom says:
August 14, 2010 at 1:24 pm
“If a sea floor is soft, copper cables might sink a little, or be covered with silt. This doesn’t happen much with fiber cable because it is substantially lighter, and I think that may cause a problem with the proposed research.”
If the fibre cable is armoured as in the diagram, or even just with the copper and aluminium inner portions, then its relative density will be ~4 or 5, more than enough to sink into (some of the) silt, or be covered by it. It would only take a few centimeters of covering to affect the signal markedly, unless we are talking very low frequencies. But with low frequencies (long wavelengths) one would be unable to resolve sections in which the amount of cover varied along the cable length on metre scales. This all seems horrendously messy.
crosspatch says:
August 14, 2010 at 12:24 pm
“and an unwilligness to share IP on anything developed stopped those.”
To measure the sea speed, I think what the scientist wants to do is measure the voltage at both ends of the cable. A bit like the Hall effect: Google wikipedia.
A problem that i see is if the cable is 1000 kms long, you can only get the average current across the entire cable. Also, you have to integrate the sea velocity not just next to the cable, but also at a diminishing vertical distance from the cable.
Another problem / challenge i see is geomagnetic currents are quasi-dc currents that could distort the results.
Another problem comes about from DC transmission lines that may have DC currents leaking within the area of measurement of the copper cable. This is a problem: the earth connection to ground has to be large enough to prevent old magnetic compasses on ships giving false magnetic north south readings due to distorted magnetic fields arising from the DC transmissnio line earth connection for monopolar lines.
Another problem I see is that the earth has currents flowing through the magma, will this also distort the results?
Interesting idea still, maybe simplistic?
Looking for a contact for John You, the promoter of the idea. Sydney University does not have his current contact details. Need to understand the parameters under which his scheme will work.