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New Tech Lets Submarines 'Email' Planes (bbc.com)
A way for submerged submarines to communicate with planes has been developed by researchers at MIT. From a report: At present, it is difficult for planes to pick up underwater sonar signals because they reflect off the water's surface and rarely break through. The researchers found an extremely high-frequency radar could detect tiny ripples in water, created by an ordinary underwater speaker. This could let lost flight recorders and submarines communicate with planes. Submarines communicate using sonar waves, which travel well underwater but struggle to break through the surface. Planes communicate using radio signals that do not travel well in water. At present, submarines can surface to send messages - but this risks revealing their location. Sometimes, buoys are used to receive sonar signals and translate them into radio signals. "Trying to cross the air-water boundary with wireless signals has been an obstacle," said Fadel Adib, from the MIT Media Lab. The system developed at MIT uses an underwater speaker to aim sonar signals directly at the water's surface, creating tiny ripples only a few micrometres in height. These ripples can be detected by high-frequency radar above the water and decoded back into messages.
The researchers found an extremely high-frequency radar could detect tiny ripples in water, created by an ordinary underwater speaker.
Umm, couldn't an adversary use the same tech to detect the larger ripples (albeit not targeted) generated by the sub displacing water as it moves?
I thought this was the purpose of HAARP?? (I kid; nobody actually believed that...)
The whole point of being underwater is to not reveal your position. A buoy that's directly above you is an absolute giveaway. But these signals could probably not be detected without already knowing their position.
New sub, who dis?
;)
Anons need not reply. Questions end with a question mark.
You are assuming this would only be used for military/covert comms. Based on the overview alone, I could see this being useful for tons of stuff. Non-mil submarines that don't have Bouys; Situations where bouys or surfacing is a waste of time. unmanned sub status communications. black boxes. emergency/crash comms.
FTA: "it does not work when there are waves taller than 16cm (6in) in the water." Doesn't most of the ocean have waves higher than 6 inches?
Either the sub crew is reciting Beowulf in pig-latin or the prawns are farting.
rewriting history since 2109
Or the plane could drop a sonar buoy like they have been doing for more than half a century
It doesn't. The plane flies a predetermined route. If the sub has anything to say it needs to be close enough to that route and send its message at the time the plane will be overhead.
Geez, and my crummy ISP only lets me do 10mb of attachments.
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The whole point of being underwater is to not reveal your position. A buoy that's directly above you is an absolute giveaway. But these signals could probably not be detected without already knowing their position.
Most of the time the "folks back home" will know the sub's route and communication rendezvous (which may or may not all be kept) so knowing where to look/listen is usually not a problem. And communication aircraft can fly lots of bogus tracks so that that does not give it away.
An antenna buoy is pretty easy to spot, if an observation platform in in sight of it. So you don't use these when that is likely (subs have a number of alternate methods of communication). But my concern is whether this acoustic signal can be detected by a sonobuoy or other hydrophone platform. Being acoustically quiet is what a submarine is all about. Most subs never uses its active sonar, ever (although it has one, just in case).
Second class citizen of the New Gilded Age
You must have lots of mines since an airplane can fly hundreds of fake track miles.
As you say - "genious" (sic).
Second class citizen of the New Gilded Age
At present, it is difficult for planes to pick up underwater sonar signals because they reflect off the water's surface and rarely break through. The researchers found an extremely high-frequency radar could detect tiny ripples in water, created by an ordinary underwater speaker. This could let lost flight recorders and submarines communicate with planes.
In all the stories about MH370, I never understood why it was apparently so difficult to locate the flight recorder. Now, finally, in a story that has absolutely nothing to do with MH370, I understand.
I'm glad I now know, but sure would have been nice if at least one of the many MH370 stories had actually explained this.
The real solution (one that I think is already being used) - is quantum entangled communication.
The problem with quantum entangled communication is that it requires cold fusion reactors to power it. Otherwise it doesn't have enough energy to travel through the ether.
There is one fact that reduces the usefulness of this as a military communications channel that I haven't seen mentioned by anyone else. As far as I know, subs communicate with higher authority using VLF, ELF and SLF frequencies. The way it would work is that the sub would tow a very long antenna behind it while on cruise in order to communicate with the base station(s), which in turn routed the signals to the land based submarine command facility and the joint chiefs communication facility. From there, it could be further routed by conventional radio or satellite to naval or aviation assets in the area of operations.
They are low-bandwidth frequencies of course, but you can transmit a hell of a lot of information using pre-generated code phrase books/databases to cover most contingencies.Those of use who deal with passwords and IT security are well aware of how quickly the number of possible alphanumeric character combinations goes up as you add successive characters to a required length. (for those of us who don't know: an 8 character string has 218,340,105,584,896 possible combinations so you could have that many code phrases in a database)
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There's a reason subs are sea-gapped.
And quantum entanglement is SUPPOSED to be incapable of transmitting information.
Take off every 'sig' !!
Submarines already have towed floating antenna arrays which are capable of communicating with satellites which can then relay messages to planes all over the globe. They also have towed sonar arrays, towed optics arrays to communicate digitally with light.
Looks like some of these MIT boys n' girls should have joined the Navy before inventing solutions to things which don't have a problem.
Let's make like a bird... and get the flock outta here.
High frequency audio under water can be easily beamed, and dissipates fairly rapidly with distance. A submarine 200 feet down beams ultrasound at the surface, the ripples from which are detected by an airplane overhead. An enemy attempting to listen ten miles away may be 40 dB down in the beam pattern, 30 dB down from the ratio of distances, and 60 dB down from attenuation through the water (numbers hypothetical). Total 130 dB down, maybe undetectable.
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Sonar from whales you hear 100ds of miles under water, and their singing even farer.
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detect tiny ripples in water, created by an ordinary underwater speaker. This could let lost flight recorders and submarines communicate with planes.
Chances are this underwater speaker would have to be quite "loud," and connected to a powerful amplifier that would quickly drain the battery in a flight recorder.
That that is is that that that that is not is not.
Did they do this in a calm, still pool, or did they do this in the noisy, wavy ocean? If it was in a pool, get a dozen kids playing "Marco Polo" and see if it still works.