New Tech Lets Submarines 'Email' Planes (bbc.com) 58
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.
Ummm (Score:3)
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?
Re: (Score:2)
Yeah, but as this is analogous to "email" per TFH, I guess the semi-public nature of the communication is perfectly acceptable.
Re: Absolutely correct (Score:3)
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.
Re: (Score:1)
You know, the latest public information about submarine technology is like from the 1970s. What I suspect is that the state of the art is WAY beyond civilian technology. I always thought they would find a way to use gravitational waves to communicate through masses like water and the earth's crust. I bet you could vibrate a bar in the direction of its length, at a very high frequency to send a rather directional gravity wave that could be picked up by a another massive sensor.
Re: (Score:2)
And quantum entanglement is SUPPOSED to be incapable of transmitting information.
Re: (Score:2)
This is a real concern for submarine security, and it limits a submarine's ability to travel fast at shallow depth. Aerial submarine reconnaissance missions do look for this, and it has been of interest for radar satellites.
I think the flight recorder scenario is more a more likely scenario since a submarine can surface an antenna buoy without creating acoustic signals.
I have wondered about whether it would be possible to engineer a back-up flight data recorder buoy that would be released in a crash (possib
Re: (Score:2)
Depends. There's more low-frequency energy than high-frequency energy on the ocean surface, so if the sub motion only generates large slow waves then it may in fact fall below the noise level, even while this high-frequency stuff doesn't.
Meh (Score:1)
Because letting a buoy with an antenna rise up to the surface would be too difficult. Let's analyze micro water ripples in a lab setting instead, it will totally work on the oceans.
Re: (Score:2)
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.
Re: (Score:3)
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.
Re: (Score:2)
You must have lots of mines since an airplane can fly hundreds of fake track miles.
As you say - "genious" (sic).
Re: (Score:1)
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.
Re: (Score:2)
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 signa
Re: (Score:2)
Re: (Score:2)
Sonar from whales you hear 100ds of miles under water, and their singing even farer.
Re: (Score:2)
Or the plane could drop a sonar buoy like they have been doing for more than half a century
So... (Score:2)
I thought this was the purpose of HAARP?? (I kid; nobody actually believed that...)
The first "email": (Score:2)
New sub, who dis?
;)
waves (Score:1)
Either (Score:3)
A whole plane? (Score:2)
MH370 (Score:1)
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.
Re: (Score:2)
There was a lot of good stuff on ppprune.org.
The water was just too deep to capture any sounds from the surface. There were theories that the temperature gradient also redirected sounds horizontally and away from the surface where the detectors were.
Re: (Score:2)
There were theories that the temperature gradient also redirected sounds horizontally and away from the surface where the detectors were.
That is actually a fact, and salt difference gradients have the same (stronger) effect. That is why modern subs (Swedish in particular, but also German and Norwegian) are nearly undetectable in the Baltic seas and close to similar stealthy in the Atlantic.
Limited utility (Score:2)
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
Bad idea (Score:2)
There's a reason subs are sea-gapped.
Unnecessarily Reinventing the Wheel (Score:2)
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.
Subs, yes; flight recorders, no (Score:2)
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.
In a pool, or in the ocean? (Score:2)
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.