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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?
Either the sub crew is reciting Beowulf in pig-latin or the prawns are farting.
rewriting history since 2109
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.
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.