Robotic Fish Track Targets, Communicate With One Another
Roland Piquepaille writes "Many of today's underwater robots need to periodically come up to the surface to communicate with their human supervisors. But researchers at the University of Washington (UW) have developed a new kind of underwater vehicle. The 'Robofish' can work cooperatively with each other. 'The Robofish, which are roughly the size of a 10-pound salmon, look a bit like fish because they use fins rather than propellers.' According to the researchers, such robots 'could cooperatively track moving targets underwater, such as groups of whales or spreading plumes of pollution, or explore caves, underneath ice-covered waters, or in dangerous environments where surfacing might not be possible.' Further information and more pictures are also available for these autonomous fin-actuated underwater vehicles."
Don't worry. PETA will impose a global ban the next time a shark goes tits up while to digest one of these.
They talk about trouble with communications while underwater, but the Skin effect describes how in a conductive media (say, seawater), various frequencies of electromagnetic waves are attenuated with distance. In short, high frequencies travel less distance into the material than lower frequencies. This is why the requirements for shielding of different electronics can be very different -- higher operating frequency implies thinner shielding. And of course it's also why submarines use very low frequencies to communicate. (See also LORAN positioning system.)
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Hey code monkey... learn electronics!