A better way to transmit messages underwater

#News(General) [ via IoTForIndiaGroup ]

Tiny acoustic modems will do the job
RADIO waves cannot penetrate water, so cannot be used for submarine communication. That is why the sea is probed by sonar, not radar. But, as people and their machines venture ever farther into the deep, ways of building underwater communications networks would be welcome. And researchers at Newcastle University, in England, led by Jeff Neasham, think they have just the thing to build them with: an acoustic “nanomodem”.

Existing underwater modems, which transmit and receive data via sound, are power-hungry (consuming up to two watts when receiving messages, and as much as 35W when transmitting) and expensive (costing between £5,000 and £15,000, or $7,000-20,000). Dr Neasham’s nanomodems consume only ten milliwatts when listening, and 1W when broadcasting. They cost about £50 a pop. They are also, being about the size of a matchbox, a tenth as big and heavy as the conventional variety. But they suffer from no diminution in range. They are able, as an existing modem is, to broadcast over a distance of up to 2km. That range can, moreover, be extended by deploying a number of them as a network in which each talks to its neighbours, recording messages and passing them on. Existing modems can do this too, in principle. In practice their cost restricts the size of the network.

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