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A world of connections - Signal Lake Venture Fund

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A sense <strong>of</strong> things to come<br />

Apr 26th 2007<br />

From The Economist print edition<br />

Sensors can keep a remote eye on<br />

almost anything<br />

THE military uses for wireless technology are<br />

persuasive. For example, pilots can fly above<br />

a war zone and drop thousands <strong>of</strong> small<br />

wireless sensors, the size <strong>of</strong> a small pebble<br />

and costing a dollar apiece, over the terrain.<br />

As soon as they settle the devices start<br />

communicating with each other, weaving<br />

themselves into a dense digital mesh. They<br />

pick up vibration and sound, so they can<br />

identify advancing troops. The sensors can<br />

also detect the presence <strong>of</strong> nuclear, chemical<br />

or biological agents. The information they<br />

pick up is relayed to a satellite. For power,<br />

they “scavenge” energy from the<br />

environment, using solar energy or<br />

temperature changes.<br />

Belle Mellor<br />

The civilian uses are equally impressive.<br />

Forest rangers can drop the sensors from<br />

aeroplanes to detect fires, showing their<br />

exact location and how fast and in what direction they are spreading. Smaller<br />

versions the size <strong>of</strong> grains <strong>of</strong> rice can be used by airlines in the innards <strong>of</strong> aircraft to<br />

check for the presence <strong>of</strong> large insects or rodents that might interfere with the<br />

wiring. Still smaller versions the size <strong>of</strong> specks <strong>of</strong> salt can be added to paint, turning<br />

entire surfaces into wireless sensors that can detect motion or act as smoke alarms<br />

or security systems.<br />

The trouble is that as yet such sensors do not exist. But a lot <strong>of</strong> practical work is<br />

already going into making them a reality. A version <strong>of</strong> the military scenario above,<br />

for instance, was rehearsed in an experiment in March 2001 at an American Marine<br />

Corps base in California. Around a dozen nodes the size <strong>of</strong> a matchbook were<br />

released by a miniature unmanned aircraft. They were able to measure the speed<br />

and direction <strong>of</strong> vehicles from ground vibrations. This proved that the technology,<br />

although still at an early stage, was viable.<br />

The military experiment was supported by America's Defence Advanced Research<br />

Projects Agency (DARPA) and arose from a programme called “smart dust” at the<br />

University <strong>of</strong> California at Berkeley in the 1990s. It created some <strong>of</strong> the technical<br />

foundations needed for sensor networking, such as a pared-down computer<br />

operating system, database and protocol for sensors to send traffic (but “sleep” as<br />

much as possible to prolong battery life). The technologies are open standards, so<br />

may be used freely by other firms, just as the underlying protocol <strong>of</strong> the internet is<br />

open.

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